Application wide keyboard shortcut - Java Swing

Question

I would like to create an application wide keyboard shortcut for a Java Swing application. Looping over all components and adding the shortcut on each, has focus related side effects, and seems like a brute force solution.

Anyone has a cleaner solution?

Answer 1

Install a custom KeyEventDispatcher. The KeyboardFocusManager class is also a good place for this functionality.

KeyEventDispatcher

Answer 2

For each window, use JComponent.registerKeyboardAction with a condition of WHEN_IN_FOCUSED_WINDOW. Alternatively use:

JComponent.getInputMap(WHEN_IN_FOCUSED_WINDOW).put(keyStroke, command);
JComponent.getActionMap().put(command,action);

as described in the registerKeyboardAction API docs.

Answer 3

For people wondering (like me) how to use KeyEventDispatcher, here is an example that I put together. It uses a HashMap for storing all global actions, because I don't like large if (key == ..) then .. else if (key == ..) then .. else if (key ==..) .. constructs.

/** map containing all global actions */
private HashMap<KeyStroke, Action> actionMap = new HashMap<KeyStroke, Action>();

/** call this somewhere in your GUI construction */
private void setup() {
  KeyStroke key1 = KeyStroke.getKeyStroke(KeyEvent.VK_A, KeyEvent.CTRL_DOWN_MASK);
  actionMap.put(key1, new AbstractAction("action1") {
    @Override
    public void actionPerformed(ActionEvent e) {
      System.out.println("Ctrl-A pressed: " + e);
    }
  });
  // add more actions..

  KeyboardFocusManager kfm = KeyboardFocusManager.getCurrentKeyboardFocusManager();
  kfm.addKeyEventDispatcher( new KeyEventDispatcher() {

    @Override
    public boolean dispatchKeyEvent(KeyEvent e) {
      KeyStroke keyStroke = KeyStroke.getKeyStrokeForEvent(e);
      if ( actionMap.containsKey(keyStroke) ) {
        final Action a = actionMap.get(keyStroke);
        final ActionEvent ae = new ActionEvent(e.getSource(), e.getID(), null );
        SwingUtilities.invokeLater( new Runnable() {
          @Override
          public void run() {
            a.actionPerformed(ae);
          }
        } ); 
        return true;
      }
      return false;
    }
  });
}

The use of SwingUtils.invokeLater() is maybe not necessary, but it is probably a good idea not to block the global event loop.

Answer 4

When you have a menu, you can add global keyboard shortcuts to menu items:

    JMenuItem item = new JMenuItem(action);
    KeyStroke key = KeyStroke.getKeyStroke(
        KeyEvent.VK_R, KeyEvent.CTRL_DOWN_MASK);
    item.setAccelerator(key);
    menu.add(item);

Answer 5

A little simplified example:

KeyboardFocusManager keyManager;

keyManager=KeyboardFocusManager.getCurrentKeyboardFocusManager();
keyManager.addKeyEventDispatcher(new KeyEventDispatcher() {

  @Override
  public boolean dispatchKeyEvent(KeyEvent e) {
    if(e.getID()==KeyEvent.KEY_PRESSED && e.getKeyCode()==27){
      System.out.println("Esc");
      return true;
    }
    return false;
  }

});

Answer 6

Use the following piece of code

ActionListener a=new ActionListener(){
   public void actionPerformed(ActionEvent ae)
   {
    // your code
   }
};
getRootPane().registerKeyboardAction(a,KeyStroke.getKeyStroke("ctrl D"),JComponent.WHEN_IN_FOCUSED_WINDOW);

Replace "ctrl D" with the shortcut you want.