Swing アプリケーションでキー リスナーの代わりにキー バインディングを使用する理由

myComponent.getInputMap().put("userInput", "myAction");
myComponent.getActionMap().put("myAction", action);

import javax.swing.*;

public class MyGame extends JFrame {

    private static final String MOVE_UP = "move up";
    private static final String MOVE_DOWN = "move down";
    private static final String FIRE = "move fire";

    static JLabel obj1 = new JLabel();
    static JLabel obj2 = new JLabel();

    public MyGame() {

        obj1.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW)
                .put(KeyStroke.getKeyStroke("UP"), MOVE_UP);
        obj1.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW)
                .put(KeyStroke.getKeyStroke("DOWN"), MOVE_DOWN);
        obj1.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW)
                .put(KeyStroke.getKeyStroke("control CONTROL"), FIRE);

        obj1.getActionMap().put(MOVE_UP, new MoveAction(1, 1));
        obj1.getActionMap().put(MOVE_DOWN, new MoveAction(2, 1));
        obj1.getActionMap().put(FIRE, new FireAction(1));

        obj2.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW)
                .put(KeyStroke.getKeyStroke("W"), MOVE_UP);
        obj2.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW)
                .put(KeyStroke.getKeyStroke("S"), MOVE_DOWN);
        obj2.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW)
                .put(KeyStroke.getKeyStroke("T"), FIRE);

        obj2.getActionMap().put(MOVE_UP, new MoveAction(1, 2));
        obj2.getActionMap().put(MOVE_DOWN, new MoveAction(2, 2));
        obj2.getActionMap().put(FIRE, new FireAction(2));

        add(obj1);
        add(obj2);
    }

    static void rebindKey(KeyEvent ke, String oldKey) {

        obj1.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW)
                .remove(KeyStroke.getKeyStroke(oldKey));
        obj1.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW)
                .put(KeyStroke.getKeyStrokeForEvent(ke),
                        obj1.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW)
                                .get(KeyStroke.getKeyStroke(oldKey)));
    }

    public static void main(String[] args) {

        new MyGame();
    }

    private class MoveAction extends AbstractAction {

        int direction;
        int player;

        MoveAction(int direction, int player) {

            this.direction = direction;
            this.player = player;
        }

        @Override
        public void actionPerformed(ActionEvent e) {

            // Implement move action for the player.
        }
    }

    private class FireAction extends AbstractAction {

        int player;

        FireAction(int player) {

            this.player = player;
        }

        @Override
        public void actionPerformed(ActionEvent e) {

            // Implement fire action for the player.
        }
    }
}