Documentation / Tutorials

Reading files using FileSource

File sources allow to turn a file into a source of events for a graph. There are two ways to make this : reading the whole file in a single instruction, or reading the file event by event. Some file formats do not support to be read in the event-by-event way. Actually, GraphStream is able to read the following file format :

• DGS (GraphStream)
• DOT (GraphViz)
• GML
• TLP (Tulip)
• NET (Pajek)
• GraphML
• GEXF (Gephi)

File sources are source of events, so a sink has to be added to the source to have some effect :

import org.graphstream.graph.Graph;
import org.graphstream.graph.implementations.DefaultGraph;
import org.graphstream.stream.file.FileSource;

public class TutorialFileSource {
	public static void main(String ... args) {
		Graph g = new DefaultGraph("g");
		FileSource fs = ... ;

		fs.addSink(g);

		...
	}
}

Read a whole file in a single instruction

FileSource provides readAll(XXX) methods which can be used with an InputStream, a Reader, or just a file path.

Graph g = ... ;
FileSource fs = ... ;

fs.addSink(g);

try {
	fs.readAll("path/to/my/graph");
} catch( IOException e) {
	...
} finally {
	fs.removeSink(g);
}

Read a file event-by-event

Event-by-event reading is done using three methods :

1. begin(xxx), where xxx is an InputStream, a Reader or a String; this method is used to open the source, possibly by producing some events;
2. nextEvents() or nextStep() : read some events; nextStep() can be used in format supporting time step to read a block of events, in the DGS format for example;
3. end() : close the source and attached ressources.

Reading can be done in this way :

Graph g = ... ;
FileSource fs = ... ;

fs.addSink(g);

try {
	fs.begin("path/to/my/graph");

	while (fs.nextEvents()) {
	// Optionally some code here ...
	}
} catch( IOException e) {
	...
}

// Here we use a second try/catch block rather than a big one
// to be sure to call the end() method even if there is some
// troubles while reading events.
try {
	fs.end();
} catch( IOException e) {
	...
} finally {
	fs.removeSink(g);
}

File source factory

It is possible to let GraphStream choose the right file source to read a file using FileSourceFactory :

Graph g = ... ;
FileSource fs = FileSourceFactory.sourceFor("path/to/my/file");

...

##Full example code

import org.graphstream.graph.Graph;
import org.graphstream.graph.implementations.DefaultGraph;
import org.graphstream.stream.file.FileSource;
import org.graphstream.stream.file.FileSourceFactory;

import java.io.IOException;

public class TutorialFileSource {

	public static void main(String ... args) {
		String filePath = "...";
		Graph g = new DefaultGraph("g");
		FileSource fs = FileSourceFactory.sourceFor(filePath);

		fs.addSink(g);

		try {
			fs.begin(filePath);

			while (fs.nextEvents()) {
				// Optionally some code here ...
			}
		} catch( IOException e) {
			e.printStackTrace();
		}

		try {
			fs.end();
		} catch( IOException e) {
			e.printStackTrace();
		} finally {
			fs.removeSink(g);
		}
	}
}