KeyListener 类在游戏重置后变得无响应

Question

我正在用 java 编写一个简单的蛇应用程序我有一个包含游戏的 gamePanel 并将其添加到 JFrame Window 类中，当我第一次启动游戏时，keylistener 工作正常但是当游戏丢失时（按下按钮时，游戏会自行重置，但按键侦听器变得无响应），我看不出它应该变得无响应的任何原因，我没有对它做任何事情

class Window extends JFrame {

    private static final long serialVersionUID = -2542001418764869760L;
    private final ButtonPanel buttonPanel;
    private GamePanel gamePanel;
    private ThreadsController c;

    // now size of the game can change only by modifiying this width and height

    public JFrame getFrame() {
        return this;
    }

    public JPanel getGamePanel() {
        return gamePanel;
    }

    public JPanel getButtonPanel() {
        return buttonPanel;
    }

    public Window() throws FileNotFoundException {

        this.setTitle("Snake");
        this.setSize(300, 300);
        this.setVisible(true);
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setLocationRelativeTo(null);

        gamePanel = new GamePanel();
        this.buttonPanel = new ButtonPanel(this, c);

        this.add(new TopPanel(), BorderLayout.NORTH);

        this.add(gamePanel, BorderLayout.CENTER);
        this.add(buttonPanel, BorderLayout.SOUTH);
        this.setVisible(true);
        c = new ThreadsController(gamePanel.getSnakeDepartPosition());
        this.buttonPanel.getExit().addActionListener(
                new ButtonActionListener(this, c));
        this.buttonPanel.getNewGame().addActionListener(
                new ButtonActionListener(this, c));

        c.start();
        this.addKeyListener(new KeyboardListener());
        this.setFocusable(true);
    }

    private class KeyboardListener extends KeyAdapter {

        public void keyPressed(KeyEvent e) {
            switch (e.getKeyCode()) {
            case KeyEvent.VK_RIGHT:
                // if it's not the opposite direction
                if (ThreadsController.directionSnake != Directions.LEFT)
                    ThreadsController.directionSnake = Directions.RIGHT;
                break;
            case KeyEvent.VK_UP:
                if (ThreadsController.directionSnake != Directions.BOTTOM)
                    ThreadsController.directionSnake = Directions.TOP;
                break;

            case KeyEvent.VK_LEFT:
                if (ThreadsController.directionSnake != Directions.RIGHT)
                    ThreadsController.directionSnake = Directions.LEFT;
                break;

            case KeyEvent.VK_DOWN:
                if (ThreadsController.directionSnake != Directions.TOP)
                    ThreadsController.directionSnake = Directions.BOTTOM;
                break;

            default:
                break;
            }
        }    
    }

}


here is the action listener

    public class ButtonActionListener implements ActionListener {

    private Window frame;
    private ThreadsController t;

    public ButtonActionListener(Window frame, ThreadsController t) {
        this.frame = frame;
        this.t = t;
    }

    @Override
    public void actionPerformed(ActionEvent clickedButton) {
        // TODO Auto-generated method stub
        /*
         * t.setAlive(false);
         * 
         * frame.getContentPane().remove(frame.getGamePanel());
         * 
         * 
         * 
         * frame.add(gamePanel, BorderLayout.CENTER); frame.setVisible(true);
         */GamePanel gamePanel = new GamePanel();
        gamePanel.addKeyListener(new KeyboardListenner());
        frame.add(gamePanel, BorderLayout.CENTER);
        frame.setVisible(true);
        t = new ThreadsController(new Tuple(10, 10));
        t.start();    
    }    
}

Answer 1

KeyEvents 仅针对具有焦点的组件生成。

当您单击按钮时，按钮现在的焦点不是您的“GamePanel”。你需要使用：

gamePanel.requestFocusInWindow();

在框架可见之后。

但是，这并不能解决问题，因为您不能只将新的“GamePanel”添加到框架中，因为您的内容窗格现在将包含两个 GamePanel。如果组件添加到框架的顺序相反，Swing 将绘制组件。因此，您将首先绘制新的 GamePanel，然后将旧的 GamePanel 绘制在顶部。因此，您需要在添加新的 GamePanel 之前移除旧的 GamePanel。

或者，如果您想重置游戏，更好的方法是在您的 GamePanel 中有一个“重置”方法来重置游戏。不要k