Importance of 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