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What is the importance of a WindowListener interface in Java?
The class which process the WindowEvent needs to be implemented this interface and an object of this class can be registered with a component by using addWindowListener() method.
Methods of WindowListener Interface
The WindowListener interface defines 7 methods for handling window events
- void windowActivated(WindowEvent we) − Invoked when a window is activated.
- void windowDeactivated(WindowEvent we) − Invoked when a window is deactivated.
- void windowOpened(WindowEvent we) − Invoked when a window is opened.
- void windowClosed(WindowEvent we) − Invoked when a window is closed.
- void windowClosing(WindowEvent we) − Invoked when a window is closing.
- void windowIconified(WindowEvent we) − Invoked when a window minimized.
- void windowDeiconfied(WindowEvent we) − Invoked when a window is restored.
Syntax
public interface WindowListener extends EventListener
Example
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class WindowListenerTest extends JFrame implements WindowListener {
JLabel l1,l2;
JTextField t1;
JPasswordField p1;
JButton b1;
public WindowListenerTest() {
super("WindowListener Test");
setLayout(new GridLayout(3,2));
l1 = new JLabel("Name");
l2 = new JLabel("Password");
t1 = new JTextField(10);
p1 = new JPasswordField(10);
b1 = new JButton("Send");
add(l1);
add(t1);
add(l2);
add(p1);
add(b1);
addWindowListener(this);
}
public static void main(String args[]) {
WindowListenerTest wlt = new WindowListenerTest();
wlt.setSize(375, 250);
wlt.setResizable(false);
wlt.setLocationRelativeTo(null);
wlt.setVisible(true);
}
public void windowClosing(WindowEvent we) {
this.setVisible(false);
System.exit(0);
}
public void windowActivated(WindowEvent we) {
}
public void windowDeactivated(WindowEvent we) {
}
public void windowOpened(WindowEvent we) {
}
public void windowClosed(WindowEvent we) {
}
public void windowIconified(WindowEvent we) {
}
public void windowDeiconified(WindowEvent we) {
}
}Output
Updated on: 30-Jun-2020
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