StringUtils (utils4j)

java.lang.Object
- com.varra.util.StringUtils

All Implemented Interfaces:

StringPool
```
@InterfaceAudience.Public
 @InterfaceStability.Evolving
public class StringUtils
extends Object
implements StringPool
```
/**
Operations on String that are null safe.
- IsEmpty/IsBlank - checks if a String contains text
- Trim/Strip - removes leading and trailing whitespace
- Equals - compares two strings null-safe
- startsWith - check if a String starts with a prefix null-safe
- endsWith - check if a String ends with a suffix null-safe
- IndexOf/LastIndexOf/Contains - null-safe index-of checks
- IndexOfAny/LastIndexOfAny/IndexOfAnyBut/LastIndexOfAnyBut - index-of any of a set of Strings
- ContainsOnly/ContainsNone/ContainsAny - does String contains only/none/any of these characters
- Substring/Left/Right/Mid - null-safe substring extractions
- SubstringBefore/SubstringAfter/SubstringBetween - substring extraction relative to other strings
- Split/Join - splits a String into an array of substrings and vice versa
- Remove/Delete - removes part of a String
- Replace/Overlay - Searches a String and replaces one String with another
- Chomp/Chop - removes the last part of a String
- LeftPad/RightPad/Center/Repeat - pads a String
- UpperCase/LowerCase/SwapCase/Capitalize/Uncapitalize - changes the case of a String
- CountMatches - counts the number of occurrences of one String in another
- IsAlpha/IsNumeric/IsWhitespace/IsAsciiPrintable - checks the characters in a String
- DefaultString - protects against a null input String
- Reverse/ReverseDelimited - reverses a String
- Abbreviate - abbreviates a string using ellipsis
- Difference - compares Strings and reports on their differences
- LevensteinDistance - the number of changes needed to change one String into another
The StringUtils class defines certain words related to String handling.
- null - null
- empty - a zero-length string ("")
- space - the space character (' ', char 32)
- whitespace - the characters defined by Character.isWhitespace(char)
- trim - the characters <= 32 as in String.trim()
StringUtils handles null input Strings quietly. That is to say that a null input will return null. Where a boolean or int is being returned details vary by method.

A side effect of the null handling is that a NullPointerException should be considered a bug in StringUtils (except for deprecated methods).

Methods in this class give sample code to explain their operation. The symbol * is used to indicate any input including null.

#ThreadSafe#
Since:

1.0

Version:

$Id: StringUtils.java 1058365 2011-01-13 00:04:49Z niallp $, 1.0

Author:

Apache Software Foundation, Apache Jakarta Turbine, Jon S. Stevens, Daniel L. Rall, Greg Coladonato, Ed Korthof, Rand McNeely, Fredrik Westermarck, Holger Krauth, Alexander Day Chaffee, Henning P. Schmiedehausen, Arun Mammen Thomas, Gary Gregory, Phil Steitz, Al Chou, Michael Davey, Reuben Sivan, Chris Hyzer, Scott Johnson, Rajakrishna V. Reddy

See Also:

String

Field Summary

Fields
Modifier and Type	Field and Description
`static String`	`EMPTY` The empty String `""`.
`static String[]`	`EMPTY_STRING_ARRAY` The Constant EMPTY_STRING_ARRAY.
`static int`	`INDEX_NOT_FOUND` Represents a failed index search.

Fields inherited from interface com.varra.util.StringPool
AMPERSAND, AND, ASTERISK, AT, BACK_SLASH, COLON, COMMA, DASH, DOLLAR, DOLLAR_LEFT_BRACE, DOT, DOT_CLASS, DOT_JAVA, DOTDOT, EMPTY_ARRAY, EQUALS, EXCLAMATION_MARK, FALSE, HASH, HAT, ISO_8859_1, LEFT_BRACE, LEFT_BRACKET, LEFT_CHEV, LEFT_SQ_BRACKET, N, NEWLINE, NO, NULL, OFF, ON, ONE, PERCENT, PIPE, PLUS, QUESTION_MARK, QUOTE, RETURN, RIGHT_BRACE, RIGHT_BRACKET, RIGHT_CHEV, RIGHT_SQ_BRACKET, SEMICOLON, SINGLE_QUOTE, SLASH, SPACE, STAR, TAB, TRUE, UNDERSCORE, UTF_8, Y, YES, ZERO

Constructor Summary

Constructors
Constructor and Description

StringUtils()
StringUtils instances should NOT be constructed in standard programming.

Constructors
Constructor and Description
`StringUtils()` `StringUtils` instances should NOT be constructed in standard programming.

Method Summary

All Methods Static Methods Concrete Methods Deprecated Methods
Modifier and Type	Method and Description
`static String`	`abbreviate(String str, int maxWidth)` Abbreviates a String using ellipses.
`static String`	`abbreviate(String str, int offset, int maxWidth)` Abbreviates a String using ellipses.
`static String`	`abbreviateMiddle(String str, String middle, int length)` Abbreviates a String to the length passed, replacing the middle characters with the supplied replacement String.
`static String`	`capitalise(String str)` Deprecated. Use the standardly named `capitalize(String)`. Method will be removed in Commons Lang 3.0.
`static String`	`capitaliseAllWords(String str)` Deprecated. Use the relocated `capitalize(String)`. Method will be removed in Commons Lang 3.0.
`static String`	`capitalize(String str)` Capitalizes a String changing the first letter to title case as per `Character.toTitleCase(char)`.
`static String`	`capitalize(String str, char[] delimiters)` Capitalizes all the delimiter separated words in a String.
`static String`	`center(String str, int size)` Centers a String in a larger String of size `size` using the space character (' ').
`static String`	`center(String str, int size, char padChar)` Centers a String in a larger String of size `size`.
`static String`	`center(String str, int size, String padStr)` Centers a String in a larger String of size `size`.
`static String`	`chomp(String str)` Removes one newline from end of a String if it's there, otherwise leave it alone.
`static String`	`chomp(String str, String separator)` Removes `separator` from the end of `str` if it's there, otherwise leave it alone.
`static String`	`chompLast(String str)` Deprecated. Use `chomp(String)` instead. Method will be removed in Commons Lang 3.0.
`static String`	`chompLast(String str, String sep)` Deprecated. Use `chomp(String,String)` instead. Method will be removed in Commons Lang 3.0.
`static String`	`chop(String str)` Remove the last character from a String.
`static String`	`chopNewline(String str)` Deprecated. Use `chomp(String)` instead. Method will be removed in Commons Lang 3.0.
`static String`	`clean(String str)` Deprecated. Use the clearer named `trimToEmpty(String)`. Method will be removed in Commons Lang 3.0.
`static String`	`concatenate(Object[] array)` Deprecated. Use the better named `join(Object[])` instead. Method will be removed in Commons Lang 3.0.
`static boolean`	`contains(String str, char searchChar)` Checks if String contains a search character, handling `null`.
`static boolean`	`contains(String str, String searchStr)` Checks if String contains a search String, handling `null`.
`static boolean`	`containsAny(String str, char[] searchChars)` Checks if the String contains any character in the given set of characters.
`static boolean`	`containsAny(String str, String searchChars)` Checks if the String contains any character in the given set of characters.
`static boolean`	`containsIgnoreCase(String str, String searchStr)` Checks if String contains a search String irrespective of case, handling `null`.
`static boolean`	`containsNone(String str, char[] searchChars)` Checks that the String does not contain certain characters.
`static boolean`	`containsNone(String str, String invalidChars)` Checks that the String does not contain certain characters.
`static boolean`	`containsOnly(String str, char[] valid)` Checks if the String contains only certain characters.
`static boolean`	`containsOnly(String str, String validChars)` Checks if the String contains only certain characters.
`static int`	`countMatches(String str, String sub)` Counts how many times the substring appears in the larger String.
`static String`	`defaultIfBlank(String str, String defaultStr)` Returns either the passed in String, or if the String is whitespace, empty ("") or `null`, the value of `defaultStr`.
`static String`	`defaultIfEmpty(String str, String defaultStr)` Returns either the passed in String, or if the String is empty or `null`, the value of `defaultStr`.
`static String`	`defaultString(String str)` Returns either the passed in String, or if the String is `null`, an empty String ("").
`static String`	`defaultString(String str, String defaultStr)` Returns either the passed in String, or if the String is `null`, the value of `defaultStr`.
`static String`	`deleteWhitespace(String str)` Deletes all whitespaces from a String as defined by `Character.isWhitespace(char)`.
`static String`	`difference(String str1, String str2)` Compares two Strings, and returns the portion where they differ.
`static boolean`	`endsWith(String str, String suffix)` Check if a String ends with a specified suffix.
`static boolean`	`endsWithAny(String string, String[] searchStrings)` Check if a String ends with any of an array of specified strings.
`static boolean`	`endsWithIgnoreCase(String str, String suffix)` Case insensitive check if a String ends with a specified suffix.
`static boolean`	`equals(String str1, String str2)` Compares two Strings, returning `true` if they are equal.
`static boolean`	`equalsIgnoreCase(String str1, String str2)` Compares two Strings, returning `true` if they are equal ignoring the case.
`static boolean`	`equalsOfAny(String primary, String... strings)` Compares the given string against the list of Strings, returning `true` if they contain this string.
`static boolean`	`equalsOfAnyIgnoreCase(String primary, String... strings)` Compares the given string against the list of Strings, returning `true` if they contain this string.
`static String`	`getChomp(String str, String sep)` Deprecated. Use `substringAfterLast(String, String)` instead (although this doesn't include the separator) Method will be removed in Commons Lang 3.0.
`static String`	`getCommonPrefix(String[] strs)` Compares all Strings in an array and returns the initial sequence of characters that is common to all of them.
`static int`	`getLevenshteinDistance(String s, String t)` Find the Levenshtein distance between two Strings.
`static String`	`getNestedString(String str, String tag)` Deprecated. Use the better named `substringBetween(String, String)`. Method will be removed in Commons Lang 3.0.
`static String`	`getNestedString(String str, String open, String close)` Deprecated. Use the better named `substringBetween(String, String, String)`. Method will be removed in Commons Lang 3.0.
`static String`	`getPrechomp(String str, String sep)` Deprecated. Use `substringBefore(String,String)` instead (although this doesn't include the separator). Method will be removed in Commons Lang 3.0.
`static int`	`indexOf(String str, char searchChar)` Finds the first index within a String, handling `null`.
`static int`	`indexOf(String str, char searchChar, int startPos)` Finds the first index within a String from a start position, handling `null`.
`static int`	`indexOf(String str, String searchStr)` Finds the first index within a String, handling `null`.
`static int`	`indexOf(String str, String searchStr, int startPos)` Finds the first index within a String, handling `null`.
`static int`	`indexOfAny(String str, char[] searchChars)` Search a String to find the first index of any character in the given set of characters.
`static int`	`indexOfAny(String str, String searchChars)` Search a String to find the first index of any character in the given set of characters.
`static int`	`indexOfAny(String str, String[] searchStrs)` Find the first index of any of a set of potential substrings.
`static int`	`indexOfAnyBut(String str, char[] searchChars)` Search a String to find the first index of any character not in the given set of characters.
`static int`	`indexOfAnyBut(String str, String searchChars)` Search a String to find the first index of any character not in the given set of characters.
`static int`	`indexOfDifference(String[] strs)` Compares all Strings in an array and returns the index at which the Strings begin to differ.
`static int`	`indexOfDifference(String str1, String str2)` Compares two Strings, and returns the index at which the Strings begin to differ.
`static int`	`indexOfIgnoreCase(String str, String searchStr)` Case in-sensitive find of the first index within a String.
`static int`	`indexOfIgnoreCase(String str, String searchStr, int startPos)` Case in-sensitive find of the first index within a String from the specified position.
`static boolean`	`isAllLowerCase(String str)` Checks if the String contains only lowercase characters.
`static boolean`	`isAllUpperCase(String str)` Checks if the String contains only uppercase characters.
`static boolean`	`isAlpha(String str)` Checks if the String contains only unicode letters.
`static boolean`	`isAlphanumeric(String str)` Checks if the String contains only unicode letters or digits.
`static boolean`	`isAlphanumericSpace(String str)` Checks if the String contains only unicode letters, digits or space ( `' '`).
`static boolean`	`isAlphaSpace(String str)` Checks if the String contains only unicode letters and space (' ').
`static boolean`	`isAsciiPrintable(char ch)` Checks whether the character is ASCII 7 bit printable.
`static boolean`	`isAsciiPrintable(String str)` Checks if the string contains only ASCII printable characters.
`static boolean`	`isBlank(String str)` Checks if a String is whitespace, empty ("") or null.
`static boolean`	`isEmpty(boolean[] array)` Checks if an array of primitive booleans is empty or `null`.
`static boolean`	`isEmpty(byte[] array)` Checks if an array of primitive bytes is empty or `null`.
`static boolean`	`isEmpty(char[] array)` Checks if an array of primitive chars is empty or `null`.
`static boolean`	`isEmpty(double[] array)` Checks if an array of primitive doubles is empty or `null`.
`static boolean`	`isEmpty(float[] array)` Checks if an array of primitive floats is empty or `null`.
`static boolean`	`isEmpty(int[] array)` Checks if an array of primitive ints is empty or `null`.
`static boolean`	`isEmpty(long[] array)` Checks if an array of primitive longs is empty or `null`.
`static boolean`	`isEmpty(Object[] array)` Checks if an array of Objects is empty or `null`.
`static boolean`	`isEmpty(short[] array)` Checks if an array of primitive shorts is empty or `null`.
`static boolean`	`isEmpty(String str)` Checks if a String is empty ("") or null.
`static boolean`	`isHighSurrogate(char ch)` Indicates whether `ch` is a high- (or leading-) surrogate code unit that is used for representing supplementary characters in UTF-16 encoding.
`static boolean`	`isNotBlank(String str)` Checks if a String is not empty (""), not null and not whitespace only.
`static boolean`	`isNotEmpty(boolean[] array)` Checks if an array of primitive booleans is not empty or not `null`.
`static boolean`	`isNotEmpty(byte[] array)` Checks if an array of primitive bytes is not empty or not `null`.
`static boolean`	`isNotEmpty(char[] array)` Checks if an array of primitive chars is not empty or not `null`.
`static boolean`	`isNotEmpty(double[] array)` Checks if an array of primitive doubles is not empty or not `null`.
`static boolean`	`isNotEmpty(float[] array)` Checks if an array of primitive floats is not empty or not `null`.
`static boolean`	`isNotEmpty(int[] array)` Checks if an array of primitive ints is not empty or not `null`.
`static boolean`	`isNotEmpty(long[] array)` Checks if an array of primitive longs is not empty or not `null`.
`static boolean`	`isNotEmpty(Object[] array)` Checks if an array of Objects is not empty or not `null`.
`static boolean`	`isNotEmpty(short[] array)` Checks if an array of primitive shorts is not empty or not `null`.
`static boolean`	`isNotEmpty(String str)` Checks if a String is not empty ("") and not null.
`static boolean`	`isNumeric(String str)` Checks if the String contains only unicode digits.
`static boolean`	`isNumericSpace(String str)` Checks if the String contains only unicode digits or space ( `' '`).
`static boolean`	`isWhitespace(String str)` Checks if the String contains only whitespace.
`static String`	`join(Collection<?> collection, char separator)` Joins the elements of the provided `Collection` into a single String containing the provided elements.
`static String`	`join(Collection<?> collection, String separator)` Joins the elements of the provided `Collection` into a single String containing the provided elements.
`static String`	`join(Iterator<?> iterator, char separator)` Joins the elements of the provided `Iterator` into a single String containing the provided elements.
`static String`	`join(Iterator<?> iterator, String separator)` Joins the elements of the provided `Iterator` into a single String containing the provided elements.
`static String`	`join(Object[] array)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static String`	`join(Object[] array, char separator)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static String`	`join(Object[] array, char separator, int startIndex, int endIndex)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static String`	`join(Object[] array, String separator)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static String`	`join(Object[] array, String separator, int startIndex, int endIndex)` Joins the elements of the provided array into a single String containing the provided list of elements.
`static int`	`lastIndexOf(String str, char searchChar)` Finds the last index within a String, handling `null`.
`static int`	`lastIndexOf(String str, char searchChar, int startPos)` Finds the last index within a String from a start position, handling `null`.
`static int`	`lastIndexOf(String str, String searchStr)` Finds the last index within a String, handling `null`.
`static int`	`lastIndexOf(String str, String searchStr, int startPos)` Finds the first index within a String, handling `null`.
`static int`	`lastIndexOfAny(String str, String[] searchStrs)` Find the latest index of any of a set of potential substrings.
`static int`	`lastIndexOfIgnoreCase(String str, String searchStr)` Case in-sensitive find of the last index within a String.
`static int`	`lastIndexOfIgnoreCase(String str, String searchStr, int startPos)` Case in-sensitive find of the last index within a String from the specified position.
`static int`	`lastOrdinalIndexOf(String str, String searchStr, int ordinal)` Finds the n-th last index within a String, handling `null`.
`static String`	`left(String str, int len)` Gets the leftmost `len` characters of a String.
`static String`	`leftPad(String str, int size)` Left pad a String with spaces (' ').
`static String`	`leftPad(String str, int size, char padChar)` Left pad a String with a specified character.
`static String`	`leftPad(String str, int size, String padStr)` Left pad a String with a specified String.
`static int`	`length(String str)` Gets a String's length or `0` if the String is `null`.
`static String`	`lowerCase(String str)` Converts a String to lower case as per `String.toLowerCase()`.
`static String`	`lowerCase(String str, Locale locale)` Converts a String to lower case as per `String.toLowerCase(Locale)` .
`static String`	`mid(String str, int pos, int len)` Gets `len` characters from the middle of a String.
`static String`	`normalizeSpace(String str)` Similar to http:// www.w3.org/TR/xpath/#function-normalize -space
`static int`	`ordinalIndexOf(String str, String searchStr, int ordinal)` Finds the n-th index within a String, handling `null`.
`static String`	`overlay(String str, String overlay, int start, int end)` Overlays part of a String with another String.
`static String`	`overlayString(String text, String overlay, int start, int end)` Deprecated. Use better named `overlay(String, String, int, int)` instead. Method will be removed in Commons Lang 3.0.
`static String`	`pluralize(String word)` Pluralize.
`static String`	`prechomp(String str, String sep)` Deprecated. Use `substringAfter(String,String)` instead. Method will be removed in Commons Lang 3.0.
`static String`	`remove(String str, char remove)` Removes all occurrences of a character from within the source string.
`static String`	`remove(String str, String remove)` Removes all occurrences of a substring from within the source string.
`static String`	`removeEnd(String str, String remove)` Removes a substring only if it is at the end of a source string, otherwise returns the source string.
`static String`	`removeEndIgnoreCase(String str, String remove)` Case insensitive removal of a substring if it is at the end of a source string, otherwise returns the source string.
`static String`	`removeStart(String str, String remove)` Removes a substring only if it is at the begining of a source string, otherwise returns the source string.
`static String`	`removeStartIgnoreCase(String str, String remove)` Case insensitive removal of a substring if it is at the begining of a source string, otherwise returns the source string.
`static String`	`repeat(String str, int repeat)` Repeat a String `repeat` times to form a new String.
`static String`	`repeat(String str, String separator, int repeat)` Repeat a String `repeat` times to form a new String, with a String separator injected each time.
`static String`	`replace(String text, String searchString, String replacement)` Replaces all occurrences of a String within another String.
`static String`	`replace(String text, String searchString, String replacement, int max)` Replaces a String with another String inside a larger String, for the first `max` values of the search String.
`static String`	`replaceChars(String str, char searchChar, char replaceChar)` Replaces all occurrences of a character in a String with another.
`static String`	`replaceChars(String str, String searchChars, String replaceChars)` Replaces multiple characters in a String in one go.
`static String`	`replaceEach(String text, String[] searchList, String[] replacementList)` Replaces all occurrences of Strings within another String.
`static String`	`replaceEachRepeatedly(String text, String[] searchList, String[] replacementList)` Replaces all occurrences of Strings within another String.
`static String`	`replaceOnce(String text, String searchString, String replacement)` Replaces a String with another String inside a larger String, once.
`static void`	`reverse(Object[] array)` Reverses the order of the given array.
`static String`	`reverse(String str)` Reverses a String as per `StringBuilder.reverse()`.
`static String`	`reverseDelimited(String str, char separatorChar)` Reverses a String that is delimited by a specific character.
`static String`	`reverseDelimitedString(String str, String separatorChars)` Deprecated. Use `reverseDelimited(String, char)` instead. This method is broken as the join doesn't know which char to use. Method will be removed in Commons Lang 3.0.
`static String`	`right(String str, int len)` Gets the rightmost `len` characters of a String.
`static String`	`rightPad(String str, int size)` Right pad a String with spaces (' ').
`static String`	`rightPad(String str, int size, char padChar)` Right pad a String with a specified character.
`static String`	`rightPad(String str, int size, String padStr)` Right pad a String with a specified String.
`static String[]`	`split(String str)` Splits the provided text into an array, using whitespace as the separator.
`static String[]`	`split(String str, char separatorChar)` Splits the provided text into an array, separator specified.
`static String[]`	`split(String str, String separatorChars)` Splits the provided text into an array, separators specified.
`static String[]`	`split(String str, String separatorChars, int max)` Splits the provided text into an array with a maximum length, separators specified.
`static String[]`	`splitByCharacterType(String str)` Splits a String by Character type as returned by `java.lang.Character.getType(char)`.
`static String[]`	`splitByCharacterTypeCamelCase(String str)` Splits a String by Character type as returned by `java.lang.Character.getType(char)`.
`static String[]`	`splitByWholeSeparator(String str, String separator)` Splits the provided text into an array, separator string specified.
`static String[]`	`splitByWholeSeparator(String str, String separator, int max)` Splits the provided text into an array, separator string specified.
`static String[]`	`splitByWholeSeparatorPreserveAllTokens(String str, String separator)` Splits the provided text into an array, separator string specified.
`static String[]`	`splitByWholeSeparatorPreserveAllTokens(String str, String separator, int max)` Splits the provided text into an array, separator string specified.
`static String[]`	`splitPreserveAllTokens(String str)` Splits the provided text into an array, using whitespace as the separator, preserving all tokens, including empty tokens created by adjacent separators.
`static String[]`	`splitPreserveAllTokens(String str, char separatorChar)` Splits the provided text into an array, separator specified, preserving all tokens, including empty tokens created by adjacent separators.
`static String[]`	`splitPreserveAllTokens(String str, String separatorChars)` Splits the provided text into an array, separators specified, preserving all tokens, including empty tokens created by adjacent separators.
`static String[]`	`splitPreserveAllTokens(String str, String separatorChars, int max)` Splits the provided text into an array with a maximum length, separators specified, preserving all tokens, including empty tokens created by adjacent separators.
`static boolean`	`startsWith(String str, String prefix)` Check if a String starts with a specified prefix.
`static boolean`	`startsWithAny(String string, String[] searchStrings)` Check if a String starts with any of an array of specified strings.
`static boolean`	`startsWithIgnoreCase(String str, String prefix)` Case insensitive check if a String starts with a specified prefix.
`static String`	`strip(String str)` Strips whitespace from the start and end of a String.
`static String`	`strip(String str, String stripChars)` Strips any of a set of characters from the start and end of a String.
`static String[]`	`stripAll(String[] strs)` Strips whitespace from the start and end of every String in an array.
`static String[]`	`stripAll(String[] strs, String stripChars)` Strips any of a set of characters from the start and end of every String in an array.
`static String`	`stripEnd(String str, String stripChars)` Strips any of a set of characters from the end of a String.
`static String`	`stripStart(String str, String stripChars)` Strips any of a set of characters from the start of a String.
`static String`	`stripToEmpty(String str)` Strips whitespace from the start and end of a String returning an empty String if `null` input.
`static String`	`stripToNull(String str)` Strips whitespace from the start and end of a String returning `null` if the String is empty ("") after the strip.
`static String`	`substring(String str, int start)` Gets a substring from the specified String avoiding exceptions.
`static String`	`substring(String str, int start, int end)` Gets a substring from the specified String avoiding exceptions.
`static String`	`substringAfter(String str, String separator)` Gets the substring after the first occurrence of a separator.
`static String`	`substringAfterLast(String str, String separator)` Gets the substring after the last occurrence of a separator.
`static String`	`substringBefore(String str, String separator)` Gets the substring before the first occurrence of a separator.
`static String`	`substringBeforeLast(String str, String separator)` Gets the substring before the last occurrence of a separator.
`static String`	`substringBetween(String str, String tag)` Gets the String that is nested in between two instances of the same String.
`static String`	`substringBetween(String str, String open, String close)` Gets the String that is nested in between two Strings.
`static String[]`	`substringsBetween(String str, String open, String close)` Searches a String for substrings delimited by a start and end tag, returning all matching substrings in an array.
`static String`	`swapCase(String str)` Swaps the case of a String changing upper and title case to lower case, and lower case to upper case.
`static String`	`toString(Object obj)` Gets the `toString` of an `Object` returning an empty string ("") if `null` input.
`static String`	`trim(String str)` Removes control characters (char <= 32) from both ends of this String, handling `null` by returning `null`.
`static String`	`trimToEmpty(String str)` Removes control characters (char <= 32) from both ends of this String returning an empty String ("") if the String is empty ("") after the trim or if it is `null`.
`static String`	`trimToNull(String str)` Removes control characters (char <= 32) from both ends of this String returning `null` if the String is empty ("") after the trim or if it is `null`.
`static String`	`uncapitalise(String str)` Deprecated. Use the standardly named `uncapitalize(String)`. Method will be removed in Commons Lang 3.0.
`static String`	`uncapitalize(String str)` Uncapitalizes a String changing the first letter to title case as per `Character.toLowerCase(char)`.
`static String`	`upperCase(String str)` Converts a String to upper case as per `String.toUpperCase()`.
`static String`	`upperCase(String str, Locale locale)` Converts a String to upper case as per `String.toUpperCase(Locale)` .

Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail
- EMPTY_STRING_ARRAY
```
public static final String[] EMPTY_STRING_ARRAY
```
  The Constant EMPTY_STRING_ARRAY.
- EMPTY
```
public static final String EMPTY
```
  The empty String "".
  
  Since:
  
  2.0
  
  See Also:
  
  Constant Field Values
- INDEX_NOT_FOUND
```
public static final int INDEX_NOT_FOUND
```
  Represents a failed index search.
  
  Since:
  
  2.1
  
  See Also:
  
  Constant Field Values

Constructor Detail
- StringUtils
```
public StringUtils()
```
  StringUtils instances should NOT be constructed in standard programming. Instead, the class should be used as StringUtils.trim(" foo ");.
  
  This constructor is public to permit tools that require a JavaBean instance to operate.

Method Detail

isEmpty
```
public static boolean isEmpty(Object[] array)
```
Checks if an array of Objects is empty or null.

Parameters:

array - the array to test

Returns:

true if the array is empty or null

Since:

2.1

isEmpty
```
public static boolean isEmpty(long[] array)
```
Checks if an array of primitive longs is empty or null.

Parameters:

array - the array to test

Returns:

true if the array is empty or null

Since:

2.1

isEmpty
```
public static boolean isEmpty(int[] array)
```
Checks if an array of primitive ints is empty or null.

Parameters:

array - the array to test

Returns:

true if the array is empty or null

Since:

2.1

isEmpty
```
public static boolean isEmpty(short[] array)
```
Checks if an array of primitive shorts is empty or null.

Parameters:

array - the array to test

Returns:

true if the array is empty or null

Since:

2.1

isEmpty
```
public static boolean isEmpty(char[] array)
```
Checks if an array of primitive chars is empty or null.

Parameters:

array - the array to test

Returns:

true if the array is empty or null

Since:

2.1

isEmpty
```
public static boolean isEmpty(byte[] array)
```
Checks if an array of primitive bytes is empty or null.

Parameters:

array - the array to test

Returns:

true if the array is empty or null

Since:

2.1

isEmpty
```
public static boolean isEmpty(double[] array)
```
Checks if an array of primitive doubles is empty or null.

Parameters:

array - the array to test

Returns:

true if the array is empty or null

Since:

2.1

isEmpty
```
public static boolean isEmpty(float[] array)
```
Checks if an array of primitive floats is empty or null.

Parameters:

array - the array to test

Returns:

true if the array is empty or null

Since:

2.1

isEmpty
```
public static boolean isEmpty(boolean[] array)
```
Checks if an array of primitive booleans is empty or null.

Parameters:

array - the array to test

Returns:

true if the array is empty or null

Since:

2.1

isNotEmpty
```
public static boolean isNotEmpty(Object[] array)
```
Checks if an array of Objects is not empty or not null.

Parameters:

array - the array to test

Returns:

true if the array is not empty or not null

Since:

2.5

isNotEmpty
```
public static boolean isNotEmpty(long[] array)
```
Checks if an array of primitive longs is not empty or not null.

Parameters:

array - the array to test

Returns:

true if the array is not empty or not null

Since:

2.5

isNotEmpty
```
public static boolean isNotEmpty(int[] array)
```
Checks if an array of primitive ints is not empty or not null.

Parameters:

array - the array to test

Returns:

true if the array is not empty or not null

Since:

2.5

isNotEmpty
```
public static boolean isNotEmpty(short[] array)
```
Checks if an array of primitive shorts is not empty or not null.

Parameters:

array - the array to test

Returns:

true if the array is not empty or not null

Since:

2.5

isNotEmpty
```
public static boolean isNotEmpty(char[] array)
```
Checks if an array of primitive chars is not empty or not null.

Parameters:

array - the array to test

Returns:

true if the array is not empty or not null

Since:

2.5

isNotEmpty
```
public static boolean isNotEmpty(byte[] array)
```
Checks if an array of primitive bytes is not empty or not null.

Parameters:

array - the array to test

Returns:

true if the array is not empty or not null

Since:

2.5

isNotEmpty
```
public static boolean isNotEmpty(double[] array)
```
Checks if an array of primitive doubles is not empty or not null.

Parameters:

array - the array to test

Returns:

true if the array is not empty or not null

Since:

2.5

isNotEmpty
```
public static boolean isNotEmpty(float[] array)
```
Checks if an array of primitive floats is not empty or not null.

Parameters:

array - the array to test

Returns:

true if the array is not empty or not null

Since:

2.5

isNotEmpty
```
public static boolean isNotEmpty(boolean[] array)
```
Checks if an array of primitive booleans is not empty or not null.

Parameters:

array - the array to test

Returns:

true if the array is not empty or not null

Since:

2.5

isEmpty
```
public static boolean isEmpty(String str)
```
Checks if a String is empty ("") or null.
```
 StringUtils.isEmpty(null)      = true
 StringUtils.isEmpty("")        = true
 StringUtils.isEmpty(" ")       = false
 StringUtils.isEmpty("bob")     = false
 StringUtils.isEmpty("  bob  ") = false
 
```
NOTE: This method changed in Lang version 2.0. It no longer trims the String. That functionality is available in isBlank().
Parameters:

str - the String to check, may be null

Returns:

true if the String is empty or null

isNotEmpty

public static boolean isNotEmpty(String str)

Checks if a String is not empty ("") and not null.

 StringUtils.isNotEmpty(null)      = false
 StringUtils.isNotEmpty("")        = false
 StringUtils.isNotEmpty(" ")       = true
 StringUtils.isNotEmpty("bob")     = true
 StringUtils.isNotEmpty("  bob  ") = true

Parameters:: str - the String to check, may be null
Returns:: true if the String is not empty and not null

isBlank

public static boolean isBlank(String str)

Checks if a String is whitespace, empty ("") or null.

 StringUtils.isBlank(null)      = true
 StringUtils.isBlank("")        = true
 StringUtils.isBlank(" ")       = true
 StringUtils.isBlank("bob")     = false
 StringUtils.isBlank("  bob  ") = false

Parameters:: str - the String to check, may be null
Returns:: true if the String is null, empty or whitespace
Since:: 2.0

isNotBlank

public static boolean isNotBlank(String str)

Checks if a String is not empty (""), not null and not whitespace only.

 StringUtils.isNotBlank(null)      = false
 StringUtils.isNotBlank("")        = false
 StringUtils.isNotBlank(" ")       = false
 StringUtils.isNotBlank("bob")     = true
 StringUtils.isNotBlank("  bob  ") = true

Parameters:: str - the String to check, may be null
Returns:: true if the String is not empty and not null and not whitespace
Since:: 2.0

clean
```
public static String clean(String str)
```
Deprecated. Use the clearer named trimToEmpty(String). Method will be removed in Commons Lang 3.0.
Removes control characters (char <= 32) from both ends of this String, handling null by returning an empty String ("").
```
 StringUtils.clean(null)          = ""
 StringUtils.clean("")            = ""
 StringUtils.clean("abc")         = "abc"
 StringUtils.clean("    abc    ") = "abc"
 StringUtils.clean("     ")       = ""
 
```
Parameters:

str - the String to clean, may be null

Returns:

the trimmed text, never null

See Also:

String.trim()

trim
```
public static String trim(String str)
```
Removes control characters (char <= 32) from both ends of this String, handling null by returning null.

The String is trimmed using String.trim(). Trim removes start and end characters <= 32. To strip whitespace use strip(String).

To trim your choice of characters, use the strip(String, String) methods.
```
 StringUtils.trim(null)          = null
 StringUtils.trim("")            = ""
 StringUtils.trim("     ")       = ""
 StringUtils.trim("abc")         = "abc"
 StringUtils.trim("    abc    ") = "abc"
 
```
Parameters:

str - the String to be trimmed, may be null

Returns:

the trimmed string, null if null String input

trimToNull
```
public static String trimToNull(String str)
```
Removes control characters (char <= 32) from both ends of this String returning null if the String is empty ("") after the trim or if it is null.
The String is trimmed using String.trim(). Trim removes start and end characters <= 32. To strip whitespace use stripToNull(String).
```
 StringUtils.trimToNull(null)          = null
 StringUtils.trimToNull("")            = null
 StringUtils.trimToNull("     ")       = null
 StringUtils.trimToNull("abc")         = "abc"
 StringUtils.trimToNull("    abc    ") = "abc"
 
```
Parameters:

str - the String to be trimmed, may be null

Returns:

the trimmed String, null if only chars <= 32, empty or null String input

Since:

2.0

trimToEmpty
```
public static String trimToEmpty(String str)
```
Removes control characters (char <= 32) from both ends of this String returning an empty String ("") if the String is empty ("") after the trim or if it is null.
The String is trimmed using String.trim(). Trim removes start and end characters <= 32. To strip whitespace use stripToEmpty(String).
```
 StringUtils.trimToEmpty(null)          = ""
 StringUtils.trimToEmpty("")            = ""
 StringUtils.trimToEmpty("     ")       = ""
 StringUtils.trimToEmpty("abc")         = "abc"
 StringUtils.trimToEmpty("    abc    ") = "abc"
 
```
Parameters:

str - the String to be trimmed, may be null

Returns:

the trimmed String, or an empty String if null input

Since:

2.0

strip

public static String strip(String str)

Strips whitespace from the start and end of a String.

This is similar to trim(String) but removes whitespace. Whitespace is defined by Character.isWhitespace(char).

A null input String returns null.

 StringUtils.strip(null)     = null
 StringUtils.strip("")       = ""
 StringUtils.strip("   ")    = ""
 StringUtils.strip("abc")    = "abc"
 StringUtils.strip("  abc")  = "abc"
 StringUtils.strip("abc  ")  = "abc"
 StringUtils.strip(" abc ")  = "abc"
 StringUtils.strip(" ab c ") = "ab c"

Parameters:: str - the String to remove whitespace from, may be null
Returns:: the stripped String, null if null String input

stripToNull

public static String stripToNull(String str)

Strips whitespace from the start and end of a String returning null if the String is empty ("") after the strip.

This is similar to trimToNull(String) but removes whitespace. Whitespace is defined by Character.isWhitespace(char).

 StringUtils.stripToNull(null)     = null
 StringUtils.stripToNull("")       = null
 StringUtils.stripToNull("   ")    = null
 StringUtils.stripToNull("abc")    = "abc"
 StringUtils.stripToNull("  abc")  = "abc"
 StringUtils.stripToNull("abc  ")  = "abc"
 StringUtils.stripToNull(" abc ")  = "abc"
 StringUtils.stripToNull(" ab c ") = "ab c"

Parameters:: str - the String to be stripped, may be null
Returns:: the stripped String, null if whitespace, empty or null String input
Since:: 2.0

stripToEmpty

public static String stripToEmpty(String str)

Strips whitespace from the start and end of a String returning an empty String if null input.

This is similar to trimToEmpty(String) but removes whitespace. Whitespace is defined by Character.isWhitespace(char).

 StringUtils.stripToEmpty(null)     = ""
 StringUtils.stripToEmpty("")       = ""
 StringUtils.stripToEmpty("   ")    = ""
 StringUtils.stripToEmpty("abc")    = "abc"
 StringUtils.stripToEmpty("  abc")  = "abc"
 StringUtils.stripToEmpty("abc  ")  = "abc"
 StringUtils.stripToEmpty(" abc ")  = "abc"
 StringUtils.stripToEmpty(" ab c ") = "ab c"

Parameters:: str - the String to be stripped, may be null
Returns:: the trimmed String, or an empty String if null input
Since:: 2.0

strip
```
public static String strip(String str,
                           String stripChars)
```
Strips any of a set of characters from the start and end of a String. This is similar to String.trim() but allows the characters to be stripped to be controlled.

A null input String returns null. An empty string ("") input returns the empty string.

If the stripChars String is null, whitespace is stripped as defined by Character.isWhitespace(char). Alternatively use strip(String).
```
 StringUtils.strip(null, *)          = null
 StringUtils.strip("", *)            = ""
 StringUtils.strip("abc", null)      = "abc"
 StringUtils.strip("  abc", null)    = "abc"
 StringUtils.strip("abc  ", null)    = "abc"
 StringUtils.strip(" abc ", null)    = "abc"
 StringUtils.strip("  abcyx", "xyz") = "  abc"
 
```
Parameters:

str - the String to remove characters from, may be null

stripChars - the characters to remove, null treated as whitespace

Returns:

the stripped String, null if null String input

stripStart

public static String stripStart(String str,
                                String stripChars)

Strips any of a set of characters from the start of a String.

A null input String returns null. An empty string ("") input returns the empty string.

If the stripChars String is null, whitespace is stripped as defined by Character.isWhitespace(char).

 StringUtils.stripStart(null, *)          = null
 StringUtils.stripStart("", *)            = ""
 StringUtils.stripStart("abc", "")        = "abc"
 StringUtils.stripStart("abc", null)      = "abc"
 StringUtils.stripStart("  abc", null)    = "abc"
 StringUtils.stripStart("abc  ", null)    = "abc  "
 StringUtils.stripStart(" abc ", null)    = "abc "
 StringUtils.stripStart("yxabc  ", "xyz") = "abc  "

Parameters:: str - the String to remove characters from, may be null; stripChars - the characters to remove, null treated as whitespace
Returns:: the stripped String, null if null String input

stripEnd

public static String stripEnd(String str,
                              String stripChars)

Strips any of a set of characters from the end of a String.

A null input String returns null. An empty string ("") input returns the empty string.

If the stripChars String is null, whitespace is stripped as defined by Character.isWhitespace(char).

 StringUtils.stripEnd(null, *)          = null
 StringUtils.stripEnd("", *)            = ""
 StringUtils.stripEnd("abc", "")        = "abc"
 StringUtils.stripEnd("abc", null)      = "abc"
 StringUtils.stripEnd("  abc", null)    = "  abc"
 StringUtils.stripEnd("abc  ", null)    = "abc"
 StringUtils.stripEnd(" abc ", null)    = " abc"
 StringUtils.stripEnd("  abcyx", "xyz") = "  abc"
 StringUtils.stripEnd("120.00", ".0")   = "12"

Parameters:: str - the String to remove characters from, may be null; stripChars - the set of characters to remove, null treated as whitespace
Returns:: the stripped String, null if null String input

stripAll
```
public static String[] stripAll(String[] strs)
```
Strips whitespace from the start and end of every String in an array. Whitespace is defined by Character.isWhitespace(char).

A new array is returned each time, except for length zero. A null array will return null. An empty array will return itself. A null array entry will be ignored.
```
 StringUtils.stripAll(null)             = null
 StringUtils.stripAll([])               = []
 StringUtils.stripAll(["abc", "  abc"]) = ["abc", "abc"]
 StringUtils.stripAll(["abc  ", null])  = ["abc", null]
 
```
Parameters:

strs - the array to remove whitespace from, may be null

Returns:

the stripped Strings, null if null array input

stripAll
```
public static String[] stripAll(String[] strs,
                                String stripChars)
```
Strips any of a set of characters from the start and end of every String in an array.
Whitespace is defined by Character.isWhitespace(char).

A new array is returned each time, except for length zero. A null array will return null. An empty array will return itself. A null array entry will be ignored. A null stripChars will strip whitespace as defined by Character.isWhitespace(char).
```
 StringUtils.stripAll(null, *)                = null
 StringUtils.stripAll([], *)                  = []
 StringUtils.stripAll(["abc", "  abc"], null) = ["abc", "abc"]
 StringUtils.stripAll(["abc  ", null], null)  = ["abc", null]
 StringUtils.stripAll(["abc  ", null], "yz")  = ["abc  ", null]
 StringUtils.stripAll(["yabcz", null], "yz")  = ["abc", null]
 
```
Parameters:

strs - the array to remove characters from, may be null

stripChars - the characters to remove, null treated as whitespace

Returns:

the stripped Strings, null if null array input

equals
```
public static boolean equals(String str1,
                             String str2)
```
Compares two Strings, returning true if they are equal.

nulls are handled without exceptions. Two null references are considered to be equal. The comparison is case sensitive.
```
 StringUtils.equals(null, null)   = true
 StringUtils.equals(null, "abc")  = false
 StringUtils.equals("abc", null)  = false
 StringUtils.equals("abc", "abc") = true
 StringUtils.equals("abc", "ABC") = false
 
```
Parameters:

str1 - the first String, may be null

str2 - the second String, may be null

Returns:

true if the Strings are equal, case sensitive, or both null

See Also:

String.equals(Object)

equalsOfAny

public static boolean equalsOfAny(String primary,
                                  String... strings)

Compares the given string against the list of Strings, returning true if they contain this string.

nulls are handled without exceptions. Two null references are considered to be equal. The comparison is case sensitive.

 StringUtils.equals(null, null, "abc")   = true
 StringUtils.equals(null, "abc", "bcd")  = false
 StringUtils.equals("abc", null, "abcd")  = false
 StringUtils.equals("abc", "abc", "bcd") = true
 StringUtils.equals("abc", "ABC", "bcd", "cdf") = false

Parameters:: primary - the primary; strings - the list of of String, may contain null
Returns:: true if they contain this string, case sensitive.
See Also:: String.equals(Object)

equalsIgnoreCase

public static boolean equalsIgnoreCase(String str1,
                                       String str2)

Compares two Strings, returning true if they are equal ignoring the case.

nulls are handled without exceptions. Two null references are considered equal. Comparison is case insensitive.

