How to use Key Bindings instead of Key Listeners

Question

I\'m using KeyListeners in my code (game or otherwise) as the way for my on-screen objects to react to user key input. Here is my code:

public class MyGame e         


        

Answer 1

Here is an example of how to get key bindings working.

(Inside JFrame subclass using extends, which is called by the constructor)

// Create key bindings for controls
private void createKeyBindings(JPanel p) {
    InputMap im = p.getInputMap(JPanel.WHEN_IN_FOCUSED_WINDOW);
    ActionMap am = p.getActionMap();
    im.put(KeyStroke.getKeyStroke("W"), MoveAction.Action.MOVE_UP);
    im.put(KeyStroke.getKeyStroke("S"), MoveAction.Action.MOVE_DOWN);
    im.put(KeyStroke.getKeyStroke("A"), MoveAction.Action.MOVE_LEFT);
    im.put(KeyStroke.getKeyStroke("D"), MoveAction.Action.MOVE_RIGHT);
    am.put(MoveAction.Action.MOVE_UP, new MoveAction(this, MoveAction.Action.MOVE_UP));
    am.put(MoveAction.Action.MOVE_DOWN, new MoveAction(this, MoveAction.Action.MOVE_DOWN));
    am.put(MoveAction.Action.MOVE_LEFT, new MoveAction(this, MoveAction.Action.MOVE_LEFT));
    am.put(MoveAction.Action.MOVE_RIGHT, new MoveAction(this, MoveAction.Action.MOVE_RIGHT));
}

Separate class to handle those key bindings created above (where Window is the class that extends from JFrame)

// Handles the key bindings
class MoveAction extends AbstractAction {

    enum Action {
        MOVE_UP, MOVE_DOWN, MOVE_LEFT, MOVE_RIGHT;
    }


    private static final long serialVersionUID = /* Some ID */;

    Window window;
    Action action;

    public MoveAction(Window window, Action action) {
        this.window = window;
        this.action = action;
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        switch (action) {
        case MOVE_UP:
            /* ... */
            break;
        case MOVE_DOWN:
            /* ... */
            break;
        case MOVE_LEFT:
            /* ... */
            break;
        case MOVE_RIGHT:
            /* ... */
            break;
        }
    }
}