KeyListener 在 Java 摆动中没有响应？

Question

当我按下向上或向下键时，我正在尝试制作一些简单的游戏，我想移动我的矩形，但问题是 keylistener 不起作用..

我已经为名为“classKeyEvents”的keylistener事件制作了单独的class这是导致问题还是我将keylistener添加到容器的方式导致了问题

我的代码

import java.awt.Color;
import java.awt.Container;
import java.awt.Graphics;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class Pong extends JPanel
{
    static public JFrame frame = null;
    Container con  = null;

    public static int paddleX = 10, paddleY = 270, paddleWidth = 10, paddleHeight = 80;
    public static int upSpeed = 5;
    public static int downSpeed = 5;


    public void creatWindow()
    {
        frame = new JFrame();
        con = frame.getContentPane();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setBounds(200,50,900,600);
        frame.setVisible(true);

        con.add(this);
        con.setFocusable(true);
        con.addKeyListener(new classKeyEvents());

        Runnable ml = new mainLoop();
        Thread th = new Thread(ml);
        th.start();

    }


    protected void paintComponent(Graphics g)
    {
      super.paintComponent(g);
      g.setColor(Color.darkGray);
      g.fillRect(0, 0, getWidth(), getHeight());

      g.setColor(Color.YELLOW);
      g.drawRect(paddleX, paddleY, paddleWidth, paddleHeight);
      g.fillRect(paddleX, paddleY, paddleWidth, paddleHeight);
      System.out.println("-----");

    }

    class classKeyEvents  implements KeyListener
    {

        public void keyTyped(KeyEvent e) { }

        public void keyPressed(KeyEvent e)
        {
           if(e.getKeyCode() == KeyEvent.VK_KP_UP)
           {

               System.out.println("...");
               Pong.paddleY -= Pong.upSpeed;
               Pong.frame.repaint();
           }

           else if(e.getKeyCode() == KeyEvent.VK_KP_DOWN)
           {
               System.out.println("...");
               Pong.paddleY += Pong.downSpeed;
               Pong.frame.repaint();
           }
        }

        public void keyReleased(KeyEvent e)
        {

        }

    }

    class mainLoop implements Runnable
    {
        public void run() 
        {
            while(true)
            {

                try 
                {
                    Thread.sleep(100);
                }
                catch (InterruptedException ex) 
                {
                    Logger.getLogger(Pong.class.getName()).log(Level.SEVERE, null, ex);
                }

            }

        }

    }

    public static void main(String[] args) 
    {
      Pong p = new Pong();              
      p.creatWindow();

    }

}

有人请帮我找到解决这个问题的方法，这对我有很大帮助

Answer 1

我想我找到了可能导致您的问题的原因。

KeyEvent.VK_KP_UP 

是 KEYPAD 上的 KeyEvent，因此是“KP”。

利用

KeyEvent.VK_UP / KeyEvent.VK_DOWN

反而。