Java Swing radio button on change event listener

/**
 * @author L a u tturi.com
 * Java Swing Example: add change listener to radio button /
 handle radio button change event in java swing
 */

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JRadioButton;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;

public class Lautturi {
	public static void main(String[] args) {
		JFrame frame = new JFrame("Java Swing - lautturi");

		JPanel panel = new JPanel();
		JButton button1 = new JButton("button1");
		panel.add(button1);
		frame.add(panel);
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.setSize(500, 300);
		frame.setLocationRelativeTo(null);
		
		// Create a Radio Button
		JRadioButton radioButton = new JRadioButton(); 	
		// Add JRadioButton to panel.
		panel.add(radioButton);
		
		// add change listener to radio button
		radioButton.addChangeListener(new ChangeListener() {
			@Override
			public void stateChanged(ChangeEvent e) {
				// Check if button is selected
				boolean isSelected = radioButton.isSelected(); 	
				if(isSelected) {
					JOptionPane.showMessageDialog(frame,
						    "Title",
						    "The radio button is selected",
						    JOptionPane.WARNING_MESSAGE);
				}
				
			}
		});

		frame.setVisible(true);
	}
}