WindowEventDemo.java
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class WindowEventDemo extends JPanel
implements WindowListener,
WindowFocusListener,
WindowStateListener {
final static String newline = "\n";
final static String space = " ";
static JFrame frame;
JTextArea display;
public WindowEventDemo() {
super(new BorderLayout());
display = new JTextArea();
display.setEditable(false);
JScrollPane scrollPane = new JScrollPane(display);
scrollPane.setPreferredSize(new Dimension(500, 450));
add(scrollPane, BorderLayout.CENTER);
frame.addWindowListener(this);
frame.addWindowFocusListener(this);
frame.addWindowStateListener(this);
checkWM();
}
//Some window managers don't support all window states.
//For example, dtwm doesn't support true maximization,
//but mimics it by resizing the window to be the size
//of the screen. In this case the window does not fire
//the MAXIMIZED_ constants on the window's state listener.
//Microsoft Windows supports MAXIMIZED_BOTH, but not
//MAXIMIZED_VERT or MAXIMIZED_HORIZ.
public void checkWM() {
Toolkit tk = frame.getToolkit();
if (!(tk.isFrameStateSupported(Frame.ICONIFIED))) {
displayMessage(
"Your window manager doesn't support ICONIFIED.");
}
if (!(tk.isFrameStateSupported(Frame.MAXIMIZED_VERT))) {
displayMessage(
"Your window manager doesn't support MAXIMIZED_VERT.");
}
if (!(tk.isFrameStateSupported(Frame.MAXIMIZED_HORIZ))) {
displayMessage(
"Your window manager doesn't support MAXIMIZED_HORIZ.");
}
if (!(tk.isFrameStateSupported(Frame.MAXIMIZED_BOTH))) {
displayMessage(
"Your window manager doesn't support MAXIMIZED_BOTH.");
} else {
displayMessage(
"Your window manager supports MAXIMIZED_BOTH.");
}
}
public void windowClosing(WindowEvent e) {
displayMessage("WindowListener method called: windowClosing.");
//A pause so user can see the message before
//the window actually closes.
ActionListener task = new ActionListener() {
boolean alreadyDisposed = false;
public void actionPerformed(ActionEvent e) {
if (!alreadyDisposed) {
alreadyDisposed = true;
frame.dispose();
} else { //make sure the program exits
System.exit(0);
}
}
};
Timer timer = new Timer(500, task); //fire every half second
timer.setInitialDelay(2000); //first delay 2 seconds
timer.start();
}
public void windowClosed(WindowEvent e) {
//This will only be seen on standard output.
displayMessage("WindowListener method called: windowClosed.");
}
public void windowOpened(WindowEvent e) {
displayMessage("WindowListener method called: windowOpened.");
}
public void windowIconified(WindowEvent e) {
displayMessage("WindowListener method called: windowIconified.");
}
public void windowDeiconified(WindowEvent e) {
displayMessage("WindowListener method called: windowDeiconified.");
}
public void windowActivated(WindowEvent e) {
displayMessage("WindowListener method called: windowActivated.");
}
public void windowDeactivated(WindowEvent e) {
displayMessage("WindowListener method called: windowDeactivated.");
}
public void windowGainedFocus(WindowEvent e) {
displayMessage("WindowFocusListener method called: windowGainedFocus.");
}
public void windowLostFocus(WindowEvent e) {
displayMessage("WindowFocusListener method called: windowLostFocus.");
}
public void windowStateChanged(WindowEvent e) {
displayStateMessage(
"WindowStateListener method called: windowStateChanged.", e);
}
void displayMessage(String msg) {
display.append(msg + newline);
System.out.println(msg);
}
void displayStateMessage(String prefix, WindowEvent e) {
int state = e.getNewState();
int oldState = e.getOldState();
String msg = prefix
+ newline + space
+ "New state: "
+ convertStateToString(state)
+ newline + space
+ "Old state: "
+ convertStateToString(oldState);
display.append(msg + newline);
System.out.println(msg);
}
String convertStateToString(int state) {
if (state == Frame.NORMAL) {
return "NORMAL";
}
if ((state & Frame.ICONIFIED) != 0) {
return "ICONIFIED";
}
//MAXIMIZED_BOTH is a concatenation of two bits, so
//we need to test for an exact match.
if ((state & Frame.MAXIMIZED_BOTH) == Frame.MAXIMIZED_BOTH) {
return "MAXIMIZED_BOTH";
}
if ((state & Frame.MAXIMIZED_VERT) != 0) {
return "MAXIMIZED_VERT";
}
if ((state & Frame.MAXIMIZED_HORIZ) != 0) {
return "MAXIMIZED_HORIZ";
}
return "UNKNOWN";
}
/**
* Create the GUI and show it. For thread safety,
* this method should be invoked from the
* event-dispatching thread.
*/
private static void createAndShowGUI() {
//Make sure we have nice window decorations.
JFrame.setDefaultLookAndFeelDecorated(true);
//Create and set up the window.
frame = new JFrame("WindowEventDemo");
frame.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
//Create and set up the content pane.
JComponent newContentPane = new WindowEventDemo();
newContentPane.setOpaque(true); //content panes must be opaque
frame.setContentPane(newContentPane);
//Display the window.
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
//Schedule a job for the event-dispatching thread:
//creating and showing this application's GUI.
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
}
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