Package org.graphstream.stream.file

Class FileSourceNCol

java.lang.Object

org.graphstream.stream.SourceBase

org.graphstream.stream.file.FileSourceBase

org.graphstream.stream.file.FileSourceNCol

All Implemented Interfaces:

FileSource, Source

public class FileSourceNCol
extends FileSourceBase

Reader for the "ncol" graph format.

The ncol graph format is a simple format where each line describes an edge by giving two node names and an optional third parameters giving the edge weight. The nodes are created implicitly.

Also, the format does not specify any direction for edges. By default all edges are undirected. It is specified in the format that you will never have directed edges and that the lines:

     node1Name node2Name
 

and

     node2Name node1Name
 

Cannot both appear at the same time in a file.

This format only contains edges. To ensure the "add node" events are sent before an edge referencing two nodes is created via an "add edge" event, this reader has a hash set of already encountered nodes. The hash set allows to issue "add node" events only when a node is encountered for the first time.

This hash set consumes memory, but is the only way to ensure "add node" events are correctly issued. If this input is directly connected to a graph, as graphs can create non-existing nodes automatically, you can disable the hash set of nodes using the constructor FileSourceNCol(boolean), and giving "false" for the first argument.

The usual file name extension for this format is ".ncol".

Nested Class Summary

Nested classes/interfaces inherited from class org.graphstream.stream.SourceBase

SourceBase.ElementType

Constructor Summary

Constructors

Constructor	Description
FileSourceNCol()	New reader for the "ncol" format.
FileSourceNCol(boolean declareNodes)	New reader for the "ncol" format.

Method Summary

Modifier and Type	Method	Description
void	begin(InputStream stream)	Begin reading the file stopping as soon as possible.
void	begin(Reader reader)	Begin reading the file stopping as soon as possible.
void	begin(String filename)	Begin reading the file stopping as soon as possible.
void	begin(URL url)	Begin reading the file stopping as soon as possible.
void	end()	Finish the reading process (even if FileSource.nextEvents() or FileSource.nextStep() did not returned false).
boolean	nextEvents()	Try to process one graph event, or as few as possible, if more must be read at once.
boolean	nextStep()	Try to process all the events occurring during one time step.

Methods inherited from class org.graphstream.stream.file.FileSourceBase

addAttributeClass, readAll, readAll, readAll, readAll

Methods inherited from class org.graphstream.stream.SourceBase

addAttributeSink, addElementSink, addSink, attributeSinks, clearAttributeSinks, clearElementSinks, clearSinks, elementSinks, removeAttributeSink, removeElementSink, removeSink, sendAttributeChangedEvent, sendAttributeChangedEvent, sendEdgeAdded, sendEdgeAdded, sendEdgeAttributeAdded, sendEdgeAttributeAdded, sendEdgeAttributeChanged, sendEdgeAttributeChanged, sendEdgeAttributeRemoved, sendEdgeAttributeRemoved, sendEdgeRemoved, sendEdgeRemoved, sendGraphAttributeAdded, sendGraphAttributeAdded, sendGraphAttributeChanged, sendGraphAttributeChanged, sendGraphAttributeRemoved, sendGraphAttributeRemoved, sendGraphCleared, sendGraphCleared, sendNodeAdded, sendNodeAdded, sendNodeAttributeAdded, sendNodeAttributeAdded, sendNodeAttributeChanged, sendNodeAttributeChanged, sendNodeAttributeRemoved, sendNodeAttributeRemoved, sendNodeRemoved, sendNodeRemoved, sendStepBegins, sendStepBegins

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.graphstream.stream.Source

addAttributeSink, addElementSink, addSink, clearAttributeSinks, clearElementSinks, clearSinks, removeAttributeSink, removeElementSink, removeSink

Constructor Details

FileSourceNCol

public FileSourceNCol()

New reader for the "ncol" format.

FileSourceNCol

public FileSourceNCol(boolean declareNodes)

New reader for the "ncol" format.

Parameters:

declareNodes - If true (default=true) this reader outputs nodeAdded events.

Method Details

nextEvents

public boolean nextEvents() throws IOException

Description copied from interface: FileSource

Try to process one graph event, or as few as possible, if more must be read at once. For this method to work, you must have called FileSource.begin(InputStream) or FileSource.begin(String) before. This method return true while there are still events to read.

Specified by:

nextEvents in interface FileSource

Specified by:

nextEvents in class FileSourceBase

Returns:

true if there are still events to read, false as soon as the file is finished.

Throws:

IOException - If an I/O error occurs while reading.

begin

public void begin(String filename) throws IOException

Description copied from interface: FileSource

Begin reading the file stopping as soon as possible. Next graph events stored in the file will be sent by calling FileSource.nextEvents() or FileSource.nextStep(). Once begin() has been called, you must finish the reading process using FileSource.end(). You cannot call begin() twice without having called FileSource.end() in between.

Specified by:

begin in interface FileSource

Overrides:

begin in class FileSourceBase

Parameters:

filename - Name of the file to read.

Throws:

IOException - If an I/O error occurs while reading.

begin

public void begin(URL url) throws IOException

Description copied from interface: FileSource

Begin reading the file stopping as soon as possible. Next graph events stored in the file will be sent by calling FileSource.nextEvents() or FileSource.nextStep(). Once begin() has been called, you must finish the reading process using FileSource.end(). You cannot call begin() twice without having called FileSource.end() in between.

Specified by:

begin in interface FileSource

Overrides:

begin in class FileSourceBase

Parameters:

url - The URL of the file to read.

Throws:

IOException - If an I/O error occurs while reading.

begin

public void begin(InputStream stream) throws IOException

Description copied from interface: FileSource

Begin reading the file stopping as soon as possible. Next graph events stored in the file will be sent by calling FileSource.nextEvents() or FileSource.nextStep(). Once begin() has been called, you must finish the reading process using FileSource.end(). You cannot call begin() twice without having called FileSource.end() in between.

Specified by:

begin in interface FileSource

Overrides:

begin in class FileSourceBase

Parameters:

stream - The input stream to use for reading.

Throws:

IOException - If an I/O error occurs while reading.

begin

public void begin(Reader reader) throws IOException

Description copied from interface: FileSource

Begin reading the file stopping as soon as possible. Next graph events stored in the file will be sent by calling FileSource.nextEvents() or FileSource.nextStep(). Once begin() has been called, you must finish the reading process using FileSource.end(). You cannot call begin() twice without having called FileSource.end() in between.

Specified by:

begin in interface FileSource

Overrides:

begin in class FileSourceBase

Parameters:

reader - The file reader to use.

Throws:

IOException - If an I/O error occurs while reading.

nextStep

public boolean nextStep() throws IOException

Description copied from interface: FileSource

Try to process all the events occurring during one time step. In GraphStream, a time step is a group of events that are considered occurring at the same time. Most file formats do not have this notion of step. The DGS format designed for GraphStream handles steps. This method return true while there are still events to read.

Returns:

true if there are still events to read, false as soon as the file is finished.

Throws:

IOException - If an I/O error occurs while reading.

end

public void end() throws IOException

Description copied from interface: FileSource

Finish the reading process (even if FileSource.nextEvents() or FileSource.nextStep() did not returned false). You must call this method after reading.

Specified by:

end in interface FileSource

Overrides:

end in class FileSourceBase

Throws:

IOException - If an I/O error occurs while closing the file.