Java ActionListener in AWT

The Java Abstract Window Toolkit (AWT) is a GUI framework that provides a set of classes and methods for creating and managing user interfaces in Java applications. One of the most important components in AWT is the ActionListener interface. It is a key element for adding interactivity in Java applications by handling user actions. In this article, let us understand about the ActionListener interface in detail.

In Java AWT, the ActionListener interface is a part of the ‘java.awt.event’ package. When you click on a button, menu item, or a check box, the Java ActionListener is called. It is notified in reference to an ActionEvent. It only has one method, actionPerformed(). The principle of an ActionListener is to record and respond to user interactions with GUI components.

Method of ActionListener

// When we click on the registered component, it triggers automatically.
public void actionPerformed(ActionEvent e)

Syntax of an ActionListener

1. At first, implement the ActionListener interface in the class.

public class Example Implements ActionListener  

2. Configure the component with the Listener.

component.addActionListener(instance of the Listener class); 

3. Override the actionPerformed method as a response to the method call.

public void actionPerformed(ActionEvent e){  
           //Write the code here  
}  

Examples of AWT ActionListener

Given below are some examples that will help you to understand the workings of the ActionListener interface easily.

Example 1:

In this example, a simple ActionListener is implemented on a Button component. The text on the label is updated with the name entered in the TextField when the Button is clicked.

Java

// Java Program to implement
// AWT ActionListener
import java.awt.*;
import java.awt.event.*;

// Driver Class
public class Main {
      // main function
    public static void main(String[] args){

        // Create a frame
        Frame f = new Frame("AWT ActionListener Example");

          // Set the size
        f.setSize(400, 200);

          // Set the layout
        f.setLayout(null);

          // Make the frame visible
        f.setVisible(true);

          // Set the background color of the frame
        f.setBackground(Color.LIGHT_GRAY);

        // Create a button
        Button b = new Button("Click Me");

          // Set the positions
        b.setBounds(160, 100, 80, 40);

          // Add button to the frame
        f.add(b);

          // Set the background color of the button
        b.setBackground(Color.GREEN);

        // Create a text field
        TextField tf = new TextField();

          // Set the positions
        tf.setBounds(50, 50, 300, 30);

          // Add text field to the frame
        f.add(tf);

        // Create a label
        Label lb = new Label();

          // Set the positions
        lb.setBounds(100, 150, 300, 30);

          // Add label to the frame
        f.add(lb);

        // Add an action listener to the button
        b.addActionListener(new ActionListener() {

            // Override the actionPerformed() method
            public void actionPerformed(ActionEvent e){

                  // Update the text of the label
                lb.setText("Hey " + tf.getText() + "! "
                           + "Welcome to GeeksforGeeks!");
            }

        });
    }
}

Run the code using the following commands:

javac Main.java
java Main

Output:

ActionListener Example-1 GIF

Final Screen Output of the Example:

ActionListener Example-1 Image Output

Example 2:

In this example, when the “Order” button is clicked, the ActionListener calculates the total cost of selected food items and displays it in a message dialog.

Java

// Java Program to
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class Main implements ActionListener {
    JCheckBox cb1, cb2, cb3;

    Main(){

        // Create a frame
        Frame f = new Frame("AWT ActionListener Example");

        // Create a label
        Label l = new Label("Food Menu");

        // Set the positions
        l.setBounds(150, 50, 300, 20);

        // Create check boxes and set the positions
        cb1 = new JCheckBox("Pizza @ 100");
        cb1.setBounds(100, 100, 150, 20);
        cb2 = new JCheckBox("Burger @ 30");
        cb2.setBounds(100, 150, 150, 20);
        cb3 = new JCheckBox("Tea @ 10");
        cb3.setBounds(100, 200, 150, 20);

        // Create a button and set the positions
        Button b = new Button("Order");
        b.setBounds(100, 250, 80, 30);

        // Add action listener to the button
        b.addActionListener(this);

        // Add components to the frame
        f.add(l);
        f.add(cb1);
        f.add(cb2);
        f.add(cb3);
        f.add(b);

        // Set the size of the frame and make it visible
        f.setSize(400, 400);
        f.setLayout(null);
        f.setVisible(true);
    }

    // Override the actionPerformed() method
    public void actionPerformed(ActionEvent e){

        // Calculate the total amount and display it
        float amount = 0;
        String msg = "";
        if (cb1.isSelected()) {
            amount += 100;
            msg = "Pizza: 100\n";
        }
        if (cb2.isSelected()) {
            amount += 30;
            msg += "Burger: 30\n";
        }
        if (cb3.isSelected()) {
            amount += 10;
            msg += "Tea: 10\n";
        }
        msg += "-----------------\n";
        JOptionPane.showMessageDialog(
            null, msg + "Total: " + amount);
    }

    // Main method
    public static void main(String[] args) {
      new Main();
    }
}

Run the code using the following commands:

javac Main.java
java Main

Output:

Final Screen Output of the Example: