如何将 arguments 传递给 KeyBinding 中的 AbstractAction？

Question

I have the following keybindings:

    InputMap iMap = component.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW);
    ActionMap aMap = component.getActionMap();
    
    iMap.put(KeyStroke.getKeyStroke("shift LEFT"), "MOVE_LONG_LEFT");
    iMap.put(KeyStroke.getKeyStroke("LEFT"), "MOVE_LEFT");
    aMap.put("MOVE_LONG_LEFT", moveLeft);   // I WANT moveLeft TO RECEIVE 10 AS PARAMETER
    aMap.put("MOVE_LEFT", moveLeft);        // I WANT moveLeft TO RECEIVE 1 AS PARAMETER

I would want to add a parameter to moveLeft in the ActionMap, something like (pseudocode):

aMap.put("MOVE_LONG_LEFT", moveLeft, 10);
aMap.put("MOVE_LEFT", moveLeft, 1);

...

Action moveLeft = new AbstractAction(int steps) {
    @Override
    public void actionPerformed(ActionEvent e) {
        System.out.println("moved Left " + steps + " steps");
    }
};

Is it possible to pass arguments in KeyBindings?

Answer 1

How do I pass an arguments to an AbstractAction

Create your Action as an inner class then you can save the parameter as in instance variable of your class:

class MoveAction extends AbstractAction 
{
    private int steps;

    public MoveAction(int steps)
    {
        this.steps = steps;
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        System.out.println("moved Left " + steps + " steps");
    }
};

Then you use the class like:

aMap.put("MOVE_LONG_LEFT", new MoveAction(10)); 
aMap.put("MOVE_LEFT", new MoveAction(1));  

See; Motion Using the Keyboard . The MotionWithKeyBindings example demonstrates this approach.