How can we set the shortcut key to a JButton in Java?

In this article, we will learn to set the shortcut key to a JButton in Java. In Swing-based applications, we can implement the addition of keyboard shortcuts to buttons to enable quicker navigation by the user.

What is a JButton?

A JButton is a subclass of AbstractButton, and it can be used to add platform-independent buttons to a Java Swing application. When the button is pressed or clicked, a JButton can generate an ActionListener interface; it can also generate the MouseListener and KeyListener interfaces.

Setting the Shortcut Key for JButton

We can also set the shortcut keys for a JButton using the setMnemonic() method. The following is the step-by-step process to set the shortcut key to a JButton in Java:

Class Declaration and Imports

The javax.swing.* provides Swing components (JFrame, JButton, etc.) while the java.awt.* provides AWT classes (Color, layout managers), and the class extends JFrame to create a window.

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class JButtonTest extends JFrame {

Variables & Constructor Setup

It has a private JButton variable named button. The constructor sets the JFrame window titled "JButtonTest".

private JButton button;
public JButtonTest() {
    setTitle("JButtonTest");

Button Creation and Configuration

Creates a new JButton with the text "Click or press ALT-C". It then sets the mnemonic 'C' through the setMnemonic() method. It then adds the button to the center of the frame using BorderLayout.

button = new JButton("Click or press ALT-C");
button.setMnemonic('C');
add(button, BorderLayout.CENTER);

Action Listener

Adds an anonymous ActionListener to the button, and the listener will display a message dialog that says "Button clicked or pressed" once it's triggered.

button.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent evt) {
        JOptionPane.showMessageDialog(null, ("Button clicked or pressed"));
    }
});

Main Method

The main method launches the application by creating an object of JButtonTest.

public static void main(String args[]) throws Exception {
    new JButtonTest();
}

Example

Below is an example of setting the shortcut key to a JButton using the setMnemonic() method:

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class JButtonTest extends JFrame {
   private JButton button;
   public JButtonTest() {
      setTitle("JButtonTest");
      button = new JButton("Click or press ALT-C");
      button.setMnemonic('C');
      add(button, BorderLayout.CENTER);
      button.addActionListener(new ActionListener() {
         public void actionPerformed(ActionEvent evt) {
            JOptionPane.showMessageDialog(null, ("Button clicked or pressed"));
         }
      });
      setSize(475, 250);
      setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      setLocationRelativeTo(null);
      setVisible(true);
   }
   public static void main(String args[]) throws Exception {
      new JButtonTest();
   }

Output

In the above program, if we click or apply the shortcut key (Alt+C from the keyboard) on the JButton, a new popup window can be generated below: