public final class Preconditions
extends java.lang.Object
if (count <= 0) { throw new IllegalArgumentException("must be positive: " + count); }to be replaced with the more compact
checkArgument(count > 0, "must be positive: %s", count);
Note that the sense of the expression is inverted; with Preconditions
you declare what you expect to be true, just as you
do with an
assert
or a JUnit assertTrue
call.
Modifier and Type | Method and Description |
---|---|
static void |
checkArgument(boolean expression,
java.lang.Object errorMessage)
Ensures the truth of an expression involving one or more parameters to the
calling method.
|
static void |
checkArgument(boolean expression,
java.lang.String errorMessageTemplate,
java.lang.Object... errorMessageArgs)
Ensures the truth of an expression involving one or more parameters to the
calling method.
|
static <T> T |
checkNotNull(T reference,
java.lang.Object errorMessage)
Ensures that an object reference passed as a parameter to the calling
method is not null.
|
public static void checkArgument(boolean expression, java.lang.Object errorMessage)
expression
- a boolean expressionerrorMessage
- the exception message to use if the check fails; will
be converted to a string using String.valueOf(Object)
if
not null (a null will not be converted).java.lang.IllegalArgumentException
- if expression
is falsepublic static void checkArgument(boolean expression, java.lang.String errorMessageTemplate, java.lang.Object... errorMessageArgs)
expression
- a boolean expressionerrorMessageTemplate
- a template for the exception message should the
check fail. The message is formed using String.format(String, Object...)
.
if not null (a null will not be converted).errorMessageArgs
- the arguments to be substituted into the message
template.java.lang.IllegalArgumentException
- if expression
is falsepublic static <T> T checkNotNull(T reference, java.lang.Object errorMessage)
reference
- an object referenceerrorMessage
- the exception message to use if the check fails; will
be converted to a string using String.valueOf(Object)
java.lang.NullPointerException
- if reference
is null