This section provides 3 solutions and sample programs on how to close the main frame and terminate the application.
Problem: I have a frame window displayed on the screen and I want
to close the frame and terminate the application, when user invokes
the close command from the window's system menu, or clicks on the close icon
from the window's system icon list.
Solution 1: You can use the JFrame.setDefaultCloseOperation() method
to change the default behavior option of JFrame responding to the window
closing event. Select the EXIT_ON_CLOSE option will terminate the application
immediately. Of course, when the application is terminated, all frames
will be closed automatically. The following sample code, JFrameClose1.java,
shows you how to do this.
/**
* JFrameClose1.java
* Copyright (c) 2002 by Dr. Herong Yang, http://www.herongyang.com/
*/
import javax.swing.*;
public class JFrameClose1 {
public static void main(String[] a) {
JFrame f = new JFrame();
f.setTitle("Closing Frame with Default Close Operation");
f.setBounds(100,50,500,300);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setVisible(true);
}
}
Solution 2: You can extend JFrame class to have your own
frame class, so that you can override the default processWindowEvent() method
to terminate the application. Of course, calling System.exit(0) is the quickest
way to terminate an application. The following sample code, JFrameClose2.java,
shows you how to do this.
/**
* JFrameClose2.java
* Copyright (c) 2002 by Dr. Herong Yang, http://www.herongyang.com/
*/
import java.awt.event.*;
import javax.swing.*;
public class JFrameClose2 {
public static void main(String[] a) {
MyJFrame f = new MyJFrame();
f.setTitle("Closing Frame with Process Window Event");
f.setBounds(100,50,500,300);
f.setVisible(true);
}
static class MyJFrame extends JFrame {
protected void processWindowEvent(WindowEvent e) {
if (e.getID() == WindowEvent.WINDOW_CLOSING) {
System.exit(0);
}
}
}
}
Solution 3: You can create a new window event listener class and add
an object of this listener class to the JFrame object. In the new window event
listener, you can implement your owner version of windowClosing() handler method.
Of course, the quickest way to create a new window event listener class is to
extend the WindowAdapter class. The following sample code, JFrameClose3.java,
shows you how to do this.
/**
* JFrameClose3.java
* Copyright (c) 2002 by Dr. Herong Yang, http://www.herongyang.com/
*/
import java.awt.event.*;
import javax.swing.*;
public class JFrameClose3 {
public static void main(String[] a) {
JFrame f = new JFrame();
f.setTitle("Closing Frame with Window Listener");
f.setBounds(100,50,500,300);
f.addWindowListener(new MyWindowListener());
f.setVisible(true);
}
static class MyWindowListener extends WindowAdapter {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
}
}
Sample programs listed in this section have been tested with JDK 1.3.1, 1.4.1, 1.5.0 and 1.6.0.