 StringUtils.equalsIgnoreCase(null, null)   = true
 StringUtils.equalsIgnoreCase(null, "abc")  = false
 StringUtils.equalsIgnoreCase("abc", null)  = false
 StringUtils.equalsIgnoreCase("abc", "abc") = true
 StringUtils.equalsIgnoreCase("abc", "ABC") = true

Parameters:: str1 - the first String, may be null; str2 - the second String, may be null
Returns:: true if the Strings are equal, case insensitive, or both null
See Also:: String.equalsIgnoreCase(String)

equalsOfAnyIgnoreCase

public static boolean equalsOfAnyIgnoreCase(String primary,
                                            String... strings)

Compares the given string against the list of Strings, returning true if they contain this string.

nulls are handled without exceptions. Two null references are considered to be equal. The comparison is case insensitive.

 StringUtils.equals(null, null, "abc")   = true
 StringUtils.equals(null, "abc", "bcd")  = false
 StringUtils.equals("abc", null, "abcd")  = false
 StringUtils.equals("abc", "abc", "bcd") = true
 StringUtils.equals("abc", "ABC", "bcd", "cdf") = false

Parameters:: primary - the primary; strings - the list of of String, may contain null
Returns:: true if they contain this string, case insensitive.
See Also:: String.equals(Object)

indexOf
```
public static int indexOf(String str,
                          char searchChar)
```
Finds the first index within a String, handling null. This method uses String.indexOf(int).

A null or empty ("") String will return INDEX_NOT_FOUND (-1).
```
 StringUtils.indexOf(null, *)         = -1
 StringUtils.indexOf("", *)           = -1
 StringUtils.indexOf("aabaabaa", 'a') = 0
 StringUtils.indexOf("aabaabaa", 'b') = 2
 
```
Parameters:

str - the String to check, may be null

searchChar - the character to find

Returns:

the first index of the search character, -1 if no match or null string input

Since:

2.0

indexOf
```
public static int indexOf(String str,
                          char searchChar,
                          int startPos)
```
Finds the first index within a String from a start position, handling null. This method uses String.indexOf(int, int).

A null or empty ("") String will return (INDEX_NOT_FOUND) -1. A negative start position is treated as zero. A start position greater than the string length returns -1.
```
 StringUtils.indexOf(null, *, *)          = -1
 StringUtils.indexOf("", *, *)            = -1
 StringUtils.indexOf("aabaabaa", 'b', 0)  = 2
 StringUtils.indexOf("aabaabaa", 'b', 3)  = 5
 StringUtils.indexOf("aabaabaa", 'b', 9)  = -1
 StringUtils.indexOf("aabaabaa", 'b', -1) = 2
 
```
Parameters:

str - the String to check, may be null

searchChar - the character to find

startPos - the start position, negative treated as zero

Returns:

the first index of the search character, -1 if no match or null string input

Since:

2.0

indexOf

public static int indexOf(String str,
                          String searchStr)

Finds the first index within a String, handling null. This method uses String.indexOf(String).

A null String will return -1.

 StringUtils.indexOf(null, *)          = -1
 StringUtils.indexOf(*, null)          = -1
 StringUtils.indexOf("", "")           = 0
 StringUtils.indexOf("", *)            = -1 (except when * = "")
 StringUtils.indexOf("aabaabaa", "a")  = 0
 StringUtils.indexOf("aabaabaa", "b")  = 2
 StringUtils.indexOf("aabaabaa", "ab") = 1
 StringUtils.indexOf("aabaabaa", "")   = 0

Parameters:: str - the String to check, may be null; searchStr - the String to find, may be null
Returns:: the first index of the search String, -1 if no match or null string input
Since:: 2.0

ordinalIndexOf

public static int ordinalIndexOf(String str,
                                 String searchStr,
                                 int ordinal)

Finds the n-th index within a String, handling null. This method uses String.indexOf(String).

A null String will return -1.

 StringUtils.ordinalIndexOf(null, *, *)          = -1
 StringUtils.ordinalIndexOf(*, null, *)          = -1
 StringUtils.ordinalIndexOf("", "", *)           = 0
 StringUtils.ordinalIndexOf("aabaabaa", "a", 1)  = 0
 StringUtils.ordinalIndexOf("aabaabaa", "a", 2)  = 1
 StringUtils.ordinalIndexOf("aabaabaa", "b", 1)  = 2
 StringUtils.ordinalIndexOf("aabaabaa", "b", 2)  = 5
 StringUtils.ordinalIndexOf("aabaabaa", "ab", 1) = 1
 StringUtils.ordinalIndexOf("aabaabaa", "ab", 2) = 4
 StringUtils.ordinalIndexOf("aabaabaa", "", 1)   = 0
 StringUtils.ordinalIndexOf("aabaabaa", "", 2)   = 0

Note that 'head(String str, int n)' may be implemented as:

 str.substring(0, lastOrdinalIndexOf(str, "\n", n))

Parameters:: str - the String to check, may be null; searchStr - the String to find, may be null; ordinal - the n-th searchStr to find
Returns:: the n-th index of the search String, -1 ( INDEX_NOT_FOUND) if no match or null string input
Since:: 2.1

indexOf

public static int indexOf(String str,
                          String searchStr,
                          int startPos)

Finds the first index within a String, handling null. This method uses String.indexOf(String, int).

A null String will return -1. A negative start position is treated as zero. An empty ("") search String always matches. A start position greater than the string length only matches an empty search String.

 StringUtils.indexOf(null, *, *)          = -1
 StringUtils.indexOf(*, null, *)          = -1
 StringUtils.indexOf("", "", 0)           = 0
 StringUtils.indexOf("", *, 0)            = -1 (except when * = "")
 StringUtils.indexOf("aabaabaa", "a", 0)  = 0
 StringUtils.indexOf("aabaabaa", "b", 0)  = 2
 StringUtils.indexOf("aabaabaa", "ab", 0) = 1
 StringUtils.indexOf("aabaabaa", "b", 3)  = 5
 StringUtils.indexOf("aabaabaa", "b", 9)  = -1
 StringUtils.indexOf("aabaabaa", "b", -1) = 2
 StringUtils.indexOf("aabaabaa", "", 2)   = 2
 StringUtils.indexOf("abc", "", 9)        = 3

Parameters:: str - the String to check, may be null; searchStr - the String to find, may be null; startPos - the start position, negative treated as zero
Returns:: the first index of the search String, -1 if no match or null string input
Since:: 2.0

indexOfIgnoreCase

public static int indexOfIgnoreCase(String str,
                                    String searchStr)

Case in-sensitive find of the first index within a String.

 StringUtils.indexOfIgnoreCase(null, *)          = -1
 StringUtils.indexOfIgnoreCase(*, null)          = -1
 StringUtils.indexOfIgnoreCase("", "")           = 0
 StringUtils.indexOfIgnoreCase("aabaabaa", "a")  = 0
 StringUtils.indexOfIgnoreCase("aabaabaa", "b")  = 2
 StringUtils.indexOfIgnoreCase("aabaabaa", "ab") = 1

Parameters:: str - the String to check, may be null; searchStr - the String to find, may be null
Returns:: the first index of the search String, -1 if no match or null string input
Since:: 2.5

indexOfIgnoreCase

public static int indexOfIgnoreCase(String str,
                                    String searchStr,
                                    int startPos)

Case in-sensitive find of the first index within a String from the specified position.

 StringUtils.indexOfIgnoreCase(null, *, *)          = -1
 StringUtils.indexOfIgnoreCase(*, null, *)          = -1
 StringUtils.indexOfIgnoreCase("", "", 0)           = 0
 StringUtils.indexOfIgnoreCase("aabaabaa", "A", 0)  = 0
 StringUtils.indexOfIgnoreCase("aabaabaa", "B", 0)  = 2
 StringUtils.indexOfIgnoreCase("aabaabaa", "AB", 0) = 1
 StringUtils.indexOfIgnoreCase("aabaabaa", "B", 3)  = 5
 StringUtils.indexOfIgnoreCase("aabaabaa", "B", 9)  = -1
 StringUtils.indexOfIgnoreCase("aabaabaa", "B", -1) = 2
 StringUtils.indexOfIgnoreCase("aabaabaa", "", 2)   = 2
 StringUtils.indexOfIgnoreCase("abc", "", 9)        = 3

Parameters:: str - the String to check, may be null; searchStr - the String to find, may be null; startPos - the start position, negative treated as zero
Returns:: the first index of the search String, -1 if no match or null string input
Since:: 2.5

lastIndexOf
```
public static int lastIndexOf(String str,
                              char searchChar)
```
Finds the last index within a String, handling null. This method uses String.lastIndexOf(int).

A null or empty ("") String will return -1.
```
 StringUtils.lastIndexOf(null, *)         = -1
 StringUtils.lastIndexOf("", *)           = -1
 StringUtils.lastIndexOf("aabaabaa", 'a') = 7
 StringUtils.lastIndexOf("aabaabaa", 'b') = 5
 
```
Parameters:

str - the String to check, may be null

searchChar - the character to find

Returns:

the last index of the search character, -1 if no match or null string input

Since:

2.0

lastIndexOf

public static int lastIndexOf(String str,
                              char searchChar,
                              int startPos)

Finds the last index within a String from a start position, handling null. This method uses String.lastIndexOf(int, int).

A null or empty ("") String will return -1. A negative start position returns -1. A start position greater than the string length searches the whole string.

 StringUtils.lastIndexOf(null, *, *)          = -1
 StringUtils.lastIndexOf("", *,  *)           = -1
 StringUtils.lastIndexOf("aabaabaa", 'b', 8)  = 5
 StringUtils.lastIndexOf("aabaabaa", 'b', 4)  = 2
 StringUtils.lastIndexOf("aabaabaa", 'b', 0)  = -1
 StringUtils.lastIndexOf("aabaabaa", 'b', 9)  = 5
 StringUtils.lastIndexOf("aabaabaa", 'b', -1) = -1
 StringUtils.lastIndexOf("aabaabaa", 'a', 0)  = 0

Parameters:: str - the String to check, may be null; searchChar - the character to find; startPos - the start position
Returns:: the last index of the search character, -1 if no match or null string input
Since:: 2.0

lastIndexOf

public static int lastIndexOf(String str,
                              String searchStr)

Finds the last index within a String, handling null. This method uses String.lastIndexOf(String).

A null String will return -1.

 StringUtils.lastIndexOf(null, *)          = -1
 StringUtils.lastIndexOf(*, null)          = -1
 StringUtils.lastIndexOf("", "")           = 0
 StringUtils.lastIndexOf("aabaabaa", "a")  = 7
 StringUtils.lastIndexOf("aabaabaa", "b")  = 5
 StringUtils.lastIndexOf("aabaabaa", "ab") = 4
 StringUtils.lastIndexOf("aabaabaa", "")   = 8

Parameters:: str - the String to check, may be null; searchStr - the String to find, may be null
Returns:: the last index of the search String, -1 if no match or null string input
Since:: 2.0

lastOrdinalIndexOf

public static int lastOrdinalIndexOf(String str,
                                     String searchStr,
                                     int ordinal)

Finds the n-th last index within a String, handling null. This method uses String.lastIndexOf(String).

A null String will return -1.

 StringUtils.lastOrdinalIndexOf(null, *, *)          = -1
 StringUtils.lastOrdinalIndexOf(*, null, *)          = -1
 StringUtils.lastOrdinalIndexOf("", "", *)           = 0
 StringUtils.lastOrdinalIndexOf("aabaabaa", "a", 1)  = 7
 StringUtils.lastOrdinalIndexOf("aabaabaa", "a", 2)  = 6
 StringUtils.lastOrdinalIndexOf("aabaabaa", "b", 1)  = 5
 StringUtils.lastOrdinalIndexOf("aabaabaa", "b", 2)  = 2
 StringUtils.lastOrdinalIndexOf("aabaabaa", "ab", 1) = 4
 StringUtils.lastOrdinalIndexOf("aabaabaa", "ab", 2) = 1
 StringUtils.lastOrdinalIndexOf("aabaabaa", "", 1)   = 8
 StringUtils.lastOrdinalIndexOf("aabaabaa", "", 2)   = 8

Note that 'tail(String str, int n)' may be implemented as:

 str.substring(lastOrdinalIndexOf(str, "\n", n) + 1)

Parameters:: str - the String to check, may be null; searchStr - the String to find, may be null; ordinal - the n-th last searchStr to find
Returns:: the n-th last index of the search String, -1 ( INDEX_NOT_FOUND) if no match or null string input
Since:: 2.5

lastIndexOf

public static int lastIndexOf(String str,
                              String searchStr,
                              int startPos)

Finds the first index within a String, handling null. This method uses String.lastIndexOf(String, int).

A null String will return -1. A negative start position returns -1. An empty ("") search String always matches unless the start position is negative. A start position greater than the string length searches the whole string.

 StringUtils.lastIndexOf(null, *, *)          = -1
 StringUtils.lastIndexOf(*, null, *)          = -1
 StringUtils.lastIndexOf("aabaabaa", "a", 8)  = 7
 StringUtils.lastIndexOf("aabaabaa", "b", 8)  = 5
 StringUtils.lastIndexOf("aabaabaa", "ab", 8) = 4
 StringUtils.lastIndexOf("aabaabaa", "b", 9)  = 5
 StringUtils.lastIndexOf("aabaabaa", "b", -1) = -1
 StringUtils.lastIndexOf("aabaabaa", "a", 0)  = 0
 StringUtils.lastIndexOf("aabaabaa", "b", 0)  = -1

Parameters:: str - the String to check, may be null; searchStr - the String to find, may be null; startPos - the start position, negative treated as zero
Returns:: the first index of the search String, -1 if no match or null string input
Since:: 2.0

lastIndexOfIgnoreCase
```
public static int lastIndexOfIgnoreCase(String str,
                                        String searchStr)
```
Case in-sensitive find of the last index within a String.

A null String will return -1. A negative start position returns -1. An empty ("") search String always matches unless the start position is negative. A start position greater than the string length searches the whole string.
```
 StringUtils.lastIndexOfIgnoreCase(null, *)          = -1
 StringUtils.lastIndexOfIgnoreCase(*, null)          = -1
 StringUtils.lastIndexOfIgnoreCase("aabaabaa", "A")  = 7
 StringUtils.lastIndexOfIgnoreCase("aabaabaa", "B")  = 5
 StringUtils.lastIndexOfIgnoreCase("aabaabaa", "AB") = 4
 
```
Parameters:

str - the String to check, may be null

searchStr - the String to find, may be null

Returns:

the first index of the search String, -1 if no match or null string input

Since:

2.5

lastIndexOfIgnoreCase

public static int lastIndexOfIgnoreCase(String str,
                                        String searchStr,
                                        int startPos)

Case in-sensitive find of the last index within a String from the specified position.

 StringUtils.lastIndexOfIgnoreCase(null, *, *)          = -1
 StringUtils.lastIndexOfIgnoreCase(*, null, *)          = -1
 StringUtils.lastIndexOfIgnoreCase("aabaabaa", "A", 8)  = 7
 StringUtils.lastIndexOfIgnoreCase("aabaabaa", "B", 8)  = 5
 StringUtils.lastIndexOfIgnoreCase("aabaabaa", "AB", 8) = 4
 StringUtils.lastIndexOfIgnoreCase("aabaabaa", "B", 9)  = 5
 StringUtils.lastIndexOfIgnoreCase("aabaabaa", "B", -1) = -1
 StringUtils.lastIndexOfIgnoreCase("aabaabaa", "A", 0)  = 0
 StringUtils.lastIndexOfIgnoreCase("aabaabaa", "B", 0)  = -1

Parameters:: str - the String to check, may be null; searchStr - the String to find, may be null; startPos - the start position
Returns:: the first index of the search String, -1 if no match or null string input
Since:: 2.5

contains
```
public static boolean contains(String str,
                               char searchChar)
```
Checks if String contains a search character, handling null. This method uses String.indexOf(int).

A null or empty ("") String will return false.
```
 StringUtils.contains(null, *)    = false
 StringUtils.contains("", *)      = false
 StringUtils.contains("abc", 'a') = true
 StringUtils.contains("abc", 'z') = false
 
```
Parameters:

str - the String to check, may be null

searchChar - the character to find

Returns:

true if the String contains the search character, false if not or null string input

Since:

2.0

contains

public static boolean contains(String str,
                               String searchStr)

Checks if String contains a search String, handling null. This method uses String.indexOf(String).

A null String will return false.

 StringUtils.contains(null, *)     = false
 StringUtils.contains(*, null)     = false
 StringUtils.contains("", "")      = true
 StringUtils.contains("abc", "")   = true
 StringUtils.contains("abc", "a")  = true
 StringUtils.contains("abc", "z")  = false

Parameters:: str - the String to check, may be null; searchStr - the String to find, may be null
Returns:: true if the String contains the search String, false if not or null string input
Since:: 2.0

containsIgnoreCase

public static boolean containsIgnoreCase(String str,
                                         String searchStr)

Checks if String contains a search String irrespective of case, handling null. Case-insensitivity is defined as by String.equalsIgnoreCase(String).

A null String will return false.

 StringUtils.contains(null, *) = false
 StringUtils.contains(*, null) = false
 StringUtils.contains("", "") = true
 StringUtils.contains("abc", "") = true
 StringUtils.contains("abc", "a") = true
 StringUtils.contains("abc", "z") = false
 StringUtils.contains("abc", "A") = true
 StringUtils.contains("abc", "Z") = false

Parameters:: str - the String to check, may be null; searchStr - the String to find, may be null
Returns:: true if the String contains the search String irrespective of case or false if not or null string input

indexOfAny

public static int indexOfAny(String str,
                             char[] searchChars)

Search a String to find the first index of any character in the given set of characters.

A null String will return -1. A null or zero length search array will return -1 .

 StringUtils.indexOfAny(null, *)                = -1
 StringUtils.indexOfAny("", *)                  = -1
 StringUtils.indexOfAny(*, null)                = -1
 StringUtils.indexOfAny(*, [])                  = -1
 StringUtils.indexOfAny("zzabyycdxx",['z','a']) = 0
 StringUtils.indexOfAny("zzabyycdxx",['b','y']) = 3
 StringUtils.indexOfAny("aba", ['z'])           = -1

Parameters:: str - the String to check, may be null; searchChars - the chars to search for, may be null
Returns:: the index of any of the chars, -1 if no match or null input
Since:: 2.0

isHighSurrogate
```
public static boolean isHighSurrogate(char ch)
```
Indicates whether ch is a high- (or leading-) surrogate code unit that is used for representing supplementary characters in UTF-16 encoding.

Parameters:

ch - the character to test.

Returns:

true if ch is a high-surrogate code unit; false otherwise.

indexOfAny

public static int indexOfAny(String str,
                             String searchChars)

Search a String to find the first index of any character in the given set of characters.

A null String will return -1. A null search string will return -1.

 StringUtils.indexOfAny(null, *)            = -1
 StringUtils.indexOfAny("", *)              = -1
 StringUtils.indexOfAny(*, null)            = -1
 StringUtils.indexOfAny(*, "")              = -1
 StringUtils.indexOfAny("zzabyycdxx", "za") = 0
 StringUtils.indexOfAny("zzabyycdxx", "by") = 3
 StringUtils.indexOfAny("aba","z")          = -1

Parameters:: str - the String to check, may be null; searchChars - the chars to search for, may be null
Returns:: the index of any of the chars, -1 if no match or null input
Since:: 2.0

containsAny

public static boolean containsAny(String str,
                                  char[] searchChars)

Checks if the String contains any character in the given set of characters.

A null String will return false. A null or zero length search array will return false.

 StringUtils.containsAny(null, *)                = false
 StringUtils.containsAny("", *)                  = false
 StringUtils.containsAny(*, null)                = false
 StringUtils.containsAny(*, [])                  = false
 StringUtils.containsAny("zzabyycdxx",['z','a']) = true
 StringUtils.containsAny("zzabyycdxx",['b','y']) = true
 StringUtils.containsAny("aba", ['z'])           = false

Parameters:: str - the String to check, may be null; searchChars - the chars to search for, may be null
Returns:: the true if any of the chars are found, false if no match or null input
Since:: 2.4

containsAny

public static boolean containsAny(String str,
                                  String searchChars)

Checks if the String contains any character in the given set of characters.

A null String will return false. A null search string will return false.

 StringUtils.containsAny(null, *)            = false
 StringUtils.containsAny("", *)              = false
 StringUtils.containsAny(*, null)            = false
 StringUtils.containsAny(*, "")              = false
 StringUtils.containsAny("zzabyycdxx", "za") = true
 StringUtils.containsAny("zzabyycdxx", "by") = true
 StringUtils.containsAny("aba","z")          = false

Parameters:: str - the String to check, may be null; searchChars - the chars to search for, may be null
Returns:: the true if any of the chars are found, false if no match or null input
Since:: 2.4

indexOfAnyBut

public static int indexOfAnyBut(String str,
                                char[] searchChars)

Search a String to find the first index of any character not in the given set of characters.

A null String will return -1. A null or zero length search array will return -1 .

 StringUtils.indexOfAnyBut(null, *)                              = -1
 StringUtils.indexOfAnyBut("", *)                                = -1
 StringUtils.indexOfAnyBut(*, null)                              = -1
 StringUtils.indexOfAnyBut(*, [])                                = -1
 StringUtils.indexOfAnyBut("zzabyycdxx", new char[] {'z', 'a'} ) = 3
 StringUtils.indexOfAnyBut("aba", new char[] {'z'} )             = 0
 StringUtils.indexOfAnyBut("aba", new char[] {'a', 'b'} )        = -1

Parameters:: str - the String to check, may be null; searchChars - the chars to search for, may be null
Returns:: the index of any of the chars, -1 if no match or null input
Since:: 2.0

indexOfAnyBut

public static int indexOfAnyBut(String str,
                                String searchChars)

Search a String to find the first index of any character not in the given set of characters.

