How to draw a tree representing a graph of connected nodes?

The simplest way I can think of is to write a class that extends JPanel and override its paintComponent() method. In the paint method you can iterate through the tree and paint each node. Here is a short example:

import java.awt.Graphics;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class JPanelTest extends JPanel {

    @Override
    public void paintComponent(Graphics g) {
        // Draw Tree Here
        g.drawOval(5, 5, 25, 25);
    }

    public static void main(String[] args) {
        JFrame jFrame = new JFrame();
        jFrame.add(new JPanelTest());
        jFrame.setSize(500, 500);
        jFrame.setVisible(true);
    }

}

Take a stab at painting the tree, if you can't figure it out post what you've tried in your question.

I'd say it's worth to check out Abego's TreeLayout too. It's essentially a tree layout algorithm so it can be used with any drawing mechanism, but it also contains some demos/examples of drawing graphs in SVG and Swing.

You might consider any of these:

• JHotDraw, cited here, a meta-library for creating custom graph editors.

• Prefuse visualization library, illustrated here and here.

• Batik, which implements SVG rendering.

• JGraph demo and user manual.

• GraphStream, illustrated here.

• JFreeChart XYBubbleRenderer

• A JTree, suggested here, with a custom TreeIcon.

• A custom renderer, with x based on a fraction of tree breadth and y based on recursion level.

• A simple graph editor such as draw.GraphPanel, illustrated here.