Java Swing Tutorials - Herong's Tutorial Examples - v4.32, by Herong Yang
setAccelerator() - Setting Keyboard Accelerators on Menu Items
This section provides a tutorial example on how to use setAccelerator() method to associate accelerators to menu items. Accelerators allows user to interact with menu items using keys on keyboard.
Keyboard mnemonics allows users to invoke a menu item with a single key. But the menu contains that menu item must be popped up first.
For users to invoke a menu item without its menu popped up, we need to assign an accelerator, key combination, to that menu item with the setAccelerator() method. Here is how it works:
1. Assign difference accelerators, representing different key combinations, to different menu items.
2. Adding an action listener to each menu item.
3. When an accelerator, key combination, is pressed at any time, the menu item with the matching accelerator will fire an action event.
Here is an example program I wrote to test the setAccelerator() method:
/* JMenuItemSetAcceleratorTest.java * Copyright (c) 1997-2024 HerongYang.com. All Rights Reserved. */ import java.awt.event.*; import javax.swing.*; import javax.swing.event.*; public class JMenuItemSetAcceleratorTest implements ActionListener { JFrame myFrame = null; public static void main(String[] a) { (new JMenuItemSetAcceleratorTest()).test(); } private void test() { myFrame = new JFrame("Menu Item Accelerator Test"); myFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); myFrame.setBounds(50,50,250,150); myFrame.setContentPane(new JDesktopPane()); JMenuBar myMenuBar = new JMenuBar(); JMenu myMenu = getFileMenu(); myMenuBar.add(myMenu); myMenu = getColorMenu(); myMenuBar.add(myMenu); myMenu = getOptionMenu(); myMenuBar.add(myMenu); JMenuItem myItem = new JMenuItem("Help"); myItem.setMnemonic(KeyEvent.VK_H); myItem.setAccelerator( KeyStroke.getKeyStroke(KeyEvent.VK_P, ActionEvent.CTRL_MASK)); myItem.addActionListener(this); myMenuBar.add(myItem); myFrame.setJMenuBar(myMenuBar); myFrame.setVisible(true); } private JMenu getFileMenu() { JMenu myMenu = new JMenu("File"); JMenuItem myItem = new JMenuItem("Open"); myMenu.add(myItem); myItem = new JMenuItem("Close"); myMenu.add(myItem); myMenu.addSeparator(); myItem = new JMenuItem("Exit"); myMenu.add(myItem); return myMenu; } private JMenu getColorMenu() { JMenu myMenu = new JMenu("Color"); ButtonGroup myGroup = new ButtonGroup(); JRadioButtonMenuItem myItem = new JRadioButtonMenuItem("Red"); myItem.setSelected(true); myItem.setMnemonic(KeyEvent.VK_R); myItem.setAccelerator( KeyStroke.getKeyStroke(KeyEvent.VK_D, ActionEvent.CTRL_MASK)); myItem.addActionListener(this); myGroup.add(myItem); myMenu.add(myItem); myItem = new JRadioButtonMenuItem("Green"); myItem.setMnemonic(KeyEvent.VK_G); myItem.setAccelerator( KeyStroke.getKeyStroke(KeyEvent.VK_N, ActionEvent.CTRL_MASK)); myItem.addActionListener(this); myGroup.add(myItem); myMenu.add(myItem); myItem = new JRadioButtonMenuItem("Blue"); myItem.setMnemonic(KeyEvent.VK_B); myItem.setAccelerator( KeyStroke.getKeyStroke(KeyEvent.VK_E, ActionEvent.CTRL_MASK)); myItem.addActionListener(this); myGroup.add(myItem); myMenu.add(myItem); return myMenu; } private JMenu getOptionMenu() { JMenu myMenu = new JMenu("Option"); JMenuItem myItem = new JMenuItem("Sound"); myMenu.add(myItem); myItem = new JMenuItem("Auto save"); myMenu.add(myItem); return myMenu; } public void actionPerformed(ActionEvent e) { System.out.println("Item clicked: "+e.getActionCommand()); } }
If you run this example, you will see the frame window shows up with the menu bar like this:
Don't open the "Color" menu, and press <Ctrl>-d, <Ctrl>-n and <Ctrl>-e. Then repeat the test with the "Color" menu open. Also try <Ctrl>-p. You will see some messages printed on the Java console window:
Item clicked: Red Item clicked: Green Item clicked: Blue Item clicked: Red Item clicked: Green Item clicked: Blue Item clicked: Help
Interesting notes about this tutorial example:
Table of Contents
Introduction of Java Swing Package
Graphics Environment of the Local System
JCheckBox - Swing Check Box Class
JRadioButton - Swing Radio Button Class
JTextField - Swing Text Field Class
JComboBox - Swing Combo Box Class
►Menu Bar, Menus, Menu Items and Listeners
JMenuBar, JMenu, and JMenuItem Classes
JMenuBarTest.java - Menu Bar Test Program
JMenuTest.java - Menu Test Program
JMenuItemTest.java - Menu Item Test Program
JRadioButtonMenuItemTest.java - Radio Button Menu Item Test Program
JCheckBoxMenuItemTest.java - Check Box Menu Item Test Program
javax.swing.event.MenuListener - Menu Listener Interface
JMenuItemActionListenerTest.java - Menu Item Action Listener Test
Item Listener on Radio Button Menu Items
Item Listener on Check Box Menu Items
javax.swing.event.MenuKeyListener - Menu Key Listener Interface
setMnemonic() - Setting Keyboard Mnemonics on Menu Items
►setAccelerator() - Setting Keyboard Accelerators on Menu Items
setMnemonic() - Setting Keyboard Mnemonics on Menus
Creating Internal Frames inside the Main Frame
Layout of Components in a Container
JEditorPane - The Editor Pane Class
SwingWorker - The Background Task Worker
AWT (Abstract Windows Toolkit)