A null String will return -1. A null or empty search string will return -1.

 StringUtils.indexOfAnyBut(null, *)            = -1
 StringUtils.indexOfAnyBut("", *)              = -1
 StringUtils.indexOfAnyBut(*, null)            = -1
 StringUtils.indexOfAnyBut(*, "")              = -1
 StringUtils.indexOfAnyBut("zzabyycdxx", "za") = 3
 StringUtils.indexOfAnyBut("zzabyycdxx", "")   = -1
 StringUtils.indexOfAnyBut("aba","ab")         = -1

Parameters:: str - the String to check, may be null; searchChars - the chars to search for, may be null
Returns:: the index of any of the chars, -1 if no match or null input
Since:: 2.0

containsOnly

public static boolean containsOnly(String str,
                                   char[] valid)

Checks if the String contains only certain characters.

A null String will return false. A null valid character array will return false. An empty String (length()=0) always returns true.

 StringUtils.containsOnly(null, *)       = false
 StringUtils.containsOnly(*, null)       = false
 StringUtils.containsOnly("", *)         = true
 StringUtils.containsOnly("ab", '')      = false
 StringUtils.containsOnly("abab", 'abc') = true
 StringUtils.containsOnly("ab1", 'abc')  = false
 StringUtils.containsOnly("abz", 'abc')  = false

Parameters:: str - the String to check, may be null; valid - an array of valid chars, may be null
Returns:: true if it only contains valid chars and is non-null

containsOnly

public static boolean containsOnly(String str,
                                   String validChars)

Checks if the String contains only certain characters.

A null String will return false. A null valid character String will return false. An empty String (length()=0) always returns true.

 StringUtils.containsOnly(null, *)       = false
 StringUtils.containsOnly(*, null)       = false
 StringUtils.containsOnly("", *)         = true
 StringUtils.containsOnly("ab", "")      = false
 StringUtils.containsOnly("abab", "abc") = true
 StringUtils.containsOnly("ab1", "abc")  = false
 StringUtils.containsOnly("abz", "abc")  = false

Parameters:: str - the String to check, may be null; validChars - a String of valid chars, may be null
Returns:: true if it only contains valid chars and is non-null
Since:: 2.0

containsNone

public static boolean containsNone(String str,
                                   char[] searchChars)

Checks that the String does not contain certain characters.

A null String will return true. A null invalid character array will return true. An empty String (length()=0) always returns true.

 StringUtils.containsNone(null, *)       = true
 StringUtils.containsNone(*, null)       = true
 StringUtils.containsNone("", *)         = true
 StringUtils.containsNone("ab", '')      = true
 StringUtils.containsNone("abab", 'xyz') = true
 StringUtils.containsNone("ab1", 'xyz')  = true
 StringUtils.containsNone("abz", 'xyz')  = false

Parameters:: str - the String to check, may be null; searchChars - an array of invalid chars, may be null
Returns:: true if it contains none of the invalid chars, or is null
Since:: 2.0

containsNone

public static boolean containsNone(String str,
                                   String invalidChars)

Checks that the String does not contain certain characters.

A null String will return true. A null invalid character array will return true. An empty String ("") always returns true.

 StringUtils.containsNone(null, *)       = true
 StringUtils.containsNone(*, null)       = true
 StringUtils.containsNone("", *)         = true
 StringUtils.containsNone("ab", "")      = true
 StringUtils.containsNone("abab", "xyz") = true
 StringUtils.containsNone("ab1", "xyz")  = true
 StringUtils.containsNone("abz", "xyz")  = false

Parameters:: str - the String to check, may be null; invalidChars - a String of invalid chars, may be null
Returns:: true if it contains none of the invalid chars, or is null
Since:: 2.0

indexOfAny

public static int indexOfAny(String str,
                             String[] searchStrs)

Find the first index of any of a set of potential substrings.

A null String will return -1. A null or zero length search array will return -1 . A null search array entry will be ignored, but a search array containing "" will return 0 if str is not null. This method uses String.indexOf(String).

 StringUtils.indexOfAny(null, *)                     = -1
 StringUtils.indexOfAny(*, null)                     = -1
 StringUtils.indexOfAny(*, [])                       = -1
 StringUtils.indexOfAny("zzabyycdxx", ["ab","cd"])   = 2
 StringUtils.indexOfAny("zzabyycdxx", ["cd","ab"])   = 2
 StringUtils.indexOfAny("zzabyycdxx", ["mn","op"])   = -1
 StringUtils.indexOfAny("zzabyycdxx", ["zab","aby"]) = 1
 StringUtils.indexOfAny("zzabyycdxx", [""])          = 0
 StringUtils.indexOfAny("", [""])                    = 0
 StringUtils.indexOfAny("", ["a"])                   = -1

Parameters:: str - the String to check, may be null; searchStrs - the Strings to search for, may be null
Returns:: the first index of any of the searchStrs in str, -1 if no match

lastIndexOfAny

public static int lastIndexOfAny(String str,
                                 String[] searchStrs)

Find the latest index of any of a set of potential substrings.

A null String will return -1. A null search array will return -1. A null or zero length search array entry will be ignored, but a search array containing "" will return the length of str if str is not null. This method uses String.indexOf(String)

 StringUtils.lastIndexOfAny(null, *)                   = -1
 StringUtils.lastIndexOfAny(*, null)                   = -1
 StringUtils.lastIndexOfAny(*, [])                     = -1
 StringUtils.lastIndexOfAny(*, [null])                 = -1
 StringUtils.lastIndexOfAny("zzabyycdxx", ["ab","cd"]) = 6
 StringUtils.lastIndexOfAny("zzabyycdxx", ["cd","ab"]) = 6
 StringUtils.lastIndexOfAny("zzabyycdxx", ["mn","op"]) = -1
 StringUtils.lastIndexOfAny("zzabyycdxx", ["mn","op"]) = -1
 StringUtils.lastIndexOfAny("zzabyycdxx", ["mn",""])   = 10

Parameters:: str - the String to check, may be null; searchStrs - the Strings to search for, may be null
Returns:: the last index of any of the Strings, -1 if no match

substring
```
public static String substring(String str,
                               int start)
```
Gets a substring from the specified String avoiding exceptions.

A negative start position can be used to start n characters from the end of the String.

A null String will return null. An empty ("") String will return "".
```
 StringUtils.substring(null, *)   = null
 StringUtils.substring("", *)     = ""
 StringUtils.substring("abc", 0)  = "abc"
 StringUtils.substring("abc", 2)  = "c"
 StringUtils.substring("abc", 4)  = ""
 StringUtils.substring("abc", -2) = "bc"
 StringUtils.substring("abc", -4) = "abc"
 
```
Parameters:

str - the String to get the substring from, may be null

start - the position to start from, negative means count back from the end of the String by this many characters

Returns:

substring from start position, null if null String input

substring
```
public static String substring(String str,
                               int start,
                               int end)
```
Gets a substring from the specified String avoiding exceptions.

A negative start position can be used to start/end n characters from the end of the String.

The returned substring starts with the character in the start position and ends before the end position. All position counting is zero-based -- i.e., to start at the beginning of the string use start = 0. Negative start and end positions can be used to specify offsets relative to the end of the String.

If start is not strictly to the left of end, "" is returned.
```
 StringUtils.substring(null, *, *)    = null
 StringUtils.substring("", * ,  *)    = "";
 StringUtils.substring("abc", 0, 2)   = "ab"
 StringUtils.substring("abc", 2, 0)   = ""
 StringUtils.substring("abc", 2, 4)   = "c"
 StringUtils.substring("abc", 4, 6)   = ""
 StringUtils.substring("abc", 2, 2)   = ""
 StringUtils.substring("abc", -2, -1) = "b"
 StringUtils.substring("abc", -4, 2)  = "ab"
 
```
Parameters:

str - the String to get the substring from, may be null

start - the position to start from, negative means count back from the end of the String by this many characters

end - the position to end at (exclusive), negative means count back from the end of the String by this many characters

Returns:

substring from start position to end positon, null if null String input

left
```
public static String left(String str,
                          int len)
```
Gets the leftmost len characters of a String.

If len characters are not available, or the String is null, the String will be returned without an exception. An empty String is returned if len is negative.
```
 StringUtils.left(null, *)    = null
 StringUtils.left(*, -ve)     = ""
 StringUtils.left("", *)      = ""
 StringUtils.left("abc", 0)   = ""
 StringUtils.left("abc", 2)   = "ab"
 StringUtils.left("abc", 4)   = "abc"
 
```
Parameters:

str - the String to get the leftmost characters from, may be null

len - the length of the required String

Returns:

the leftmost characters, null if null String input

right
```
public static String right(String str,
                           int len)
```
Gets the rightmost len characters of a String.

If len characters are not available, or the String is null, the String will be returned without an an exception. An empty String is returned if len is negative.
```
 StringUtils.right(null, *)    = null
 StringUtils.right(*, -ve)     = ""
 StringUtils.right("", *)      = ""
 StringUtils.right("abc", 0)   = ""
 StringUtils.right("abc", 2)   = "bc"
 StringUtils.right("abc", 4)   = "abc"
 
```
Parameters:

str - the String to get the rightmost characters from, may be null

len - the length of the required String

Returns:

the rightmost characters, null if null String input

mid
```
public static String mid(String str,
                         int pos,
                         int len)
```
Gets len characters from the middle of a String.

If len characters are not available, the remainder of the String will be returned without an exception. If the String is null, null will be returned. An empty String is returned if len is negative or exceeds the length of str.
```
 StringUtils.mid(null, *, *)    = null
 StringUtils.mid(*, *, -ve)     = ""
 StringUtils.mid("", 0, *)      = ""
 StringUtils.mid("abc", 0, 2)   = "ab"
 StringUtils.mid("abc", 0, 4)   = "abc"
 StringUtils.mid("abc", 2, 4)   = "c"
 StringUtils.mid("abc", 4, 2)   = ""
 StringUtils.mid("abc", -2, 2)  = "ab"
 
```
Parameters:

str - the String to get the characters from, may be null

pos - the position to start from, negative treated as zero

len - the length of the required String

Returns:

the middle characters, null if null String input

substringBefore

public static String substringBefore(String str,
                                     String separator)

Gets the substring before the first occurrence of a separator. The separator is not returned.

A null string input will return null. An empty ("") string input will return the empty string. A null separator will return the input string.

If nothing is found, the string input is returned.

 StringUtils.substringBefore(null, *)      = null
 StringUtils.substringBefore("", *)        = ""
 StringUtils.substringBefore("abc", "a")   = ""
 StringUtils.substringBefore("abcba", "b") = "a"
 StringUtils.substringBefore("abc", "c")   = "ab"
 StringUtils.substringBefore("abc", "d")   = "abc"
 StringUtils.substringBefore("abc", "")    = ""
 StringUtils.substringBefore("abc", null)  = "abc"

Parameters:: str - the String to get a substring from, may be null; separator - the String to search for, may be null
Returns:: the substring before the first occurrence of the separator, null if null String input
Since:: 2.0

substringAfter

public static String substringAfter(String str,
                                    String separator)

Gets the substring after the first occurrence of a separator. The separator is not returned.

A null string input will return null. An empty ("") string input will return the empty string. A null separator will return the empty string if the input string is not null.

If nothing is found, the empty string is returned.

 StringUtils.substringAfter(null, *)      = null
 StringUtils.substringAfter("", *)        = ""
 StringUtils.substringAfter(*, null)      = ""
 StringUtils.substringAfter("abc", "a")   = "bc"
 StringUtils.substringAfter("abcba", "b") = "cba"
 StringUtils.substringAfter("abc", "c")   = ""
 StringUtils.substringAfter("abc", "d")   = ""
 StringUtils.substringAfter("abc", "")    = "abc"

Parameters:: str - the String to get a substring from, may be null; separator - the String to search for, may be null
Returns:: the substring after the first occurrence of the separator, null if null String input
Since:: 2.0

substringBeforeLast

public static String substringBeforeLast(String str,
                                         String separator)

Gets the substring before the last occurrence of a separator. The separator is not returned.

A null string input will return null. An empty ("") string input will return the empty string. An empty or null separator will return the input string.

If nothing is found, the string input is returned.

 StringUtils.substringBeforeLast(null, *)      = null
 StringUtils.substringBeforeLast("", *)        = ""
 StringUtils.substringBeforeLast("abcba", "b") = "abc"
 StringUtils.substringBeforeLast("abc", "c")   = "ab"
 StringUtils.substringBeforeLast("a", "a")     = ""
 StringUtils.substringBeforeLast("a", "z")     = "a"
 StringUtils.substringBeforeLast("a", null)    = "a"
 StringUtils.substringBeforeLast("a", "")      = "a"

Parameters:: str - the String to get a substring from, may be null; separator - the String to search for, may be null
Returns:: the substring before the last occurrence of the separator, null if null String input
Since:: 2.0

substringAfterLast

public static String substringAfterLast(String str,
                                        String separator)

Gets the substring after the last occurrence of a separator. The separator is not returned.

A null string input will return null. An empty ("") string input will return the empty string. An empty or null separator will return the empty string if the input string is not null.

If nothing is found, the empty string is returned.

 StringUtils.substringAfterLast(null, *)      = null
 StringUtils.substringAfterLast("", *)        = ""
 StringUtils.substringAfterLast(*, "")        = ""
 StringUtils.substringAfterLast(*, null)      = ""
 StringUtils.substringAfterLast("abc", "a")   = "bc"
 StringUtils.substringAfterLast("abcba", "b") = "a"
 StringUtils.substringAfterLast("abc", "c")   = ""
 StringUtils.substringAfterLast("a", "a")     = ""
 StringUtils.substringAfterLast("a", "z")     = ""

Parameters:: str - the String to get a substring from, may be null; separator - the String to search for, may be null
Returns:: the substring after the last occurrence of the separator, null if null String input
Since:: 2.0

substringBetween

public static String substringBetween(String str,
                                      String tag)

Gets the String that is nested in between two instances of the same String.

A null input String returns null. A null tag returns null.

 StringUtils.substringBetween(null, *)            = null
 StringUtils.substringBetween("", "")             = ""
 StringUtils.substringBetween("", "tag")          = null
 StringUtils.substringBetween("tagabctag", null)  = null
 StringUtils.substringBetween("tagabctag", "")    = ""
 StringUtils.substringBetween("tagabctag", "tag") = "abc"

Parameters:: str - the String containing the substring, may be null; tag - the String before and after the substring, may be null
Returns:: the substring, null if no match
Since:: 2.0

substringBetween

public static String substringBetween(String str,
                                      String open,
                                      String close)

Gets the String that is nested in between two Strings. Only the first match is returned.

A null input String returns null. A null open/close returns null (no match). An empty ("") open and close returns an empty string.

 StringUtils.substringBetween("wx[b]yz", "[", "]") = "b"
 StringUtils.substringBetween(null, *, *)          = null
 StringUtils.substringBetween(*, null, *)          = null
 StringUtils.substringBetween(*, *, null)          = null
 StringUtils.substringBetween("", "", "")          = ""
 StringUtils.substringBetween("", "", "]")         = null
 StringUtils.substringBetween("", "[", "]")        = null
 StringUtils.substringBetween("yabcz", "", "")     = ""
 StringUtils.substringBetween("yabcz", "y", "z")   = "abc"
 StringUtils.substringBetween("yabczyabcz", "y", "z")   = "abc"

Parameters:: str - the String containing the substring, may be null; open - the String before the substring, may be null; close - the String after the substring, may be null
Returns:: the substring, null if no match
Since:: 2.0

substringsBetween
```
public static String[] substringsBetween(String str,
                                         String open,
                                         String close)
```
Searches a String for substrings delimited by a start and end tag, returning all matching substrings in an array.

A null input String returns null. A null open/close returns null (no match). An empty ("") open/close returns null (no match).
```
 StringUtils.substringsBetween("[a][b][c]", "[", "]") = ["a","b","c"]
 StringUtils.substringsBetween(null, *, *)            = null
 StringUtils.substringsBetween(*, null, *)            = null
 StringUtils.substringsBetween(*, *, null)            = null
 StringUtils.substringsBetween("", "[", "]")          = []
 
```
Parameters:

str - the String containing the substrings, null returns null, empty returns empty

open - the String identifying the start of the substring, empty returns null

close - the String identifying the end of the substring, empty returns null

Returns:

a String Array of substrings, or null if no match

Since:

2.3

getNestedString

public static String getNestedString(String str,
                                     String tag)

Deprecated. Use the better named substringBetween(String, String). Method will be removed in Commons Lang 3.0.

Gets the String that is nested in between two instances of the same String.

A null input String returns null. A null tag returns null.

 StringUtils.getNestedString(null, *)            = null
 StringUtils.getNestedString("", "")             = ""
 StringUtils.getNestedString("", "tag")          = null
 StringUtils.getNestedString("tagabctag", null)  = null
 StringUtils.getNestedString("tagabctag", "")    = ""
 StringUtils.getNestedString("tagabctag", "tag") = "abc"

Parameters:: str - the String containing nested-string, may be null; tag - the String before and after nested-string, may be null
Returns:: the nested String, null if no match

getNestedString

public static String getNestedString(String str,
                                     String open,
                                     String close)

Deprecated. Use the better named substringBetween(String, String, String). Method will be removed in Commons Lang 3.0.

Gets the String that is nested in between two Strings. Only the first match is returned.

A null input String returns null. A null open/close returns null (no match). An empty ("") open/close returns an empty string.

 StringUtils.getNestedString(null, *, *)          = null
 StringUtils.getNestedString("", "", "")          = ""
 StringUtils.getNestedString("", "", "tag")       = null
 StringUtils.getNestedString("", "tag", "tag")    = null
 StringUtils.getNestedString("yabcz", null, null) = null
 StringUtils.getNestedString("yabcz", "", "")     = ""
 StringUtils.getNestedString("yabcz", "y", "z")   = "abc"
 StringUtils.getNestedString("yabczyabcz", "y", "z")   = "abc"

Parameters:: str - the String containing nested-string, may be null; open - the String before nested-string, may be null; close - the String after nested-string, may be null
Returns:: the nested String, null if no match

split
```
public static String[] split(String str)
```
Splits the provided text into an array, using whitespace as the separator. Whitespace is defined by Character.isWhitespace(char).

The separator is not included in the returned String array. Adjacent separators are treated as one separator. For more control over the split use the StrTokenizer class.

A null input String returns null.
```
 StringUtils.split(null)       = null
 StringUtils.split("")         = []
 StringUtils.split("abc def")  = ["abc", "def"]
 StringUtils.split("abc  def") = ["abc", "def"]
 StringUtils.split(" abc ")    = ["abc"]
 
```
Parameters:

str - the String to parse, may be null

Returns:

an array of parsed Strings, null if null String input

split
```
public static String[] split(String str,
                             char separatorChar)
```
Splits the provided text into an array, separator specified. This is an alternative to using StringTokenizer.

The separator is not included in the returned String array. Adjacent separators are treated as one separator. For more control over the split use the StrTokenizer class.

A null input String returns null.
```
 StringUtils.split(null, *)         = null
 StringUtils.split("", *)           = []
 StringUtils.split("a.b.c", '.')    = ["a", "b", "c"]
 StringUtils.split("a..b.c", '.')   = ["a", "b", "c"]
 StringUtils.split("a:b:c", '.')    = ["a:b:c"]
 StringUtils.split("a b c", ' ')    = ["a", "b", "c"]
 
```
Parameters:

str - the String to parse, may be null

separatorChar - the character used as the delimiter

Returns:

an array of parsed Strings, null if null String input

Since:

2.0

split
```
public static String[] split(String str,
                             String separatorChars)
```
Splits the provided text into an array, separators specified. This is an alternative to using StringTokenizer.

The separator is not included in the returned String array. Adjacent separators are treated as one separator. For more control over the split use the StrTokenizer class.

A null input String returns null. A null separatorChars splits on whitespace.
```
 StringUtils.split(null, *)         = null
 StringUtils.split("", *)           = []
 StringUtils.split("abc def", null) = ["abc", "def"]
 StringUtils.split("abc def", " ")  = ["abc", "def"]
 StringUtils.split("abc  def", " ") = ["abc", "def"]
 StringUtils.split("ab:cd:ef", ":") = ["ab", "cd", "ef"]
 
```
Parameters:

str - the String to parse, may be null

separatorChars - the characters used as the delimiters, null splits on whitespace

Returns:

an array of parsed Strings, null if null String input

split
```
public static String[] split(String str,
                             String separatorChars,
                             int max)
```
Splits the provided text into an array with a maximum length, separators specified.

The separator is not included in the returned String array. Adjacent separators are treated as one separator.

A null input String returns null. A null separatorChars splits on whitespace.

If more than max delimited substrings are found, the last returned string includes all characters after the first max - 1 returned strings (including separator characters).
```
 StringUtils.split(null, *, *)            = null
 StringUtils.split("", *, *)              = []
 StringUtils.split("ab de fg", null, 0)   = ["ab", "cd", "ef"]
 StringUtils.split("ab   de fg", null, 0) = ["ab", "cd", "ef"]
 StringUtils.split("ab:cd:ef", ":", 0)    = ["ab", "cd", "ef"]
 StringUtils.split("ab:cd:ef", ":", 2)    = ["ab", "cd:ef"]
 
```
Parameters:

str - the String to parse, may be null

separatorChars - the characters used as the delimiters, null splits on whitespace

max - the maximum number of elements to include in the array. A zero or negative value implies no limit

Returns:

an array of parsed Strings, null if null String input

splitByWholeSeparator

public static String[] splitByWholeSeparator(String str,
                                             String separator)

Splits the provided text into an array, separator string specified.

