Put a String on the edge of JUNG graph - jung

Question

I'm trying to put a String text to an edge of a JUNG tree graph. See bellow example.
What I tried is to simply add this line:
graph.addEdge("arrow", "Vmain", "Vsecond");
... but without any results (see bellow screenshot). I need some advices please.
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.BorderFactory;
import javax.swing.JApplet;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JPanel;
import org.apache.commons.collections15.Factory;
import edu.uci.ics.jung.algorithms.layout.TreeLayout;
import edu.uci.ics.jung.graph.DirectedGraph;
import edu.uci.ics.jung.graph.DirectedSparseMultigraph;
import edu.uci.ics.jung.graph.Forest;
import edu.uci.ics.jung.graph.DelegateForest;
import edu.uci.ics.jung.graph.DelegateTree;
import edu.uci.ics.jung.graph.Tree;
import edu.uci.ics.jung.visualization.GraphZoomScrollPane;
import edu.uci.ics.jung.visualization.VisualizationViewer;
import edu.uci.ics.jung.visualization.control.CrossoverScalingControl;
import edu.uci.ics.jung.visualization.control.DefaultModalGraphMouse;
import edu.uci.ics.jung.visualization.control.ModalGraphMouse;
import edu.uci.ics.jung.visualization.control.ScalingControl;
import edu.uci.ics.jung.visualization.decorators.EdgeShape;
import edu.uci.ics.jung.visualization.decorators.ToStringLabeller;
public class TreeVisualiser extends JApplet {
Forest<String, String> graph;
Factory<DirectedGraph<String, String>> graphFactory = new Factory<DirectedGraph<String, String>>() {
public DirectedGraph<String, String> create() {
return new DirectedSparseMultigraph<String, String>();
}
};
Factory<Tree<String, String>> treeFactory = new Factory<Tree<String, String>>() {
public Tree<String, String> create() {
return new DelegateTree<String, String>(graphFactory);
}
};
VisualizationViewer<String, String> vv;
String root;
TreeLayout<String, String> treeLayout;
#SuppressWarnings({"rawtypes", "unchecked"})
public TreeVisualiser() {
// create a simple graph for the demo
graph = new DelegateForest<String, String>();
createTree();
treeLayout = new TreeLayout<String, String>(graph);
vv = new VisualizationViewer<String, String>(treeLayout, new Dimension(600, 600));
vv.setBackground(Color.white);
vv.getRenderContext().setEdgeShapeTransformer(new EdgeShape.Line());
vv.getRenderContext().setVertexLabelTransformer(new ToStringLabeller());
// add a listener for ToolTips
vv.setVertexToolTipTransformer(new ToStringLabeller());
Container content = getContentPane();
final GraphZoomScrollPane panel = new GraphZoomScrollPane(vv);
content.add(panel);
final DefaultModalGraphMouse graphMouse = new DefaultModalGraphMouse();
vv.setGraphMouse(graphMouse);
JComboBox modeBox = graphMouse.getModeComboBox();
modeBox.addItemListener(graphMouse.getModeListener());
graphMouse.setMode(ModalGraphMouse.Mode.TRANSFORMING);
final ScalingControl scaler = new CrossoverScalingControl();
JButton plus = new JButton("+");
plus.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
scaler.scale(vv, 1.1f, vv.getCenter());
}
});
JButton minus = new JButton("-");
minus.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
scaler.scale(vv, 1 / 1.1f, vv.getCenter());
}
});
JPanel scaleGrid = new JPanel(new GridLayout(1, 0));
scaleGrid.setBorder(BorderFactory.createTitledBorder("Zoom"));
JPanel controls = new JPanel();
scaleGrid.add(plus);
scaleGrid.add(minus);
controls.add(scaleGrid);
controls.add(modeBox);
content.add(controls, BorderLayout.SOUTH);
}
private void createTree() {
graph.addEdge("arrow", "Vmain", "Vsecond");
}
public static void main(String[] args) {
JFrame frame = new JFrame();
Container content = frame.getContentPane();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
content.add(new TreeVisualiser());
frame.pack();
frame.setVisible(true);
}
}

Answer 1

Oh, I missed this line of code. Now it is working as I want.
vv.getRenderContext().setEdgeLabelTransformer(new ToStringLabeller());