java - 按键不起作用

Question

这个问题已经有答案了:

How to use Key Bindings instead of Key Listeners (4 个回答)

已关闭 8 年前。

 class Card31 extends JPanel implements KeyListener, MouseListener {
     public Card31() {
         addKeyListener(this);
         addMouseListener(this);
         x1 = 700;

     }

     public void keyPressed(KeyEvent e) {

     }

     public void keyReleased(KeyEvent e)

     {

     }

     public void keyTyped(KeyEvent e)

     {

         key = e.getKeyCode();
         if (key == KeyEvent.VK_RIGHT)
             x1 += 10;
         else if (key == KeyEvent.VK_LEFT)
             x1 -= 10;
         repaint();
     }
     public void mouseEntered(MouseEvent e) {
         requestFocus();
     }

     public void mouseExited(MouseEvent e) {}
     public void mousePressed(MouseEvent e) {}
     public void mouseReleased(MouseEvent e) {}

     public void mouseClicked(MouseEvent e) {

     }
     public void mouseClicked(MouseEvent e) {

     }
     public void paintComponent(Graphics g) {
         super.paintComponent(g);
         court2 = Toolkit.getDefaultToolkit().getImage("court2.jpg");
         bhoop = Toolkit.getDefaultToolkit().getImage("bhoop2.png");
         balla = Toolkit.getDefaultToolkit().getImage("balla.png");
         ballc = Toolkit.getDefaultToolkit().getImage("ballc.png");
         balld = Toolkit.getDefaultToolkit().getImage("balld.png");
         balle = Toolkit.getDefaultToolkit().getImage("balle.png");
         ballf = Toolkit.getDefaultToolkit().getImage("ballf.png");
         balli = Toolkit.getDefaultToolkit().getImage("balli.png");
         balll = Toolkit.getDefaultToolkit().getImage("balll.png");
         balln = Toolkit.getDefaultToolkit().getImage("balln.png");
         ballo = Toolkit.getDefaultToolkit().getImage("ballo.png");
         ballr = Toolkit.getDefaultToolkit().getImage("ballr.png");
         balls = Toolkit.getDefaultToolkit().getImage("balls.png");
         ballt = Toolkit.getDefaultToolkit().getImage("ballt.png");
         ballu = Toolkit.getDefaultToolkit().getImage("ballu.png");
         bally = Toolkit.getDefaultToolkit().getImage("bally.png");
         g.drawImage(court2, 0, 0, 1600, 1000, this);
         g.drawImage(ballo, 130, 100, 110, 110, this);
         g.drawImage(ballc, 280, 100, 110, 110, this);
         g.drawImage(balln, 430, 100, 110, 110, this);
         g.drawImage(balld, 580, 100, 110, 110, this);
         g.drawImage(balle, 730, 100, 110, 110, this);
         g.drawImage(ballc, 880, 100, 110, 110, this);
         g.drawImage(balle, 1030, 100, 110, 110, this);
         g.drawImage(ballu, 1180, 100, 110, 110, this);
         g.drawImage(bally, 1330, 100, 110, 110, this);
         g.drawRect(30, 30, 80, 20);
         Font plainfont = new Font("Serif", Font.BOLD, 20);
         g.setFont(plainfont);
         g.setColor(Color.BLACK);
         g.drawString("Score: " + score1, 30, 30);
         g.fillRect(700, 800, 200, 20);
         g.drawImage(bhoop, x1, 500, 150, 150, this);

         g.drawString(msg1, 200, 200);
         System.out.println("x1" + x1);
     }
 }

上面我附上了部分代码，一个嵌套类。 X1 是一个全局变量，在构造函数中初始化。用于移动 Iamge bhoop 的 KeyPressed 不起作用。我已经检查了所有代码以确保其正确，但无论如何图像都不会移动。请帮我解决这个问题。我非常感谢您的帮助<3.

Answer 1

已注册KeyListener 的组件必须具有焦点，KeyListener 才能触发。在组件上调用 requestFocus 以请求组件获得焦点，或者更好地使用 KeyBindings