The separator(s) will not be included in the returned String array. Adjacent separators are treated as one separator.

A null input String returns null. A null separator splits on whitespace.

 StringUtils.splitByWholeSeparator(null, *)               = null
 StringUtils.splitByWholeSeparator("", *)                 = []
 StringUtils.splitByWholeSeparator("ab de fg", null)      = ["ab", "de", "fg"]
 StringUtils.splitByWholeSeparator("ab   de fg", null)    = ["ab", "de", "fg"]
 StringUtils.splitByWholeSeparator("ab:cd:ef", ":")       = ["ab", "cd", "ef"]
 StringUtils.splitByWholeSeparator("ab-!-cd-!-ef", "-!-") = ["ab", "cd", "ef"]

Parameters:: str - the String to parse, may be null; separator - String containing the String to be used as a delimiter, null splits on whitespace
Returns:: an array of parsed Strings, null if null String was input

splitByWholeSeparator

public static String[] splitByWholeSeparator(String str,
                                             String separator,
                                             int max)

Splits the provided text into an array, separator string specified. Returns a maximum of max substrings.

The separator(s) will not be included in the returned String array. Adjacent separators are treated as one separator.

A null input String returns null. A null separator splits on whitespace.

 StringUtils.splitByWholeSeparator(null, *, *)               = null
 StringUtils.splitByWholeSeparator("", *, *)                 = []
 StringUtils.splitByWholeSeparator("ab de fg", null, 0)      = ["ab", "de", "fg"]
 StringUtils.splitByWholeSeparator("ab   de fg", null, 0)    = ["ab", "de", "fg"]
 StringUtils.splitByWholeSeparator("ab:cd:ef", ":", 2)       = ["ab", "cd:ef"]
 StringUtils.splitByWholeSeparator("ab-!-cd-!-ef", "-!-", 5) = ["ab", "cd", "ef"]
 StringUtils.splitByWholeSeparator("ab-!-cd-!-ef", "-!-", 2) = ["ab", "cd-!-ef"]

Parameters:: str - the String to parse, may be null; separator - String containing the String to be used as a delimiter, null splits on whitespace; max - the maximum number of elements to include in the returned array. A zero or negative value implies no limit.
Returns:: an array of parsed Strings, null if null String was input

splitByWholeSeparatorPreserveAllTokens

public static String[] splitByWholeSeparatorPreserveAllTokens(String str,
                                                              String separator)

Splits the provided text into an array, separator string specified.

The separator is not included in the returned String array. Adjacent separators are treated as separators for empty tokens. For more control over the split use the StrTokenizer class.

A null input String returns null. A null separator splits on whitespace.

 StringUtils.splitByWholeSeparatorPreserveAllTokens(null, *)               = null
 StringUtils.splitByWholeSeparatorPreserveAllTokens("", *)                 = []
 StringUtils.splitByWholeSeparatorPreserveAllTokens("ab de fg", null)      = ["ab", "de", "fg"]
 StringUtils.splitByWholeSeparatorPreserveAllTokens("ab   de fg", null)    = ["ab", "", "", "de", "fg"]
 StringUtils.splitByWholeSeparatorPreserveAllTokens("ab:cd:ef", ":")       = ["ab", "cd", "ef"]
 StringUtils.splitByWholeSeparatorPreserveAllTokens("ab-!-cd-!-ef", "-!-") = ["ab", "cd", "ef"]

Parameters:: str - the String to parse, may be null; separator - String containing the String to be used as a delimiter, null splits on whitespace
Returns:: an array of parsed Strings, null if null String was input
Since:: 2.4

splitByWholeSeparatorPreserveAllTokens

public static String[] splitByWholeSeparatorPreserveAllTokens(String str,
                                                              String separator,
                                                              int max)

Splits the provided text into an array, separator string specified. Returns a maximum of max substrings.

The separator is not included in the returned String array. Adjacent separators are treated as separators for empty tokens. For more control over the split use the StrTokenizer class.

A null input String returns null. A null separator splits on whitespace.

 StringUtils.splitByWholeSeparatorPreserveAllTokens(null, *, *)               = null
 StringUtils.splitByWholeSeparatorPreserveAllTokens("", *, *)                 = []
 StringUtils.splitByWholeSeparatorPreserveAllTokens("ab de fg", null, 0)      = ["ab", "de", "fg"]
 StringUtils.splitByWholeSeparatorPreserveAllTokens("ab   de fg", null, 0)    = ["ab", "", "", "de", "fg"]
 StringUtils.splitByWholeSeparatorPreserveAllTokens("ab:cd:ef", ":", 2)       = ["ab", "cd:ef"]
 StringUtils.splitByWholeSeparatorPreserveAllTokens("ab-!-cd-!-ef", "-!-", 5) = ["ab", "cd", "ef"]
 StringUtils.splitByWholeSeparatorPreserveAllTokens("ab-!-cd-!-ef", "-!-", 2) = ["ab", "cd-!-ef"]

Parameters:: str - the String to parse, may be null; separator - String containing the String to be used as a delimiter, null splits on whitespace; max - the maximum number of elements to include in the returned array. A zero or negative value implies no limit.
Returns:: an array of parsed Strings, null if null String was input
Since:: 2.4

splitPreserveAllTokens
```
public static String[] splitPreserveAllTokens(String str)
```
Splits the provided text into an array, using whitespace as the separator, preserving all tokens, including empty tokens created by adjacent separators. This is an alternative to using StringTokenizer. Whitespace is defined by Character.isWhitespace(char).

The separator is not included in the returned String array. Adjacent separators are treated as separators for empty tokens. For more control over the split use the StrTokenizer class.

A null input String returns null.
```
 StringUtils.splitPreserveAllTokens(null)       = null
 StringUtils.splitPreserveAllTokens("")         = []
 StringUtils.splitPreserveAllTokens("abc def")  = ["abc", "def"]
 StringUtils.splitPreserveAllTokens("abc  def") = ["abc", "", "def"]
 StringUtils.splitPreserveAllTokens(" abc ")    = ["", "abc", ""]
 
```
Parameters:

str - the String to parse, may be null

Returns:

an array of parsed Strings, null if null String input

Since:

2.1

splitPreserveAllTokens

public static String[] splitPreserveAllTokens(String str,
                                              char separatorChar)

Splits the provided text into an array, separator specified, preserving all tokens, including empty tokens created by adjacent separators. This is an alternative to using StringTokenizer.

The separator is not included in the returned String array. Adjacent separators are treated as separators for empty tokens. For more control over the split use the StrTokenizer class.

A null input String returns null.

 StringUtils.splitPreserveAllTokens(null, *)         = null
 StringUtils.splitPreserveAllTokens("", *)           = []
 StringUtils.splitPreserveAllTokens("a.b.c", '.')    = ["a", "b", "c"]
 StringUtils.splitPreserveAllTokens("a..b.c", '.')   = ["a", "", "b", "c"]
 StringUtils.splitPreserveAllTokens("a:b:c", '.')    = ["a:b:c"]
 StringUtils.splitPreserveAllTokens("a\tb\nc", null) = ["a", "b", "c"]
 StringUtils.splitPreserveAllTokens("a b c", ' ')    = ["a", "b", "c"]
 StringUtils.splitPreserveAllTokens("a b c ", ' ')   = ["a", "b", "c", ""]
 StringUtils.splitPreserveAllTokens("a b c  ", ' ')   = ["a", "b", "c", "", ""]
 StringUtils.splitPreserveAllTokens(" a b c", ' ')   = ["", a", "b", "c"]
 StringUtils.splitPreserveAllTokens("  a b c", ' ')  = ["", "", a", "b", "c"]
 StringUtils.splitPreserveAllTokens(" a b c ", ' ')  = ["", a", "b", "c", ""]

Parameters:: str - the String to parse, may be null; separatorChar - the character used as the delimiter, null splits on whitespace
Returns:: an array of parsed Strings, null if null String input
Since:: 2.1

splitPreserveAllTokens

public static String[] splitPreserveAllTokens(String str,
                                              String separatorChars)

Splits the provided text into an array, separators specified, preserving all tokens, including empty tokens created by adjacent separators. This is an alternative to using StringTokenizer.

The separator is not included in the returned String array. Adjacent separators are treated as separators for empty tokens. For more control over the split use the StrTokenizer class.

A null input String returns null. A null separatorChars splits on whitespace.

 StringUtils.splitPreserveAllTokens(null, *)           = null
 StringUtils.splitPreserveAllTokens("", *)             = []
 StringUtils.splitPreserveAllTokens("abc def", null)   = ["abc", "def"]
 StringUtils.splitPreserveAllTokens("abc def", " ")    = ["abc", "def"]
 StringUtils.splitPreserveAllTokens("abc  def", " ")   = ["abc", "", def"]
 StringUtils.splitPreserveAllTokens("ab:cd:ef", ":")   = ["ab", "cd", "ef"]
 StringUtils.splitPreserveAllTokens("ab:cd:ef:", ":")  = ["ab", "cd", "ef", ""]
 StringUtils.splitPreserveAllTokens("ab:cd:ef::", ":") = ["ab", "cd", "ef", "", ""]
 StringUtils.splitPreserveAllTokens("ab::cd:ef", ":")  = ["ab", "", cd", "ef"]
 StringUtils.splitPreserveAllTokens(":cd:ef", ":")     = ["", cd", "ef"]
 StringUtils.splitPreserveAllTokens("::cd:ef", ":")    = ["", "", cd", "ef"]
 StringUtils.splitPreserveAllTokens(":cd:ef:", ":")    = ["", cd", "ef", ""]

Parameters:: str - the String to parse, may be null; separatorChars - the characters used as the delimiters, null splits on whitespace
Returns:: an array of parsed Strings, null if null String input
Since:: 2.1

splitPreserveAllTokens

public static String[] splitPreserveAllTokens(String str,
                                              String separatorChars,
                                              int max)

Splits the provided text into an array with a maximum length, separators specified, preserving all tokens, including empty tokens created by adjacent separators.

The separator is not included in the returned String array. Adjacent separators are treated as separators for empty tokens. Adjacent separators are treated as one separator.

A null input String returns null. A null separatorChars splits on whitespace.

If more than max delimited substrings are found, the last returned string includes all characters after the first max - 1 returned strings (including separator characters).

 StringUtils.splitPreserveAllTokens(null, *, *)            = null
 StringUtils.splitPreserveAllTokens("", *, *)              = []
 StringUtils.splitPreserveAllTokens("ab de fg", null, 0)   = ["ab", "cd", "ef"]
 StringUtils.splitPreserveAllTokens("ab   de fg", null, 0) = ["ab", "cd", "ef"]
 StringUtils.splitPreserveAllTokens("ab:cd:ef", ":", 0)    = ["ab", "cd", "ef"]
 StringUtils.splitPreserveAllTokens("ab:cd:ef", ":", 2)    = ["ab", "cd:ef"]
 StringUtils.splitPreserveAllTokens("ab   de fg", null, 2) = ["ab", "  de fg"]
 StringUtils.splitPreserveAllTokens("ab   de fg", null, 3) = ["ab", "", " de fg"]
 StringUtils.splitPreserveAllTokens("ab   de fg", null, 4) = ["ab", "", "", "de fg"]

Parameters:: str - the String to parse, may be null; separatorChars - the characters used as the delimiters, null splits on whitespace; max - the maximum number of elements to include in the array. A zero or negative value implies no limit
Returns:: an array of parsed Strings, null if null String input
Since:: 2.1

splitByCharacterType

public static String[] splitByCharacterType(String str)

Splits a String by Character type as returned by java.lang.Character.getType(char). Groups of contiguous characters of the same type are returned as complete tokens.

 StringUtils.splitByCharacterType(null)         = null
 StringUtils.splitByCharacterType("")           = []
 StringUtils.splitByCharacterType("ab de fg")   = ["ab", " ", "de", " ", "fg"]
 StringUtils.splitByCharacterType("ab   de fg") = ["ab", "   ", "de", " ", "fg"]
 StringUtils.splitByCharacterType("ab:cd:ef")   = ["ab", ":", "cd", ":", "ef"]
 StringUtils.splitByCharacterType("number5")    = ["number", "5"]
 StringUtils.splitByCharacterType("fooBar")     = ["foo", "B", "ar"]
 StringUtils.splitByCharacterType("foo200Bar")  = ["foo", "200", "B", "ar"]
 StringUtils.splitByCharacterType("ASFRules")   = ["ASFR", "ules"]

Parameters:: str - the String to split, may be null
Returns:: an array of parsed Strings, null if null String input
Since:: 2.4

splitByCharacterTypeCamelCase

public static String[] splitByCharacterTypeCamelCase(String str)

Splits a String by Character type as returned by java.lang.Character.getType(char). Groups of contiguous characters of the same type are returned as complete tokens, with the following exception: the character of type Character.UPPERCASE_LETTER, if any, immediately preceding a token of type Character.LOWERCASE_LETTER will belong to the following token rather than to the preceding, if any, Character.UPPERCASE_LETTER token.

 StringUtils.splitByCharacterTypeCamelCase(null)         = null
 StringUtils.splitByCharacterTypeCamelCase("")           = []
 StringUtils.splitByCharacterTypeCamelCase("ab de fg")   = ["ab", " ", "de", " ", "fg"]
 StringUtils.splitByCharacterTypeCamelCase("ab   de fg") = ["ab", "   ", "de", " ", "fg"]
 StringUtils.splitByCharacterTypeCamelCase("ab:cd:ef")   = ["ab", ":", "cd", ":", "ef"]
 StringUtils.splitByCharacterTypeCamelCase("number5")    = ["number", "5"]
 StringUtils.splitByCharacterTypeCamelCase("fooBar")     = ["foo", "Bar"]
 StringUtils.splitByCharacterTypeCamelCase("foo200Bar")  = ["foo", "200", "Bar"]
 StringUtils.splitByCharacterTypeCamelCase("ASFRules")   = ["ASF", "Rules"]

Parameters:: str - the String to split, may be null
Returns:: an array of parsed Strings, null if null String input
Since:: 2.4

concatenate
```
public static String concatenate(Object[] array)
```
Deprecated. Use the better named join(Object[]) instead. Method will be removed in Commons Lang 3.0.
Joins the provided elements into a single String.

No separator is added to the joined String. Null objects or empty string elements are represented by empty strings.
```
 StringUtils.concatenate(null)            = null
 StringUtils.concatenate([])              = ""
 StringUtils.concatenate([null])          = ""
 StringUtils.concatenate(["a", "b", "c"]) = "abc"
 StringUtils.concatenate([null, "", "a"]) = "a"
 
```
Parameters:

array - the array of values to concatenate, may be null

Returns:

the concatenated String, null if null array input

join
```
public static String join(Object[] array)
```
Joins the elements of the provided array into a single String containing the provided list of elements.

No separator is added to the joined String. Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null)            = null
 StringUtils.join([])              = ""
 StringUtils.join([null])          = ""
 StringUtils.join(["a", "b", "c"]) = "abc"
 StringUtils.join([null, "", "a"]) = "a"
 
```
Parameters:

array - the array of values to join together, may be null

Returns:

the joined String, null if null array input

Since:

2.0

join
```
public static String join(Object[] array,
                          char separator)
```
Joins the elements of the provided array into a single String containing the provided list of elements.

No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *)               = null
 StringUtils.join([], *)                 = ""
 StringUtils.join([null], *)             = ""
 StringUtils.join(["a", "b", "c"], ';')  = "a;b;c"
 StringUtils.join(["a", "b", "c"], null) = "abc"
 StringUtils.join([null, "", "a"], ';')  = ";;a"
 
```
Parameters:

array - the array of values to join together, may be null

separator - the separator character to use

Returns:

the joined String, null if null array input

Since:

2.0

join
```
public static String join(Object[] array,
                          char separator,
                          int startIndex,
                          int endIndex)
```
Joins the elements of the provided array into a single String containing the provided list of elements.

