Programming Tutorials

Sample program to demonstrate the use of ActionListener

By: Ramlak in Java Tutorials on 2007-08-09  

This Java samples program demonstrates the use of ActionListener event handler. Action listeners are probably the easiest - and most common - event handlers to implement. You implement an action listener to define what should be done when an user performs certain operation.

This is a simple program which displays how many number of times a button is clicked by the user. First, here is the code that sets up the TextField , button and numClicks variable:

public class AL extends Frame implements WindowListener,ActionListener {
TextField text = new TextField(20);
Button b;
private int numClicks = 0;

In the above example, the event handler class is AL which implements ActionListener.

We would like to handle the button-click event, so we add an action listener to the button b as below:

b = new Button("Click me");
b.addActionListener(this); 

In the above code, Button b is a component upon which an instance of event handler class AL is registered.

Now, we want to display the text as to how many number of times a user clicked button. We can do this by writing the code as below:

public void actionPerformed(ActionEvent e) {
	 numClicks++;
	 text.setText("Button Clicked " + numClicks + " times");

The complete source code for the even handler is given below:

import java.awt.*;
import java.awt.event.*;

public class AL extends Frame implements WindowListener,ActionListener {
	TextField text = new TextField(20);
	Button b;
	private int numClicks = 0;

	public static void main(String[] args) {
		AL myWindow = new AL("My first window");
		myWindow.setSize(350,100);
		myWindow.setVisible(true);
	}

	public AL(String title) {

		super(title);
		setLayout(new FlowLayout());
		addWindowListener(this);
		b = new Button("Click me");
		add(b);
		add(text);
		b.addActionListener(this);
	}

	public void actionPerformed(ActionEvent e) {
		numClicks++;
		text.setText("Button Clicked " + numClicks + " times");
	}

	public void windowClosing(WindowEvent e) {
		dispose();
		System.exit(0);
	}

	public void windowOpened(WindowEvent e) {}
	public void windowActivated(WindowEvent e) {}
	public void windowIconified(WindowEvent e) {}
	public void windowDeiconified(WindowEvent e) {}
	public void windowDeactivated(WindowEvent e) {}
	public void windowClosed(WindowEvent e) {}

}