Shortcut key for jButton without using alt key

Question

In SWT you can give any button a shortcut key simply by adding & in front of the letter in the button label. For example, if my button label is &Play, I can activate the button by hitting letter p on the keyboard.

In Swing, you can add a shortcut key using the mnemonic property. However, you need to hit alt+p to activate the button. This is really most appropriate for menu shortcuts. I want to activate the button with a letter press and no alt modifier.

I've seen this post on how to do it, but it seems absurdly complicated. Is there an easier way to do this?

http://linuxjavaprogrammer.blogspot.com/2008/01/java-swing-jbutton-keyboard-shortcuts.html

Update: After @camickr suggestion, I ended up using this code. I couldn't find any clear and simple example online, so hopefully this will help people out.

// play is a jButton but can be any component in the window
play.getInputMap(play.WHEN_IN_FOCUSED_WINDOW).put(KeyStroke.getKeyStroke(KeyEvent.VK_P, 0), "play");
play.getActionMap().put("play", new AbstractAction() {
public void actionPerformed(ActionEvent e) {
  playActionPerformed(e);  // some function
}
});

Answer 1

Yes, Swing was designed to use Key Bindings. So instead of adding an ActionListener to the button you add an Action. Then that Action can be shared by the button or a menu item. You can also assign any number of KeyStrokes to invoke the Action by using the KeyBindings. The tutorial also has a section on Actions which explains why using an Action is beneficial.

JComponent has a registerKeyboardAction(...) method which basically does the InputMap/ActionMap bindings for you, but it also has to wrap the ActionListener in a wrapper Action so its preferrable for you to do you own bindings.

Answer 2

Further to camickr's answer, I am now using a little utility function like this:

public static void clickOnKey(
    final AbstractButton button, String actionName, int key )
{
    button.getInputMap( JButton.WHEN_IN_FOCUSED_WINDOW )
        .put( KeyStroke.getKeyStroke( key, 0 ), actionName );

    button.getActionMap().put( actionName, new AbstractAction()
    {
        @Override
        public void actionPerformed( ActionEvent e )
        {
            button.doClick();
        }
    } );
}

Now to set the keyboard shortcut for a button I just do:

clickOnKey( playButton, "play", KeyEvent.VK_P );