No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *)               = null
 StringUtils.join([], *)                 = ""
 StringUtils.join([null], *)             = ""
 StringUtils.join(["a", "b", "c"], ';')  = "a;b;c"
 StringUtils.join(["a", "b", "c"], null) = "abc"
 StringUtils.join([null, "", "a"], ';')  = ";;a"
 
```
Parameters:

array - the array of values to join together, may be null

separator - the separator character to use

startIndex - the first index to start joining from. It is an error to pass in an end index past the end of the array

endIndex - the index to stop joining from (exclusive). It is an error to pass in an end index past the end of the array

Returns:

the joined String, null if null array input

Since:

2.0

join

public static String join(Object[] array,
                          String separator)

Joins the elements of the provided array into a single String containing the provided list of elements.

No delimiter is added before or after the list. A null separator is the same as an empty String (""). Null objects or empty strings within the array are represented by empty strings.

 StringUtils.join(null, *)                = null
 StringUtils.join([], *)                  = ""
 StringUtils.join([null], *)              = ""
 StringUtils.join(["a", "b", "c"], "--")  = "a--b--c"
 StringUtils.join(["a", "b", "c"], null)  = "abc"
 StringUtils.join(["a", "b", "c"], "")    = "abc"
 StringUtils.join([null, "", "a"], ',')   = ",,a"

Parameters:: array - the array of values to join together, may be null; separator - the separator character to use, null treated as ""
Returns:: the joined String, null if null array input

join
```
public static String join(Object[] array,
                          String separator,
                          int startIndex,
                          int endIndex)
```
Joins the elements of the provided array into a single String containing the provided list of elements.

No delimiter is added before or after the list. A null separator is the same as an empty String (""). Null objects or empty strings within the array are represented by empty strings.
```
 StringUtils.join(null, *)                = null
 StringUtils.join([], *)                  = ""
 StringUtils.join([null], *)              = ""
 StringUtils.join(["a", "b", "c"], "--")  = "a--b--c"
 StringUtils.join(["a", "b", "c"], null)  = "abc"
 StringUtils.join(["a", "b", "c"], "")    = "abc"
 StringUtils.join([null, "", "a"], ',')   = ",,a"
 
```
Parameters:

array - the array of values to join together, may be null

separator - the separator character to use, null treated as ""

startIndex - the first index to start joining from. It is an error to pass in an end index past the end of the array

endIndex - the index to stop joining from (exclusive). It is an error to pass in an end index past the end of the array

Returns:

the joined String, null if null array input

join
```
public static String join(Iterator<?> iterator,
                          char separator)
```
Joins the elements of the provided Iterator into a single String containing the provided elements.

No delimiter is added before or after the list. Null objects or empty strings within the iteration are represented by empty strings.

See the examples here: join(Object[],char).

Parameters:

iterator - the Iterator of values to join together, may be null

separator - the separator character to use

Returns:

the joined String, null if null iterator input

Since:

2.0

toString
```
public static String toString(Object obj)
```
Gets the toString of an Object returning an empty string ("") if null input.
```
 toString(null)         = ""
 toString("")           = ""
 toString("bat")        = "bat"
 toString(Boolean.TRUE) = "true"
 
```
Parameters:

obj - the Object to toString, may be null

Returns:

the passed in Object's toString, or nullStr if null input

Since:

2.0

See Also:

defaultString(String), String.valueOf(Object)

join
```
public static String join(Iterator<?> iterator,
                          String separator)
```
Joins the elements of the provided Iterator into a single String containing the provided elements.

No delimiter is added before or after the list. A null separator is the same as an empty String ("").

See the examples here: join(Object[],String).

Parameters:

iterator - the Iterator of values to join together, may be null

separator - the separator character to use, null treated as ""

Returns:

the joined String, null if null iterator input

join
```
public static String join(Collection<?> collection,
                          char separator)
```
Joins the elements of the provided Collection into a single String containing the provided elements.

No delimiter is added before or after the list. Null objects or empty strings within the iteration are represented by empty strings.

See the examples here: join(Object[],char).

Parameters:

collection - the Collection of values to join together, may be null

separator - the separator character to use

Returns:

the joined String, null if null iterator input

Since:

2.3

join
```
public static String join(Collection<?> collection,
                          String separator)
```
Joins the elements of the provided Collection into a single String containing the provided elements.

No delimiter is added before or after the list. A null separator is the same as an empty String ("").

See the examples here: join(Object[],String).

Parameters:

collection - the Collection of values to join together, may be null

separator - the separator character to use, null treated as ""

Returns:

the joined String, null if null iterator input

Since:

2.3

deleteWhitespace

public static String deleteWhitespace(String str)

Deletes all whitespaces from a String as defined by Character.isWhitespace(char).

 StringUtils.deleteWhitespace(null)         = null
 StringUtils.deleteWhitespace("")           = ""
 StringUtils.deleteWhitespace("abc")        = "abc"
 StringUtils.deleteWhitespace("   ab  c  ") = "abc"

Parameters:: str - the String to delete whitespace from, may be null
Returns:: the String without whitespaces, null if null String input

removeStart

public static String removeStart(String str,
                                 String remove)

Removes a substring only if it is at the begining of a source string, otherwise returns the source string.

A null source string will return null. An empty ("") source string will return the empty string. A null search string will return the source string.

 StringUtils.removeStart(null, *)      = null
 StringUtils.removeStart("", *)        = ""
 StringUtils.removeStart(*, null)      = *
 StringUtils.removeStart("www.domain.com", "www.")   = "domain.com"
 StringUtils.removeStart("domain.com", "www.")       = "domain.com"
 StringUtils.removeStart("www.domain.com", "domain") = "www.domain.com"
 StringUtils.removeStart("abc", "")    = "abc"

Parameters:: str - the source String to search, may be null; remove - the String to search for and remove, may be null
Returns:: the substring with the string removed if found, null if null String input
Since:: 2.1

removeStartIgnoreCase

public static String removeStartIgnoreCase(String str,
                                           String remove)

Case insensitive removal of a substring if it is at the begining of a source string, otherwise returns the source string.

A null source string will return null. An empty ("") source string will return the empty string. A null search string will return the source string.

 StringUtils.removeStartIgnoreCase(null, *)      = null
 StringUtils.removeStartIgnoreCase("", *)        = ""
 StringUtils.removeStartIgnoreCase(*, null)      = *
 StringUtils.removeStartIgnoreCase("www.domain.com", "www.")   = "domain.com"
 StringUtils.removeStartIgnoreCase("www.domain.com", "WWW.")   = "domain.com"
 StringUtils.removeStartIgnoreCase("domain.com", "www.")       = "domain.com"
 StringUtils.removeStartIgnoreCase("www.domain.com", "domain") = "www.domain.com"
 StringUtils.removeStartIgnoreCase("abc", "")    = "abc"

Parameters:: str - the source String to search, may be null; remove - the String to search for (case insensitive) and remove, may be null
Returns:: the substring with the string removed if found, null if null String input
Since:: 2.4

removeEnd

public static String removeEnd(String str,
                               String remove)

Removes a substring only if it is at the end of a source string, otherwise returns the source string.

A null source string will return null. An empty ("") source string will return the empty string. A null search string will return the source string.

 StringUtils.removeEnd(null, *)      = null
 StringUtils.removeEnd("", *)        = ""
 StringUtils.removeEnd(*, null)      = *
 StringUtils.removeEnd("www.domain.com", ".com.")  = "www.domain.com"
 StringUtils.removeEnd("www.domain.com", ".com")   = "www.domain"
 StringUtils.removeEnd("www.domain.com", "domain") = "www.domain.com"
 StringUtils.removeEnd("abc", "")    = "abc"

Parameters:: str - the source String to search, may be null; remove - the String to search for and remove, may be null
Returns:: the substring with the string removed if found, null if null String input
Since:: 2.1

removeEndIgnoreCase

public static String removeEndIgnoreCase(String str,
                                         String remove)

Case insensitive removal of a substring if it is at the end of a source string, otherwise returns the source string.

A null source string will return null. An empty ("") source string will return the empty string. A null search string will return the source string.

 StringUtils.removeEndIgnoreCase(null, *)      = null
 StringUtils.removeEndIgnoreCase("", *)        = ""
 StringUtils.removeEndIgnoreCase(*, null)      = *
 StringUtils.removeEndIgnoreCase("www.domain.com", ".com.")  = "www.domain.com"
 StringUtils.removeEndIgnoreCase("www.domain.com", ".com")   = "www.domain"
 StringUtils.removeEndIgnoreCase("www.domain.com", "domain") = "www.domain.com"
 StringUtils.removeEndIgnoreCase("abc", "")    = "abc"
 StringUtils.removeEndIgnoreCase("www.domain.com", ".COM") = "www.domain")
 StringUtils.removeEndIgnoreCase("www.domain.COM", ".com") = "www.domain")

Parameters:: str - the source String to search, may be null; remove - the String to search for (case insensitive) and remove, may be null
Returns:: the substring with the string removed if found, null if null String input
Since:: 2.4

remove
```
public static String remove(String str,
                            String remove)
```
Removes all occurrences of a substring from within the source string.

A null source string will return null. An empty ("") source string will return the empty string. A null remove string will return the source string. An empty ("") remove string will return the source string.
```
 StringUtils.remove(null, *)        = null
 StringUtils.remove("", *)          = ""
 StringUtils.remove(*, null)        = *
 StringUtils.remove(*, "")          = *
 StringUtils.remove("queued", "ue") = "qd"
 StringUtils.remove("queued", "zz") = "queued"
 
```
Parameters:

str - the source String to search, may be null

remove - the String to search for and remove, may be null

Returns:

the substring with the string removed if found, null if null String input

Since:

2.1

remove
```
public static String remove(String str,
                            char remove)
```
Removes all occurrences of a character from within the source string.

A null source string will return null. An empty ("") source string will return the empty string.
```
 StringUtils.remove(null, *)       = null
 StringUtils.remove("", *)         = ""
 StringUtils.remove("queued", 'u') = "qeed"
 StringUtils.remove("queued", 'z') = "queued"
 
```
Parameters:

str - the source String to search, may be null

remove - the char to search for and remove, may be null

Returns:

the substring with the char removed if found, null if null String input

Since:

2.1

replaceOnce

public static String replaceOnce(String text,
                                 String searchString,
                                 String replacement)

Replaces a String with another String inside a larger String, once.

A null reference passed to this method is a no-op.

 StringUtils.replaceOnce(null, *, *)        = null
 StringUtils.replaceOnce("", *, *)          = ""
 StringUtils.replaceOnce("any", null, *)    = "any"
 StringUtils.replaceOnce("any", *, null)    = "any"
 StringUtils.replaceOnce("any", "", *)      = "any"
 StringUtils.replaceOnce("aba", "a", null)  = "aba"
 StringUtils.replaceOnce("aba", "a", "")    = "ba"
 StringUtils.replaceOnce("aba", "a", "z")   = "zba"

Parameters:: text - text to search and replace in, may be null; searchString - the String to search for, may be null; replacement - the String to replace with, may be null
Returns:: the text with any replacements processed, null if null String input
See Also:: replace(String text, String searchString, String replacement, int max)

replace

public static String replace(String text,
                             String searchString,
                             String replacement)

Replaces all occurrences of a String within another String.

A null reference passed to this method is a no-op.

 StringUtils.replace(null, *, *)        = null
 StringUtils.replace("", *, *)          = ""
 StringUtils.replace("any", null, *)    = "any"
 StringUtils.replace("any", *, null)    = "any"
 StringUtils.replace("any", "", *)      = "any"
 StringUtils.replace("aba", "a", null)  = "aba"
 StringUtils.replace("aba", "a", "")    = "b"
 StringUtils.replace("aba", "a", "z")   = "zbz"

Parameters:: text - text to search and replace in, may be null; searchString - the String to search for, may be null; replacement - the String to replace it with, may be null
Returns:: the text with any replacements processed, null if null String input
See Also:: replace(String text, String searchString, String replacement, int max)

replace

public static String replace(String text,
                             String searchString,
                             String replacement,
                             int max)

Replaces a String with another String inside a larger String, for the first max values of the search String.

A null reference passed to this method is a no-op.

 StringUtils.replace(null, *, *, *)         = null
 StringUtils.replace("", *, *, *)           = ""
 StringUtils.replace("any", null, *, *)     = "any"
 StringUtils.replace("any", *, null, *)     = "any"
 StringUtils.replace("any", "", *, *)       = "any"
 StringUtils.replace("any", *, *, 0)        = "any"
 StringUtils.replace("abaa", "a", null, -1) = "abaa"
 StringUtils.replace("abaa", "a", "", -1)   = "b"
 StringUtils.replace("abaa", "a", "z", 0)   = "abaa"
 StringUtils.replace("abaa", "a", "z", 1)   = "zbaa"
 StringUtils.replace("abaa", "a", "z", 2)   = "zbza"
 StringUtils.replace("abaa", "a", "z", -1)  = "zbzz"

Parameters:: text - text to search and replace in, may be null; searchString - the String to search for, may be null; replacement - the String to replace it with, may be null; max - maximum number of values to replace, or -1 if no maximum
Returns:: the text with any replacements processed, null if null String input

replaceEach

public static String replaceEach(String text,
                                 String[] searchList,
                                 String[] replacementList)

Replaces all occurrences of Strings within another String.

A null reference passed to this method is a no-op, or if any "search string" or "string to replace" is null, that replace will be ignored. This will not repeat. For repeating replaces, call the overloaded method.

  StringUtils.replaceEach(null, *, *)        = null
  StringUtils.replaceEach("", *, *)          = ""
  StringUtils.replaceEach("aba", null, null) = "aba"
  StringUtils.replaceEach("aba", new String[0], null) = "aba"
  StringUtils.replaceEach("aba", null, new String[0]) = "aba"
  StringUtils.replaceEach("aba", new String[]{"a"}, null)  = "aba"
  StringUtils.replaceEach("aba", new String[]{"a"}, new String[]{""})  = "b"
  StringUtils.replaceEach("aba", new String[]{null}, new String[]{"a"})  = "aba"
  StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"w", "t"})  = "wcte"
  (example of how it does not repeat)
  StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"d", "t"})  = "dcte"

Parameters:: text - text to search and replace in, no-op if null; searchList - the Strings to search for, no-op if null; replacementList - the Strings to replace them with, no-op if null
Returns:: the text with any replacements processed, null if null String input
Throws:: IndexOutOfBoundsException - if the lengths of the arrays are not the same (null is ok, and/or size 0)
Since:: 2.4

replaceEachRepeatedly

public static String replaceEachRepeatedly(String text,
                                           String[] searchList,
                                           String[] replacementList)

Replaces all occurrences of Strings within another String.

  StringUtils.replaceEach(null, *, *, *) = null
  StringUtils.replaceEach("", *, *, *) = ""
  StringUtils.replaceEach("aba", null, null, *) = "aba"
  StringUtils.replaceEach("aba", new String[0], null, *) = "aba"
  StringUtils.replaceEach("aba", null, new String[0], *) = "aba"
  StringUtils.replaceEach("aba", new String[]{"a"}, null, *) = "aba"
  StringUtils.replaceEach("aba", new String[]{"a"}, new String[]{""}, *) = "b"
  StringUtils.replaceEach("aba", new String[]{null}, new String[]{"a"}, *) = "aba"
  StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"w", "t"}, *) = "wcte"
  (example of how it repeats)
  StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"d", "t"}, false) = "dcte"
  StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"d", "t"}, true) = "tcte"
  StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"d", "ab"}, true) = IllegalArgumentException
  StringUtils.replaceEach("abcde", new String[]{"ab", "d"}, new String[]{"d", "ab"}, false) = "dcabe"

Parameters:: text - text to search and replace in, no-op if null; searchList - the Strings to search for, no-op if null; replacementList - the Strings to replace them with, no-op if null
Returns:: the text with any replacements processed, null if null String input
Throws:: IllegalArgumentException - if the search is repeating and there is an endless loop due to outputs of one being inputs to another; IndexOutOfBoundsException - if the lengths of the arrays are not the same (null is ok, and/or size 0)
Since:: 2.4

replaceChars
```
public static String replaceChars(String str,
                                  char searchChar,
                                  char replaceChar)
```
Replaces all occurrences of a character in a String with another. This is a null-safe version of String.replace(char, char).

A null string input returns null. An empty ("") string input returns an empty string.
```
 StringUtils.replaceChars(null, *, *)        = null
 StringUtils.replaceChars("", *, *)          = ""
 StringUtils.replaceChars("abcba", 'b', 'y') = "aycya"
 StringUtils.replaceChars("abcba", 'z', 'y') = "abcba"
 
```
Parameters:

str - String to replace characters in, may be null

searchChar - the character to search for, may be null

replaceChar - the character to replace, may be null

Returns:

modified String, null if null string input

Since:

2.0

replaceChars
```
public static String replaceChars(String str,
                                  String searchChars,
                                  String replaceChars)
```
Replaces multiple characters in a String in one go. This method can also be used to delete characters.

For example:
replaceChars("hello", "ho", "jy") = jelly .

A null string input returns null. An empty ("") string input returns an empty string. A null or empty set of search characters returns the input string.

The length of the search characters should normally equal the length of the replace characters. If the search characters is longer, then the extra search characters are deleted. If the search characters is shorter, then the extra replace characters are ignored.
```
 StringUtils.replaceChars(null, *, *)           = null
 StringUtils.replaceChars("", *, *)             = ""
 StringUtils.replaceChars("abc", null, *)       = "abc"
 StringUtils.replaceChars("abc", "", *)         = "abc"
 StringUtils.replaceChars("abc", "b", null)     = "ac"
 StringUtils.replaceChars("abc", "b", "")       = "ac"
 StringUtils.replaceChars("abcba", "bc", "yz")  = "ayzya"
 StringUtils.replaceChars("abcba", "bc", "y")   = "ayya"
 StringUtils.replaceChars("abcba", "bc", "yzx") = "ayzya"
 
```
Parameters:

str - String to replace characters in, may be null

searchChars - a set of characters to search for, may be null

replaceChars - a set of characters to replace, may be null

Returns:

modified String, null if null string input

Since:

2.0

overlayString

public static String overlayString(String text,
                                   String overlay,
                                   int start,
                                   int end)

Deprecated. Use better named overlay(String, String, int, int) instead. Method will be removed in Commons Lang 3.0.

Overlays part of a String with another String.

 StringUtils.overlayString(null, *, *, *)           = NullPointerException
 StringUtils.overlayString(*, null, *, *)           = NullPointerException
 StringUtils.overlayString("", "abc", 0, 0)         = "abc"
 StringUtils.overlayString("abcdef", null, 2, 4)    = "abef"
 StringUtils.overlayString("abcdef", "", 2, 4)      = "abef"
 StringUtils.overlayString("abcdef", "zzzz", 2, 4)  = "abzzzzef"
 StringUtils.overlayString("abcdef", "zzzz", 4, 2)  = "abcdzzzzcdef"
 StringUtils.overlayString("abcdef", "zzzz", -1, 4) = IndexOutOfBoundsException
 StringUtils.overlayString("abcdef", "zzzz", 2, 8)  = IndexOutOfBoundsException

Parameters:: text - the String to do overlaying in, may be null; overlay - the String to overlay, may be null; start - the position to start overlaying at, must be valid; end - the position to stop overlaying before, must be valid
Returns:: overlayed String, null if null String input
Throws:: NullPointerException - if text or overlay is null; IndexOutOfBoundsException - if either position is invalid

overlay

public static String overlay(String str,
                             String overlay,
                             int start,
                             int end)

Overlays part of a String with another String.

A null string input returns null. A negative index is treated as zero. An index greater than the string length is treated as the string length. The start index is always the smaller of the two indices.

 StringUtils.overlay(null, *, *, *)            = null
 StringUtils.overlay("", "abc", 0, 0)          = "abc"
 StringUtils.overlay("abcdef", null, 2, 4)     = "abef"
 StringUtils.overlay("abcdef", "", 2, 4)       = "abef"
 StringUtils.overlay("abcdef", "", 4, 2)       = "abef"
 StringUtils.overlay("abcdef", "zzzz", 2, 4)   = "abzzzzef"
 StringUtils.overlay("abcdef", "zzzz", 4, 2)   = "abzzzzef"
 StringUtils.overlay("abcdef", "zzzz", -1, 4)  = "zzzzef"
 StringUtils.overlay("abcdef", "zzzz", 2, 8)   = "abzzzz"
 StringUtils.overlay("abcdef", "zzzz", -2, -3) = "zzzzabcdef"
 StringUtils.overlay("abcdef", "zzzz", 8, 10)  = "abcdefzzzz"

Parameters:: str - the String to do overlaying in, may be null; overlay - the String to overlay, may be null; start - the position to start overlaying at; end - the position to stop overlaying before
Returns:: overlayed String, null if null String input
Since:: 2.0

chomp

public static String chomp(String str)

Removes one newline from end of a String if it's there, otherwise leave it alone. A newline is "\n", "\r ", or "\r\n".

NOTE: This method changed in 2.0. It now more closely matches Perl chomp.

 StringUtils.chomp(null)          = null
 StringUtils.chomp("")            = ""
 StringUtils.chomp("abc \r")      = "abc "
 StringUtils.chomp("abc\n")       = "abc"
 StringUtils.chomp("abc\r\n")     = "abc"
 StringUtils.chomp("abc\r\n\r\n") = "abc\r\n"
 StringUtils.chomp("abc\n\r")     = "abc\n"
 StringUtils.chomp("abc\n\rabc")  = "abc\n\rabc"
 StringUtils.chomp("\r")          = ""
 StringUtils.chomp("\n")          = ""
 StringUtils.chomp("\r\n")        = ""

Parameters:: str - the String to chomp a newline from, may be null
Returns:: String without newline, null if null String input

chomp

public static String chomp(String str,
                           String separator)

Removes separator from the end of str if it's there, otherwise leave it alone.

NOTE: This method changed in version 2.0. It now more closely matches Perl chomp. For the previous behavior, use substringBeforeLast(String, String). This method uses String.endsWith(String).

 StringUtils.chomp(null, *)         = null
 StringUtils.chomp("", *)           = ""
 StringUtils.chomp("foobar", "bar") = "foo"
