Swing - JTree

Here's a code on how to use JTree:

import javax.swing.*;

import javax.swing.tree.*;

public class Main{

    public static void main(String[] args){

        new Main();

    }

    public Main(){

        frame = new JFrame("JTree Application");

        root = new DefaultMutableTreeNode("World");

        DefaultMutableTreeNode usa = new 

                           DefaultMutableTreeNode("USA");

        root.add(usa);

        DefaultMutableTreeNode id = new   

                           DefaultMutableTreeNode("Indonesia");

        root.add(id);

        DefaultMutableTreeNode ny = new 

                           DefaultMutableTreeNode("New York");

        usa.add(ny);

        DefaultMutableTreeNode ca = new 

                           DefaultMutableTreeNode("California");

        usa.add(ca);

        DefaultMutableTreeNode jkt = new 

                           DefaultMutableTreeNode("Jakarta");

        id.add(jkt);

        DefaultMutableTreeNode dp = new 

                           DefaultMutableTreeNode("Denpasar");

        id.add(dp);

        model = new DefaultTreeModel(root);

        tData = new JTree(model);

        frame.add(new JScrollPane(tData));

        frame.setSize(400, 300);

        frame.setLocation(200, 100);

        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        frame.setVisible(true);

    }

    private JFrame frame;

    private JTree tData;  

    private DefaultTreeModel model;

    private DefaultMutableTreeNode root;

Swing - JTree