AWT Window Close Listener/Event

Question

I am sorry if this is a n00b question, but I have spent way too long for this once I create the Window listener, window event, and everything else, how do I specify what method to invoke? Here is my code:

private static void mw() {     Frame frm = new Frame("Hello Java");     WindowEvent we = new WindowEvent(frm, WindowEvent.WINDOW_CLOSED);     WindowListener wl = null;     wl.windowClosed(we);     frm.addWindowListener(wl);     TextField tf = new TextField(80);     frm.add(tf);     frm.pack();     frm.setVisible(true);  } 

I am trying to get a URL, and Download it, I have everything else worked out, I am just trying to get the window to close.

Answer 1

import java.awt.*; import java.awt.event.*; import javax.swing.*;  class FrameByeBye {      // The method we wish to call on exit.     public static void showDialog(Component c) {         JOptionPane.showMessageDialog(c, "Bye Bye!");     }      public static void main(String[] args) {         // creating/udpating Swing GUIs must be done on the EDT.         SwingUtilities.invokeLater(new Runnable() {             public void run() {                  final JFrame f = new JFrame("Say Bye Bye!");                 // Swing's default behavior for JFrames is to hide them.                 f.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);                 f.addWindowListener( new WindowAdapter() {                     @Override                     public void windowClosing(WindowEvent we) {                         showDialog(f);                         System.exit(0);                     }                 } );                 f.setSize(300,200);                 f.setLocationByPlatform(true);                 f.setVisible(true);              }         });     } } 

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Also look into Runtime.addShutdownHook(Thread) for any action that is vital to perform before shutting down.

AWT

Here is an AWT version of that code.

import java.awt.*; import java.awt.event.*;  class FrameByeBye {      // The method we wish to call on exit.     public static void showMessage() {         System.out.println("Bye Bye!");     }      public static void main(String[] args) {         Frame f = new Frame("Say Bye Bye!");         f.addWindowListener( new WindowAdapter() {             @Override             public void windowClosing(WindowEvent we) {                 showMessage();                 System.exit(0);             }         } );         f.setSize(300,200);         f.setLocationByPlatform(true);         f.setVisible(true);     } } 

Answer 2

This example shows how to use addWindowListener() with a WindowAdapter, a concrete implementation of the WindowListener interface. See also, How to Write Window Listeners.