 StringUtils.chomp("foobar", "baz") = "foobar"
 StringUtils.chomp("foo", "foo")    = ""
 StringUtils.chomp("foo ", "foo")   = "foo "
 StringUtils.chomp(" foo", "foo")   = " "
 StringUtils.chomp("foo", "foooo")  = "foo"
 StringUtils.chomp("foo", "")       = "foo"
 StringUtils.chomp("foo", null)     = "foo"

Parameters:: str - the String to chomp from, may be null; separator - separator String, may be null
Returns:: String without trailing separator, null if null String input

chompLast
```
public static String chompLast(String str)
```
Deprecated. Use chomp(String) instead. Method will be removed in Commons Lang 3.0.

Remove any "\n" if and only if it is at the end of the supplied String.

Parameters:

str - the String to chomp from, must not be null

Returns:

String without chomped ending

Throws:

NullPointerException - if str is null

chompLast
```
public static String chompLast(String str,
                               String sep)
```
Deprecated. Use chomp(String,String) instead. Method will be removed in Commons Lang 3.0.

Remove a value if and only if the String ends with that value.

Parameters:

str - the String to chomp from, must not be null

sep - the String to chomp, must not be null

Returns:

String without chomped ending

Throws:

NullPointerException - if str or sep is null

getChomp
```
public static String getChomp(String str,
                              String sep)
```
Deprecated. Use substringAfterLast(String, String) instead (although this doesn't include the separator) Method will be removed in Commons Lang 3.0.

Remove everything and return the last value of a supplied String, and everything after it from a String.

Parameters:

str - the String to chomp from, must not be null

sep - the String to chomp, must not be null

Returns:

String chomped

Throws:

NullPointerException - if str or sep is null

prechomp
```
public static String prechomp(String str,
                              String sep)
```
Deprecated. Use substringAfter(String,String) instead. Method will be removed in Commons Lang 3.0.

Remove the first value of a supplied String, and everything before it from a String.

Parameters:

str - the String to chomp from, must not be null

sep - the String to chomp, must not be null

Returns:

String without chomped beginning

Throws:

NullPointerException - if str or sep is null

getPrechomp
```
public static String getPrechomp(String str,
                                 String sep)
```
Deprecated. Use substringBefore(String,String) instead (although this doesn't include the separator). Method will be removed in Commons Lang 3.0.

Remove and return everything before the first value of a supplied String from another String.

Parameters:

str - the String to chomp from, must not be null

sep - the String to chomp, must not be null

Returns:

String prechomped

Throws:

NullPointerException - if str or sep is null

chop

public static String chop(String str)

Remove the last character from a String.

If the String ends in \r\n, then remove both of them.

 StringUtils.chop(null)          = null
 StringUtils.chop("")            = ""
 StringUtils.chop("abc \r")      = "abc "
 StringUtils.chop("abc\n")       = "abc"
 StringUtils.chop("abc\r\n")     = "abc"
 StringUtils.chop("abc")         = "ab"
 StringUtils.chop("abc\nabc")    = "abc\nab"
 StringUtils.chop("a")           = ""
 StringUtils.chop("\r")          = ""
 StringUtils.chop("\n")          = ""
 StringUtils.chop("\r\n")        = ""

Parameters:: str - the String to chop last character from, may be null
Returns:: String without last character, null if null String input

chopNewline
```
public static String chopNewline(String str)
```
Deprecated. Use chomp(String) instead. Method will be removed in Commons Lang 3.0.

Removes \n from end of a String if it's there. If a \r precedes it, then remove that too.

Parameters:

str - the String to chop a newline from, must not be null

Returns:

String without newline

Throws:

NullPointerException - if str is null

repeat

public static String repeat(String str,
                            int repeat)

Repeat a String repeat times to form a new String.

 StringUtils.repeat(null, 2) = null
 StringUtils.repeat("", 0)   = ""
 StringUtils.repeat("", 2)   = ""
 StringUtils.repeat("a", 3)  = "aaa"
 StringUtils.repeat("ab", 2) = "abab"
 StringUtils.repeat("a", -2) = ""

Parameters:: str - the String to repeat, may be null; repeat - number of times to repeat str, negative treated as zero
Returns:: a new String consisting of the original String repeated, null if null String input

repeat

public static String repeat(String str,
                            String separator,
                            int repeat)

Repeat a String repeat times to form a new String, with a String separator injected each time.

 StringUtils.repeat(null, null, 2) = null
 StringUtils.repeat(null, "x", 2)  = null
 StringUtils.repeat("", null, 0)   = ""
 StringUtils.repeat("", "", 2)     = ""
 StringUtils.repeat("", "x", 3)    = "xxx"
 StringUtils.repeat("?", ", ", 3)  = "?, ?, ?"

Parameters:: str - the String to repeat, may be null; separator - the String to inject, may be null; repeat - number of times to repeat str, negative treated as zero
Returns:: a new String consisting of the original String repeated, null if null String input
Since:: 2.5

rightPad

public static String rightPad(String str,
                              int size)

Right pad a String with spaces (' ').

The String is padded to the size of size.

 StringUtils.rightPad(null, *)   = null
 StringUtils.rightPad("", 3)     = "   "
 StringUtils.rightPad("bat", 3)  = "bat"
 StringUtils.rightPad("bat", 5)  = "bat  "
 StringUtils.rightPad("bat", 1)  = "bat"
 StringUtils.rightPad("bat", -1) = "bat"

Parameters:: str - the String to pad out, may be null; size - the size to pad to
Returns:: right padded String or original String if no padding is necessary, null if null String input

rightPad

public static String rightPad(String str,
                              int size,
                              char padChar)

Right pad a String with a specified character.

The String is padded to the size of size.

 StringUtils.rightPad(null, *, *)     = null
 StringUtils.rightPad("", 3, 'z')     = "zzz"
 StringUtils.rightPad("bat", 3, 'z')  = "bat"
 StringUtils.rightPad("bat", 5, 'z')  = "batzz"
 StringUtils.rightPad("bat", 1, 'z')  = "bat"
 StringUtils.rightPad("bat", -1, 'z') = "bat"

Parameters:: str - the String to pad out, may be null; size - the size to pad to; padChar - the character to pad with
Returns:: right padded String or original String if no padding is necessary, null if null String input
Since:: 2.0

rightPad

public static String rightPad(String str,
                              int size,
                              String padStr)

Right pad a String with a specified String.

The String is padded to the size of size.

 StringUtils.rightPad(null, *, *)      = null
 StringUtils.rightPad("", 3, "z")      = "zzz"
 StringUtils.rightPad("bat", 3, "yz")  = "bat"
 StringUtils.rightPad("bat", 5, "yz")  = "batyz"
 StringUtils.rightPad("bat", 8, "yz")  = "batyzyzy"
 StringUtils.rightPad("bat", 1, "yz")  = "bat"
 StringUtils.rightPad("bat", -1, "yz") = "bat"
 StringUtils.rightPad("bat", 5, null)  = "bat  "
 StringUtils.rightPad("bat", 5, "")    = "bat  "

Parameters:: str - the String to pad out, may be null; size - the size to pad to; padStr - the String to pad with, null or empty treated as single space
Returns:: right padded String or original String if no padding is necessary, null if null String input

leftPad

public static String leftPad(String str,
                             int size)

Left pad a String with spaces (' ').

The String is padded to the size of size.

 StringUtils.leftPad(null, *)   = null
 StringUtils.leftPad("", 3)     = "   "
 StringUtils.leftPad("bat", 3)  = "bat"
 StringUtils.leftPad("bat", 5)  = "  bat"
 StringUtils.leftPad("bat", 1)  = "bat"
 StringUtils.leftPad("bat", -1) = "bat"

Parameters:: str - the String to pad out, may be null; size - the size to pad to
Returns:: left padded String or original String if no padding is necessary, null if null String input

leftPad

public static String leftPad(String str,
                             int size,
                             char padChar)

Left pad a String with a specified character.

Pad to a size of size.

 StringUtils.leftPad(null, *, *)     = null
 StringUtils.leftPad("", 3, 'z')     = "zzz"
 StringUtils.leftPad("bat", 3, 'z')  = "bat"
 StringUtils.leftPad("bat", 5, 'z')  = "zzbat"
 StringUtils.leftPad("bat", 1, 'z')  = "bat"
 StringUtils.leftPad("bat", -1, 'z') = "bat"

Parameters:: str - the String to pad out, may be null; size - the size to pad to; padChar - the character to pad with
Returns:: left padded String or original String if no padding is necessary, null if null String input
Since:: 2.0

leftPad

public static String leftPad(String str,
                             int size,
                             String padStr)

Left pad a String with a specified String.

Pad to a size of size.

 StringUtils.leftPad(null, *, *)      = null
 StringUtils.leftPad("", 3, "z")      = "zzz"
 StringUtils.leftPad("bat", 3, "yz")  = "bat"
 StringUtils.leftPad("bat", 5, "yz")  = "yzbat"
 StringUtils.leftPad("bat", 8, "yz")  = "yzyzybat"
 StringUtils.leftPad("bat", 1, "yz")  = "bat"
 StringUtils.leftPad("bat", -1, "yz") = "bat"
 StringUtils.leftPad("bat", 5, null)  = "  bat"
 StringUtils.leftPad("bat", 5, "")    = "  bat"

Parameters:: str - the String to pad out, may be null; size - the size to pad to; padStr - the String to pad with, null or empty treated as single space
Returns:: left padded String or original String if no padding is necessary, null if null String input

length
```
public static int length(String str)
```
Gets a String's length or 0 if the String is null.

Parameters:

str - a String or null

Returns:

String length or 0 if the String is null.

Since:

2.4

center
```
public static String center(String str,
                            int size)
```
Centers a String in a larger String of size size using the space character (' ').
If the size is less than the String length, the String is returned. A null String returns null. A negative size is treated as zero.

Equivalent to center(str, size, " ").
```
 StringUtils.center(null, *)   = null
 StringUtils.center("", 4)     = "    "
 StringUtils.center("ab", -1)  = "ab"
 StringUtils.center("ab", 4)   = " ab "
 StringUtils.center("abcd", 2) = "abcd"
 StringUtils.center("a", 4)    = " a  "
 
```
Parameters:

str - the String to center, may be null

size - the int size of new String, negative treated as zero

Returns:

centered String, null if null String input

center
```
public static String center(String str,
                            int size,
                            char padChar)
```
Centers a String in a larger String of size size. Uses a supplied character as the value to pad the String with.

If the size is less than the String length, the String is returned. A null String returns null. A negative size is treated as zero.
```
 StringUtils.center(null, *, *)     = null
 StringUtils.center("", 4, ' ')     = "    "
 StringUtils.center("ab", -1, ' ')  = "ab"
 StringUtils.center("ab", 4, ' ')   = " ab"
 StringUtils.center("abcd", 2, ' ') = "abcd"
 StringUtils.center("a", 4, ' ')    = " a  "
 StringUtils.center("a", 4, 'y')    = "yayy"
 
```
Parameters:

str - the String to center, may be null

size - the int size of new String, negative treated as zero

padChar - the character to pad the new String with

Returns:

centered String, null if null String input

Since:

2.0

center

public static String center(String str,
                            int size,
                            String padStr)

Centers a String in a larger String of size size. Uses a supplied String as the value to pad the String with.

If the size is less than the String length, the String is returned. A null String returns null. A negative size is treated as zero.

 StringUtils.center(null, *, *)     = null
 StringUtils.center("", 4, " ")     = "    "
 StringUtils.center("ab", -1, " ")  = "ab"
 StringUtils.center("ab", 4, " ")   = " ab"
 StringUtils.center("abcd", 2, " ") = "abcd"
 StringUtils.center("a", 4, " ")    = " a  "
 StringUtils.center("a", 4, "yz")   = "yayz"
 StringUtils.center("abc", 7, null) = "  abc  "
 StringUtils.center("abc", 7, "")   = "  abc  "

Parameters:: str - the String to center, may be null; size - the int size of new String, negative treated as zero; padStr - the String to pad the new String with, must not be null or empty
Returns:: centered String, null if null String input
Throws:: IllegalArgumentException - if padStr is null or empty

upperCase
```
public static String upperCase(String str)
```
Converts a String to upper case as per String.toUpperCase().

A null input String returns null.
```
 StringUtils.upperCase(null)  = null
 StringUtils.upperCase("")    = ""
 StringUtils.upperCase("aBc") = "ABC"
 
```
Note: As described in the documentation for String.toUpperCase(), the result of this method is affected by the current locale. For platform-independent case transformations, the method lowerCase(String, Locale) should be used with a specific locale (e.g. Locale.ENGLISH).
Parameters:

str - the String to upper case, may be null

Returns:

the upper cased String, null if null String input

upperCase
```
public static String upperCase(String str,
                               Locale locale)
```
Converts a String to upper case as per String.toUpperCase(Locale) .

A null input String returns null.
```
 StringUtils.upperCase(null, Locale.ENGLISH)  = null
 StringUtils.upperCase("", Locale.ENGLISH)    = ""
 StringUtils.upperCase("aBc", Locale.ENGLISH) = "ABC"
 
```
Parameters:

str - the String to upper case, may be null

locale - the locale that defines the case transformation rules, must not be null

Returns:

the upper cased String, null if null String input

Since:

2.5

lowerCase
```
public static String lowerCase(String str)
```
Converts a String to lower case as per String.toLowerCase().

A null input String returns null.
```
 StringUtils.lowerCase(null)  = null
 StringUtils.lowerCase("")    = ""
 StringUtils.lowerCase("aBc") = "abc"
 
```
Note: As described in the documentation for String.toLowerCase(), the result of this method is affected by the current locale. For platform-independent case transformations, the method lowerCase(String, Locale) should be used with a specific locale (e.g. Locale.ENGLISH).
Parameters:

str - the String to lower case, may be null

Returns:

the lower cased String, null if null String input

lowerCase
```
public static String lowerCase(String str,
                               Locale locale)
```
Converts a String to lower case as per String.toLowerCase(Locale) .

A null input String returns null.
```
 StringUtils.lowerCase(null, Locale.ENGLISH)  = null
 StringUtils.lowerCase("", Locale.ENGLISH)    = ""
 StringUtils.lowerCase("aBc", Locale.ENGLISH) = "abc"
 
```
Parameters:

str - the String to lower case, may be null

locale - the locale that defines the case transformation rules, must not be null

Returns:

the lower cased String, null if null String input

Since:

2.5

capitalize
```
public static String capitalize(String str)
```
Capitalizes a String changing the first letter to title case as per Character.toTitleCase(char). No other letters are changed.

For a word based algorithm, see capitalize(String). A null input String returns null.
```
 StringUtils.capitalize(null)  = null
 StringUtils.capitalize("")    = ""
 StringUtils.capitalize("cat") = "Cat"
 StringUtils.capitalize("cAt") = "CAt"
 
```
Parameters:

str - the String to capitalize, may be null

Returns:

the capitalized String, null if null String input

Since:

2.0

See Also:

capitalize(String), uncapitalize(String)

capitalise
```
public static String capitalise(String str)
```
Deprecated. Use the standardly named capitalize(String). Method will be removed in Commons Lang 3.0.

Capitalizes a String changing the first letter to title case as per Character.toTitleCase(char). No other letters are changed.

Parameters:

str - the String to capitalize, may be null

Returns:

the capitalized String, null if null String input

uncapitalize
```
public static String uncapitalize(String str)
```
Uncapitalizes a String changing the first letter to title case as per Character.toLowerCase(char). No other letters are changed.

For a word based algorithm, see uncapitalize(String). A null input String returns null.
```
 StringUtils.uncapitalize(null)  = null
 StringUtils.uncapitalize("")    = ""
 StringUtils.uncapitalize("Cat") = "cat"
 StringUtils.uncapitalize("CAT") = "cAT"
 
```
Parameters:

str - the String to uncapitalize, may be null

Returns:

the uncapitalized String, null if null String input

Since:

2.0

See Also:

uncapitalize(String), capitalize(String)

uncapitalise
```
public static String uncapitalise(String str)
```
Deprecated. Use the standardly named uncapitalize(String). Method will be removed in Commons Lang 3.0.

Uncapitalizes a String changing the first letter to title case as per Character.toLowerCase(char). No other letters are changed.

Parameters:

str - the String to uncapitalize, may be null

Returns:

the uncapitalized String, null if null String input

swapCase
```
public static String swapCase(String str)
```
Swaps the case of a String changing upper and title case to lower case, and lower case to upper case.
- Upper case character converts to Lower case
- Title case character converts to Lower case
- Lower case character converts to Upper case
For a word based algorithm, see swapCase(String). A null input String returns null.
```
 StringUtils.swapCase(null)                 = null
 StringUtils.swapCase("")                   = ""
 StringUtils.swapCase("The dog has a BONE") = "tHE DOG HAS A bone"
 
```
NOTE: This method changed in Lang version 2.0. It no longer performs a word based algorithm. If you only use ASCII, you will notice no change. That functionality is available in StringUtils.
Parameters:

str - the String to swap case, may be null

Returns:

the changed String, null if null String input

capitaliseAllWords
```
public static String capitaliseAllWords(String str)
```
Deprecated. Use the relocated capitalize(String). Method will be removed in Commons Lang 3.0.

Capitalizes all the whitespace separated words in a String. Only the first letter of each word is changed.

Whitespace is defined by Character.isWhitespace(char). A null input String returns null.

Parameters:

str - the String to capitalize, may be null

Returns:

capitalized String, null if null String input

capitalize
```
public static String capitalize(String str,
                                char[] delimiters)
```
Capitalizes all the delimiter separated words in a String. Only the first letter of each word is changed. To convert the rest of each word to lowercase at the same time.
The delimiters represent a set of characters understood to separate words. The first string character and the first non-delimiter character after a delimiter will be capitalized.

A null input String returns null. Capitalization uses the unicode title case, normally equivalent to upper case.
```
 StringUtils.capitalize(null, *)            = null
 StringUtils.capitalize("", *)              = ""
 StringUtils.capitalize(*, new char[0])     = *
 StringUtils.capitalize("i am fine", null)  = "I Am Fine"
 StringUtils.capitalize("i aM.fine", {'.'}) = "I aM.Fine"
 
```
Parameters:

str - the String to capitalize, may be null

delimiters - set of characters to determine capitalization, null means whitespace

Returns:

capitalized String, null if null String input

Since:

2.1

See Also:

uncapitalize(String)

countMatches

public static int countMatches(String str,
                               String sub)

Counts how many times the substring appears in the larger String.

A null or empty ("") String input returns 0.

 StringUtils.countMatches(null, *)       = 0
 StringUtils.countMatches("", *)         = 0
 StringUtils.countMatches("abba", null)  = 0
 StringUtils.countMatches("abba", "")    = 0
 StringUtils.countMatches("abba", "a")   = 2
 StringUtils.countMatches("abba", "ab")  = 1
 StringUtils.countMatches("abba", "xxx") = 0

Parameters:: str - the String to check, may be null; sub - the substring to count, may be null
Returns:: the number of occurrences, 0 if either String is null

isAlpha

public static boolean isAlpha(String str)

Checks if the String contains only unicode letters.

null will return false. An empty String (length()=0) will return true.

 StringUtils.isAlpha(null)   = false
 StringUtils.isAlpha("")     = true
 StringUtils.isAlpha("  ")   = false
 StringUtils.isAlpha("abc")  = true
 StringUtils.isAlpha("ab2c") = false
 StringUtils.isAlpha("ab-c") = false

Parameters:: str - the String to check, may be null
Returns:: true if only contains letters, and is non-null

isAlphaSpace

public static boolean isAlphaSpace(String str)

Checks if the String contains only unicode letters and space (' ').

null will return false An empty String (length()=0) will return true.

 StringUtils.isAlphaSpace(null)   = false
 StringUtils.isAlphaSpace("")     = true
 StringUtils.isAlphaSpace("  ")   = true
 StringUtils.isAlphaSpace("abc")  = true
 StringUtils.isAlphaSpace("ab c") = true
 StringUtils.isAlphaSpace("ab2c") = false
 StringUtils.isAlphaSpace("ab-c") = false

Parameters:: str - the String to check, may be null
Returns:: true if only contains letters and space, and is non-null

isAlphanumeric

public static boolean isAlphanumeric(String str)

Checks if the String contains only unicode letters or digits.

null will return false. An empty String (length()=0) will return true.

 StringUtils.isAlphanumeric(null)   = false
 StringUtils.isAlphanumeric("")     = true
 StringUtils.isAlphanumeric("  ")   = false
 StringUtils.isAlphanumeric("abc")  = true
 StringUtils.isAlphanumeric("ab c") = false
 StringUtils.isAlphanumeric("ab2c") = true
 StringUtils.isAlphanumeric("ab-c") = false

Parameters:: str - the String to check, may be null
Returns:: true if only contains letters or digits, and is non-null

isAlphanumericSpace

public static boolean isAlphanumericSpace(String str)

Checks if the String contains only unicode letters, digits or space ( ' ').

null will return false. An empty String (length()=0) will return true.

 StringUtils.isAlphanumeric(null)   = false
 StringUtils.isAlphanumeric("")     = true
 StringUtils.isAlphanumeric("  ")   = true
 StringUtils.isAlphanumeric("abc")  = true
 StringUtils.isAlphanumeric("ab c") = true
 StringUtils.isAlphanumeric("ab2c") = true
 StringUtils.isAlphanumeric("ab-c") = false

Parameters:: str - the String to check, may be null
Returns:: true if only contains letters, digits or space, and is non-null

isAsciiPrintable

public static boolean isAsciiPrintable(String str)

Checks if the string contains only ASCII printable characters.

null will return false. An empty String (length()=0) will return true.

 StringUtils.isAsciiPrintable(null)     = false
 StringUtils.isAsciiPrintable("")       = true
 StringUtils.isAsciiPrintable(" ")      = true
 StringUtils.isAsciiPrintable("Ceki")   = true
 StringUtils.isAsciiPrintable("ab2c")   = true
 StringUtils.isAsciiPrintable("!ab-c~") = true
 StringUtils.isAsciiPrintable(" ") = true
 StringUtils.isAsciiPrintable("!") = true
 StringUtils.isAsciiPrintable("~") = true
 StringUtils.isAsciiPrintable("") = false
 StringUtils.isAsciiPrintable("Ceki Gülcü") = false

Parameters:: str - the string to check, may be null
Returns:: true if every character is in the range 32 thru 126
Since:: 2.1

isAsciiPrintable

public static boolean isAsciiPrintable(char ch)

Checks whether the character is ASCII 7 bit printable.

   StringUtils.isAsciiPrintable('a')  = true
   StringUtils.isAsciiPrintable('A')  = true
   StringUtils.isAsciiPrintable('3')  = true
   StringUtils.isAsciiPrintable('-')  = true
   StringUtils.isAsciiPrintable('\n') = false
   StringUtils.isAsciiPrintable('©') = false

Parameters:: ch - the character to check
Returns:: true if between 32 and 126 inclusive

isNumeric

public static boolean isNumeric(String str)

Checks if the String contains only unicode digits. A decimal point is not a unicode digit and returns false.

null will return false. An empty String (length()=0) will return true.

 StringUtils.isNumeric(null)   = false
 StringUtils.isNumeric("")     = true
 StringUtils.isNumeric("  ")   = false
 StringUtils.isNumeric("123")  = true
 StringUtils.isNumeric("12 3") = false
 StringUtils.isNumeric("ab2c") = false
 StringUtils.isNumeric("12-3") = false
 StringUtils.isNumeric("12.3") = false

Parameters:: str - the String to check, may be null
Returns:: true if only contains digits, and is non-null

isNumericSpace

public static boolean isNumericSpace(String str)

Checks if the String contains only unicode digits or space ( ' '). A decimal point is not a unicode digit and returns false.

null will return false. An empty String (length()=0) will return true.

 StringUtils.isNumeric(null)   = false
 StringUtils.isNumeric("")     = true
 StringUtils.isNumeric("  ")   = true
 StringUtils.isNumeric("123")  = true
 StringUtils.isNumeric("12 3") = true
 StringUtils.isNumeric("ab2c") = false
 StringUtils.isNumeric("12-3") = false
 StringUtils.isNumeric("12.3") = false

Parameters:: str - the String to check, may be null
Returns:: true if only contains digits or space, and is non-null

isWhitespace

public static boolean isWhitespace(String str)

Checks if the String contains only whitespace.

null will return false. An empty String (length()=0) will return true.

 StringUtils.isWhitespace(null)   = false
 StringUtils.isWhitespace("")     = true
 StringUtils.isWhitespace("  ")   = true
 StringUtils.isWhitespace("abc")  = false
 StringUtils.isWhitespace("ab2c") = false
 StringUtils.isWhitespace("ab-c") = false

Parameters:: str - the String to check, may be null
Returns:: true if only contains whitespace, and is non-null
Since:: 2.0

isAllLowerCase

public static boolean isAllLowerCase(String str)

Checks if the String contains only lowercase characters.

null will return false. An empty String (length()=0) will return false.

 StringUtils.isAllLowerCase(null)   = false
 StringUtils.isAllLowerCase("")     = false
 StringUtils.isAllLowerCase("  ")   = false
 StringUtils.isAllLowerCase("abc")  = true
 StringUtils.isAllLowerCase("abC") = false

Parameters:: str - the String to check, may be null
Returns:: true if only contains lowercase characters, and is non-null
Since:: 2.5

isAllUpperCase

public static boolean isAllUpperCase(String str)

Checks if the String contains only uppercase characters.

null will return false. An empty String (length()=0) will return false.

 StringUtils.isAllUpperCase(null)   = false
 StringUtils.isAllUpperCase("")     = false
 StringUtils.isAllUpperCase("  ")   = false
 StringUtils.isAllUpperCase("ABC")  = true
 StringUtils.isAllUpperCase("aBC") = false

Parameters:: str - the String to check, may be null
Returns:: true if only contains uppercase characters, and is non-null
Since:: 2.5

defaultString
```
public static String defaultString(String str)
```
Returns either the passed in String, or if the String is null, an empty String ("").
```
 StringUtils.defaultString(null)  = ""
 StringUtils.defaultString("")    = ""
 StringUtils.defaultString("bat") = "bat"
 
```
Parameters:

str - the String to check, may be null

Returns:

the passed in String, or the empty String if it was null

See Also:

toString(Object), String.valueOf(Object)

defaultString
```
public static String defaultString(String str,
                                   String defaultStr)
```
Returns either the passed in String, or if the String is null, the value of defaultStr.
```
 StringUtils.defaultString(null, "NULL")  = "NULL"
 StringUtils.defaultString("", "NULL")    = ""
 StringUtils.defaultString("bat", "NULL") = "bat"
 
```
Parameters:

str - the String to check, may be null

defaultStr - the default String to return if the input is null , may be null

Returns:

the passed in String, or the default if it was null

See Also:

String.valueOf(Object)

defaultIfBlank

public static String defaultIfBlank(String str,
                                    String defaultStr)

Returns either the passed in String, or if the String is whitespace, empty ("") or null, the value of defaultStr.

 StringUtils.defaultIfBlank(null, "NULL")  = "NULL"
 StringUtils.defaultIfBlank("", "NULL")    = "NULL"
 StringUtils.defaultIfBlank(" ", "NULL")   = "NULL"
 StringUtils.defaultIfBlank("bat", "NULL") = "bat"
 StringUtils.defaultIfBlank("", null)      = null

Parameters:: str - the String to check, may be null; defaultStr - the default String to return if the input is whitespace, empty ("") or null, may be null
Returns:: the passed in String, or the default
Since:: 2.6
See Also:: defaultString(String, String)

defaultIfEmpty

public static String defaultIfEmpty(String str,
                                    String defaultStr)

Returns either the passed in String, or if the String is empty or null, the value of defaultStr.

 StringUtils.defaultIfEmpty(null, "NULL")  = "NULL"
 StringUtils.defaultIfEmpty("", "NULL")    = "NULL"
 StringUtils.defaultIfEmpty("bat", "NULL") = "bat"
 StringUtils.defaultIfEmpty("", null)      = null

Parameters:: str - the String to check, may be null; defaultStr - the default String to return if the input is empty ("") or null, may be null
Returns:: the passed in String, or the default
See Also:: defaultString(String, String)

reverse
```
public static String reverse(String str)
```
Reverses a String as per StringBuilder.reverse().

A null String returns null.
```
 StringUtils.reverse(null)  = null
 StringUtils.reverse("")    = ""
 StringUtils.reverse("bat") = "tab"
 
```
Parameters:

str - the String to reverse, may be null

Returns:

the reversed String, null if null String input

reverseDelimited
```
public static String reverseDelimited(String str,
                                      char separatorChar)
```
Reverses a String that is delimited by a specific character.

The Strings between the delimiters are not reversed. Thus java.lang.String becomes String.lang.java (if the delimiter is '.').
```
 StringUtils.reverseDelimited(null, *)      = null
 StringUtils.reverseDelimited("", *)        = ""
 StringUtils.reverseDelimited("a.b.c", 'x') = "a.b.c"
 StringUtils.reverseDelimited("a.b.c", ".") = "c.b.a"
 
```
Parameters:

str - the String to reverse, may be null

separatorChar - the separator character to use

Returns:

the reversed String, null if null String input

Since:

2.0

reverse
```
public static void reverse(Object[] array)
```
Reverses the order of the given array.

There is no special handling for multi-dimensional arrays.

This method does nothing for a null input array.

Parameters:

array - the array to reverse, may be null

reverseDelimitedString
```
public static String reverseDelimitedString(String str,
                                            String separatorChars)
```
Deprecated. Use reverseDelimited(String, char) instead. This method is broken as the join doesn't know which char to use. Method will be removed in Commons Lang 3.0.
Reverses a String that is delimited by a specific character.

The Strings between the delimiters are not reversed. Thus java.lang.String becomes String.lang.java (if the delimiter is ".").
```
 StringUtils.reverseDelimitedString(null, *)       = null
 StringUtils.reverseDelimitedString("",*)          = ""
 StringUtils.reverseDelimitedString("a.b.c", null) = "a.b.c"
 StringUtils.reverseDelimitedString("a.b.c", ".")  = "c.b.a"
 
```
Parameters:

str - the String to reverse, may be null

separatorChars - the separator characters to use, null treated as whitespace

Returns:

the reversed String, null if null String input

abbreviate
```
public static String abbreviate(String str,
                                int maxWidth)
```
Abbreviates a String using ellipses. This will turn "Now is the time for all good men" into "Now is the time for..."

Specifically:
- If str is less than maxWidth characters long, return it.
- Else abbreviate it to (substring(str, 0, max-3) + "...") .
- If maxWidth is less than 4, throw an IllegalArgumentException.
- In no case will it return a String of length greater than maxWidth.
```
 StringUtils.abbreviate(null, *)      = null
 StringUtils.abbreviate("", 4)        = ""
 StringUtils.abbreviate("abcdefg", 6) = "abc..."
 StringUtils.abbreviate("abcdefg", 7) = "abcdefg"
 StringUtils.abbreviate("abcdefg", 8) = "abcdefg"
 StringUtils.abbreviate("abcdefg", 4) = "a..."
 StringUtils.abbreviate("abcdefg", 3) = IllegalArgumentException
 
```
Parameters:

str - the String to check, may be null

maxWidth - maximum length of result String, must be at least 4

Returns:

abbreviated String, null if null String input

Throws:

IllegalArgumentException - if the width is too small

Since:

2.0

abbreviate

public static String abbreviate(String str,
                                int offset,
                                int maxWidth)

Abbreviates a String using ellipses. This will turn "Now is the time for all good men" into "...is the time for..."

Works like abbreviate(String, int), but allows you to specify a "left edge" offset. Note that this left edge is not necessarily going to be the leftmost character in the result, or the first character following the ellipses, but it will appear somewhere in the result.

In no case will it return a String of length greater than maxWidth.

 StringUtils.abbreviate(null, *, *)                = null
 StringUtils.abbreviate("", 0, 4)                  = ""
 StringUtils.abbreviate("abcdefghijklmno", -1, 10) = "abcdefg..."
 StringUtils.abbreviate("abcdefghijklmno", 0, 10)  = "abcdefg..."
 StringUtils.abbreviate("abcdefghijklmno", 1, 10)  = "abcdefg..."
 StringUtils.abbreviate("abcdefghijklmno", 4, 10)  = "abcdefg..."
 StringUtils.abbreviate("abcdefghijklmno", 5, 10)  = "...fghi..."
 StringUtils.abbreviate("abcdefghijklmno", 6, 10)  = "...ghij..."
 StringUtils.abbreviate("abcdefghijklmno", 8, 10)  = "...ijklmno"
 StringUtils.abbreviate("abcdefghijklmno", 10, 10) = "...ijklmno"
 StringUtils.abbreviate("abcdefghijklmno", 12, 10) = "...ijklmno"
 StringUtils.abbreviate("abcdefghij", 0, 3)        = IllegalArgumentException
 StringUtils.abbreviate("abcdefghij", 5, 6)        = IllegalArgumentException

Parameters:: str - the String to check, may be null; offset - left edge of source String; maxWidth - maximum length of result String, must be at least 4
Returns:: abbreviated String, null if null String input
Throws:: IllegalArgumentException - if the width is too small
Since:: 2.0

abbreviateMiddle
```
public static String abbreviateMiddle(String str,
                                      String middle,
                                      int length)
```
Abbreviates a String to the length passed, replacing the middle characters with the supplied replacement String.

This abbreviation only occurs if the following criteria is met:
- Neither the String for abbreviation nor the replacement String are null or empty
- The length to truncate to is less than the length of the supplied String
- The length to truncate to is greater than 0
- The abbreviated String will have enough room for the length supplied replacement String and the first and last characters of the supplied String for abbreviation
Otherwise, the returned String will be the same as the supplied String for abbreviation.
```
 StringUtils.abbreviateMiddle(null, null, 0)      = null
 StringUtils.abbreviateMiddle("abc", null, 0)      = "abc"
 StringUtils.abbreviateMiddle("abc", ".", 0)      = "abc"
 StringUtils.abbreviateMiddle("abc", ".", 3)      = "abc"
 StringUtils.abbreviateMiddle("abcdef", ".", 4)     = "ab.f"
 
```
Parameters:

str - the String to abbreviate, may be null

middle - the String to replace the middle characters with, may be null

length - the length to abbreviate str to.

Returns:

the abbreviated String if the above criteria is met, or the original String supplied for abbreviation.

Since:

2.5

difference

public static String difference(String str1,
                                String str2)

Compares two Strings, and returns the portion where they differ. (More precisely, return the remainder of the second String, starting from where it's different from the first.)

For example, difference("i am a machine", "i am a robot") -> "robot".

 StringUtils.difference(null, null) = null
 StringUtils.difference("", "") = ""
 StringUtils.difference("", "abc") = "abc"
 StringUtils.difference("abc", "") = ""
 StringUtils.difference("abc", "abc") = ""
 StringUtils.difference("ab", "abxyz") = "xyz"
 StringUtils.difference("abcde", "abxyz") = "xyz"
 StringUtils.difference("abcde", "xyz") = "xyz"

Parameters:: str1 - the first String, may be null; str2 - the second String, may be null
Returns:: the portion of str2 where it differs from str1; returns the empty String if they are equal
Since:: 2.0

indexOfDifference

public static int indexOfDifference(String str1,
                                    String str2)

Compares two Strings, and returns the index at which the Strings begin to differ.

For example, indexOfDifference("i am a machine", "i am a robot") -> 7

 StringUtils.indexOfDifference(null, null) = -1
 StringUtils.indexOfDifference("", "") = -1
 StringUtils.indexOfDifference("", "abc") = 0
 StringUtils.indexOfDifference("abc", "") = 0
 StringUtils.indexOfDifference("abc", "abc") = -1
 StringUtils.indexOfDifference("ab", "abxyz") = 2
 StringUtils.indexOfDifference("abcde", "abxyz") = 2
 StringUtils.indexOfDifference("abcde", "xyz") = 0

Parameters:: str1 - the first String, may be null; str2 - the second String, may be null
Returns:: the index where str2 and str1 begin to differ; -1 if they are equal
Since:: 2.0

indexOfDifference

public static int indexOfDifference(String[] strs)

Compares all Strings in an array and returns the index at which the Strings begin to differ.

For example, indexOfDifference(new String[] {"i am a machine", "i am a robot"}) -> 7

 StringUtils.indexOfDifference(null) = -1
 StringUtils.indexOfDifference(new String[] {}) = -1
 StringUtils.indexOfDifference(new String[] {"abc"}) = -1
 StringUtils.indexOfDifference(new String[] {null, null}) = -1
 StringUtils.indexOfDifference(new String[] {"", ""}) = -1
 StringUtils.indexOfDifference(new String[] {"", null}) = 0
 StringUtils.indexOfDifference(new String[] {"abc", null, null}) = 0
 StringUtils.indexOfDifference(new String[] {null, null, "abc"}) = 0
 StringUtils.indexOfDifference(new String[] {"", "abc"}) = 0
 StringUtils.indexOfDifference(new String[] {"abc", ""}) = 0
 StringUtils.indexOfDifference(new String[] {"abc", "abc"}) = -1
 StringUtils.indexOfDifference(new String[] {"abc", "a"}) = 1
 StringUtils.indexOfDifference(new String[] {"ab", "abxyz"}) = 2
 StringUtils.indexOfDifference(new String[] {"abcde", "abxyz"}) = 2
 StringUtils.indexOfDifference(new String[] {"abcde", "xyz"}) = 0
 StringUtils.indexOfDifference(new String[] {"xyz", "abcde"}) = 0
 StringUtils.indexOfDifference(new String[] {"i am a machine", "i am a robot"}) = 7

Parameters:: strs - array of strings, entries may be null
Returns:: the index where the strings begin to differ; -1 if they are all equal
Since:: 2.4

getCommonPrefix

public static String getCommonPrefix(String[] strs)

Compares all Strings in an array and returns the initial sequence of characters that is common to all of them.

For example, getCommonPrefix(new String[] {"i am a machine", "i am a robot"}) -> "i am a "

 StringUtils.getCommonPrefix(null) = ""
 StringUtils.getCommonPrefix(new String[] {}) = ""
 StringUtils.getCommonPrefix(new String[] {"abc"}) = "abc"
 StringUtils.getCommonPrefix(new String[] {null, null}) = ""
 StringUtils.getCommonPrefix(new String[] {"", ""}) = ""
 StringUtils.getCommonPrefix(new String[] {"", null}) = ""
 StringUtils.getCommonPrefix(new String[] {"abc", null, null}) = ""
 StringUtils.getCommonPrefix(new String[] {null, null, "abc"}) = ""
 StringUtils.getCommonPrefix(new String[] {"", "abc"}) = ""
 StringUtils.getCommonPrefix(new String[] {"abc", ""}) = ""
 StringUtils.getCommonPrefix(new String[] {"abc", "abc"}) = "abc"
 StringUtils.getCommonPrefix(new String[] {"abc", "a"}) = "a"
 StringUtils.getCommonPrefix(new String[] {"ab", "abxyz"}) = "ab"
 StringUtils.getCommonPrefix(new String[] {"abcde", "abxyz"}) = "ab"
 StringUtils.getCommonPrefix(new String[] {"abcde", "xyz"}) = ""
 StringUtils.getCommonPrefix(new String[] {"xyz", "abcde"}) = ""
 StringUtils.getCommonPrefix(new String[] {"i am a machine", "i am a robot"}) = "i am a "

Parameters:: strs - array of String objects, entries may be null
Returns:: the initial sequence of characters that are common to all Strings in the array; empty String if the array is null, the elements are all null or if there is no common prefix.
Since:: 2.4

getLevenshteinDistance

public static int getLevenshteinDistance(String s,
                                         String t)

Find the Levenshtein distance between two Strings.

This is the number of changes needed to change one String into another, where each change is a single character modification (deletion, insertion or substitution).

The previous implementation of the Levenshtein distance algorithm was from http://www.merriampark.com /ld.htm

Chas Emerick has written an implementation in Java, which avoids an OutOfMemoryError which can occur when my Java implementation is used with very large strings.
This implementation of the Levenshtein distance algorithm is from http://www.merriampark.com/ ldjava.htm

 StringUtils.getLevenshteinDistance(null, *)             = IllegalArgumentException
 StringUtils.getLevenshteinDistance(*, null)             = IllegalArgumentException
 StringUtils.getLevenshteinDistance("","")               = 0
 StringUtils.getLevenshteinDistance("","a")              = 1
 StringUtils.getLevenshteinDistance("aaapppp", "")       = 7
 StringUtils.getLevenshteinDistance("frog", "fog")       = 1
 StringUtils.getLevenshteinDistance("fly", "ant")        = 3
 StringUtils.getLevenshteinDistance("elephant", "hippo") = 7
 StringUtils.getLevenshteinDistance("hippo", "elephant") = 7
 StringUtils.getLevenshteinDistance("hippo", "zzzzzzzz") = 8
 StringUtils.getLevenshteinDistance("hello", "hallo")    = 1

Parameters:: s - the first String, must not be null; t - the second String, must not be null
Returns:: result distance
Throws:: IllegalArgumentException - if either String input null

startsWith
```
public static boolean startsWith(String str,
                                 String prefix)
```
Check if a String starts with a specified prefix.

nulls are handled without exceptions. Two null references are considered to be equal. The comparison is case sensitive.
```
 StringUtils.startsWith(null, null)      = true
 StringUtils.startsWith(null, "abc")     = false
 StringUtils.startsWith("abcdef", null)  = false
 StringUtils.startsWith("abcdef", "abc") = true
 StringUtils.startsWith("ABCDEF", "abc") = false
 
```
Parameters:

str - the String to check, may be null

prefix - the prefix to find, may be null

Returns:

true if the String starts with the prefix, case sensitive, or both null

Since:

2.4

See Also:

String.startsWith(String)

startsWithIgnoreCase

public static boolean startsWithIgnoreCase(String str,
                                           String prefix)

Case insensitive check if a String starts with a specified prefix.

nulls are handled without exceptions. Two null references are considered to be equal. The comparison is case insensitive.

 StringUtils.startsWithIgnoreCase(null, null)      = true
 StringUtils.startsWithIgnoreCase(null, "abc")     = false
 StringUtils.startsWithIgnoreCase("abcdef", null)  = false
 StringUtils.startsWithIgnoreCase("abcdef", "abc") = true
 StringUtils.startsWithIgnoreCase("ABCDEF", "abc") = true

Parameters:: str - the String to check, may be null; prefix - the prefix to find, may be null
Returns:: true if the String starts with the prefix, case insensitive, or both null
Since:: 2.4
See Also:: String.startsWith(String)

startsWithAny

public static boolean startsWithAny(String string,
                                    String[] searchStrings)

Check if a String starts with any of an array of specified strings.

 StringUtils.startsWithAny(null, null)      = false
 StringUtils.startsWithAny(null, new String[] {"abc"})  = false
 StringUtils.startsWithAny("abcxyz", null)     = false
 StringUtils.startsWithAny("abcxyz", new String[] {""}) = false
 StringUtils.startsWithAny("abcxyz", new String[] {"abc"}) = true
 StringUtils.startsWithAny("abcxyz", new String[] {null, "xyz", "abc"}) = true

Parameters:: string - the String to check, may be null; searchStrings - the Strings to find, may be null or empty
Returns:: true if the String starts with any of the the prefixes, case insensitive, or both null
Since:: 2.5
See Also:: startsWith(String, String)

endsWith

public static boolean endsWith(String str,
                               String suffix)

Check if a String ends with a specified suffix.

nulls are handled without exceptions. Two null references are considered to be equal. The comparison is case sensitive.

 StringUtils.endsWith(null, null)      = true
 StringUtils.endsWith(null, "def")     = false
 StringUtils.endsWith("abcdef", null)  = false
 StringUtils.endsWith("abcdef", "def") = true
 StringUtils.endsWith("ABCDEF", "def") = false
 StringUtils.endsWith("ABCDEF", "cde") = false

Parameters:: str - the String to check, may be null; suffix - the suffix to find, may be null
Returns:: true if the String ends with the suffix, case sensitive, or both null
Since:: 2.4
See Also:: String.endsWith(String)

endsWithIgnoreCase

public static boolean endsWithIgnoreCase(String str,
                                         String suffix)

Case insensitive check if a String ends with a specified suffix.

nulls are handled without exceptions. Two null references are considered to be equal. The comparison is case insensitive.

 StringUtils.endsWithIgnoreCase(null, null)      = true
 StringUtils.endsWithIgnoreCase(null, "def")     = false
 StringUtils.endsWithIgnoreCase("abcdef", null)  = false
 StringUtils.endsWithIgnoreCase("abcdef", "def") = true
 StringUtils.endsWithIgnoreCase("ABCDEF", "def") = true
 StringUtils.endsWithIgnoreCase("ABCDEF", "cde") = false

Parameters:: str - the String to check, may be null; suffix - the suffix to find, may be null
Returns:: true if the String ends with the suffix, case insensitive, or both null
Since:: 2.4
See Also:: String.endsWith(String)

normalizeSpace
```
public static String normalizeSpace(String str)
```
Similar to http:// www.w3.org/TR/xpath/#function-normalize -space

The function returns the argument string with whitespace normalized by using trim(String) to remove leading and trailing whitespace and then replacing sequences of whitespace characters by a single space.
In XML Whitespace characters are the same as those allowed by the S production, which is S ::= (#x20 | #x9 | #xD | #xA)+
See Java's Character.isWhitespace(char) for which characters are considered whitespace.
The difference is that Java's whitespace includes vertical tab and form feed, which this functional will also normalize. Additonally trim(String) removes control characters (char <= 32) from both ends of this String.

Parameters:

str - the source String to normalize whitespaces from, may be null

Returns:

the modified string with whitespace normalized, null if null String input

Since:

2.6

See Also:

Character.isWhitespace(char), trim(String), http: //www.w3.org/TR/xpath/#function-normalize-space

endsWithAny

public static boolean endsWithAny(String string,
                                  String[] searchStrings)

Check if a String ends with any of an array of specified strings.

 StringUtils.endsWithAny(null, null)      = false
 StringUtils.endsWithAny(null, new String[] {"abc"})  = false
 StringUtils.endsWithAny("abcxyz", null)     = false
 StringUtils.endsWithAny("abcxyz", new String[] {""}) = true
 StringUtils.endsWithAny("abcxyz", new String[] {"xyz"}) = true
 StringUtils.endsWithAny("abcxyz", new String[] {null, "xyz", "abc"}) = true

Parameters:: string - the String to check, may be null; searchStrings - the Strings to find, may be null or empty
Returns:: true if the String ends with any of the the prefixes, case insensitive, or both null
Since:: 2.6

pluralize
```
public static String pluralize(String word)
```
Pluralize.

Parameters:

word - the word

Returns:

the plural of word. This is done by applying a few rules. These cover most (but not all) cases: 1. If the word ends in s, ss, x, o, or ch, append es 2. If the word ends in a consonant followed by y, drop the y and add ies 3. Append an s and call it a day. The ultimate references is at http://en.wikipedia.org/wiki/English_plural

Class StringUtils

Field Summary

Fields inherited from interface com.varra.util.StringPool

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

EMPTY_STRING_ARRAY

EMPTY

INDEX_NOT_FOUND

Constructor Detail

StringUtils

Method Detail

isEmpty

isEmpty

isEmpty

isEmpty

isEmpty

isEmpty

isEmpty

isEmpty

isEmpty

isNotEmpty

isNotEmpty

isNotEmpty

isNotEmpty

isNotEmpty

isNotEmpty

isNotEmpty

isNotEmpty

isNotEmpty

isEmpty

isNotEmpty

isBlank

isNotBlank

clean

trim

trimToNull

trimToEmpty

strip

stripToNull

stripToEmpty

strip

stripStart

stripEnd

stripAll

stripAll

equals

equalsOfAny

equalsIgnoreCase

equalsOfAnyIgnoreCase

indexOf

indexOf

indexOf

ordinalIndexOf

indexOf

indexOfIgnoreCase

indexOfIgnoreCase

lastIndexOf

lastIndexOf

lastIndexOf

lastOrdinalIndexOf

lastIndexOf

lastIndexOfIgnoreCase

lastIndexOfIgnoreCase

contains

contains

containsIgnoreCase

indexOfAny

isHighSurrogate

indexOfAny

containsAny

containsAny

indexOfAnyBut

indexOfAnyBut

containsOnly

containsOnly

containsNone

containsNone

indexOfAny