Main.java Source code

Introduction

Here is the source code for Main.java

Source

import java.awt.BorderLayout;

import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTree;
import javax.swing.event.TreeExpansionEvent;
import javax.swing.event.TreeWillExpandListener;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.ExpandVetoException;
import javax.swing.tree.TreePath;

public class Main {
    public static void main(String args[]) {
        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        DefaultMutableTreeNode root = new DefaultMutableTreeNode("Root");
        root.add(new DefaultMutableTreeNode("A"));
        root.add(new DefaultMutableTreeNode("B"));
        root.add(new DefaultMutableTreeNode("C"));
        JTree tree = new JTree(root);

        TreeWillExpandListener treeWillExpandListener = new TreeWillExpandListener() {
            public void treeWillCollapse(TreeExpansionEvent treeExpansionEvent) throws ExpandVetoException {
                TreePath path = treeExpansionEvent.getPath();
                DefaultMutableTreeNode node = (DefaultMutableTreeNode) path.getLastPathComponent();
                String data = node.getUserObject().toString();
                System.out.println("WillCollapse: " + data);

            }

            public void treeWillExpand(TreeExpansionEvent treeExpansionEvent) throws ExpandVetoException {
                TreePath path = treeExpansionEvent.getPath();
                DefaultMutableTreeNode node = (DefaultMutableTreeNode) path.getLastPathComponent();
                String data = node.getUserObject().toString();
                System.out.println("WillExpand: " + data);

            }
        };

        tree.addTreeWillExpandListener(treeWillExpandListener);

        JScrollPane scrollPane = new JScrollPane(tree);
        frame.add(scrollPane, BorderLayout.CENTER);
        frame.setSize(300, 150);
        frame.setVisible(true);

    }
}