event

WindowListener demo

In this tutorial we will see how to use the WindowListener. This is particularly useful when you are working with a window application and you want to monitor the state of each window. With the WindowListener you can monitor a number of events. The opening or the closing of a window for instance. So, when a window opens or closes, the respective function will be executed, and consequently the code we want to be executed every time that specific event occurs.

In short, all you have to do in order to work with a WindowListener is:

  • Create a JFrame window
  • Create a new WindowListener and override the methods that correspond to the events you want to monitor, e.g windowOpened, windowClosing, windowClosed, windowIconified etc

Let’s see the code:

package com.javacodegeeks.snippets.desktop;

import java.awt.event.WindowEvent;
import java.awt.event.WindowListener;

import javax.swing.JFrame;

public class WindowListenerDemo {

    private static void showUI() {

  JFrame jFrame = new JFrame("Window Listener");

  WindowListener listener = new WindowListener() {

@Override

public void windowActivated(WindowEvent event) {

    System.out.println(event);

}

@Override

public void windowClosed(WindowEvent event) {

    System.out.println(event);

}

@Override

public void windowClosing(WindowEvent event) {

    System.out.println(event);

    System.exit(0);

}

@Override

public void windowDeactivated(WindowEvent event) {

    System.out.println(event);

}

@Override

public void windowDeiconified(WindowEvent event) {

    System.out.println(event);

}

@Override

public void windowIconified(WindowEvent event) {

    System.out.println(event);

}

@Override

public void windowOpened(WindowEvent event) {

    System.out.println(event);

}

  };

  jFrame.addWindowListener(listener);

  jFrame.setSize(500, 500);

  jFrame.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() {

@Override

public void run() {

    showUI(); 

}

  });
    }

}

 
This was an example on how to use a WindowListener.

Ilias Tsagklis

Ilias is a software developer turned online entrepreneur. He is co-founder and Executive Editor at Java Code Geeks.
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