Adding a listener to close button on a JFrame

Question

can I add an action listener to the 'x' button on a JFrame? i want to ask the user if they wish to save when they click the close button on the JFrame...
thanks.

Answer 1

Set the default close operation on your frame to do nothing and use a WindowListener, like so:
import java.awt.event.*;
import javax.swing.*;
public class AskBeforeCloseTest extends JFrame {
    public AskBeforeCloseTest() {
        setDefaultCloseOperation(DO_NOTHING_ON_CLOSE);
        addWindowListener( new WindowAdapter() {
            public void windowClosing(WindowEvent e) {
                int ret = JOptionPane.showOptionDialog(
                        AskBeforeCloseTest.this,
                        "Do you want to quit?",
                        "Quit?",
                        JOptionPane.YES_NO_OPTION,
                        JOptionPane.QUESTION_MESSAGE,
                        null,
                        null,
                        null);
                if( ret == JOptionPane.YES_OPTION ) {
                    System.exit(0);
        getContentPane().add(new JLabel("Hello"));
        pack();
        setLocationRelativeTo(null);
    public static void main(String[] args) {
        new AskBeforeCloseTest().setVisible(true);
}