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

Question

I want to display a tree in a Java GUI, but I dont know how. The tree represents a graph of connected nodes, like this:

I should say that I have my own tree class:

public class BinaryTree   { private BinaryNode root; public BinaryTree( ) {     root = null; }  public BinaryTree( Object rootItem ) {     root = new BinaryNode( rootItem, null, null ); }  public BinaryTree( Object rootItem,BinaryNode a,BinaryNode b ) {     root = new BinaryNode( rootItem, a, b ); }  public int leavesCount(){     return BinaryNode.leavesCount(root); }  public boolean equal(BinaryTree a,BinaryTree b){     return BinaryNode.equal(a.root, b.root);  }  public void printPreOrder( ) {     if( root != null )         root.printPreOrder( ); }  public void printInOrder( ) {     if( root != null )        root.printInOrder( ); }  public void printPostOrder( ) {     if( root != null )        root.printPostOrder( ); }  public void makeEmpty( ) {     root = null; }   public boolean isEmpty( ) {     return root == null; }   public void merge( Object rootItem, BinaryTree t1, BinaryTree t2 ) throws MergeAbrot {     if( t1.root == t2.root && t1.root != null )     {          throw new MergeAbrot("MergeAbrot");      }       root=new BinaryNode( rootItem, t1.root, t2.root );      if( this != t1 )         t1.root = null;     if( this != t2 )        t2.root = null; }  public int size( ) {     return BinaryNode.size( root ); }  public int height( ) {     return BinaryNode.height( root ); }  } 

I only want to draw the tree. How should I do?

Answer 1

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.

Answer 2

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.

Answer 3

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.

Answer 4

I guess you just need to read about JTree: http://docs.oracle.com/javase/tutorial/uiswing/components/tree.html

And maybe some other general information about Swing