Swing58.java

import javax.swing.*;
import javax.swing.tree.DefaultMutableTreeNode;

public class Swing58 {
    public static void main(String[] args) {

        JFrame frame = new JFrame("JTree");
        frame.setSize(500,500);

        DefaultMutableTreeNode rootNode = new DefaultMutableTreeNode("Top");

        DefaultMutableTreeNode A = new DefaultMutableTreeNode("A");
        DefaultMutableTreeNode B = new DefaultMutableTreeNode("B");
        DefaultMutableTreeNode A1 = new DefaultMutableTreeNode("A1");
        DefaultMutableTreeNode A2 = new DefaultMutableTreeNode("A2");
        DefaultMutableTreeNode B1 = new DefaultMutableTreeNode("B1");
        DefaultMutableTreeNode B2 = new DefaultMutableTreeNode("B2");
        DefaultMutableTreeNode B3 = new DefaultMutableTreeNode("B3");

        A.add(A1);
        A.add(A2);
        B.add(B1);
        B.add(B2);
        B.add(B3);

        rootNode.add(A);
        rootNode.add(B);

        JTree tree = new JTree(rootNode);
        frame.add(tree);
        frame.setVisible(true);
    }
}