java - KeyListener 在 Java swing 中没有响应？

Question

我正在尝试制作一些简单的游戏，当我按下向上键或向下键时我想移动我的矩形，但问题是按键监听器不起作用..

我为名为“classKeyEvents”的按键监听器事件创建了单独的类，这是导致问题的原因还是我将按键监听器添加到容器的方式导致了问题

My Code

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();

    }

}

请有人帮我找到这个问题的解决方案，这对我有很大帮助

Answer 1

我想我找到了可能导致您出现问题的原因。

KeyEvent.VK_KP_UP 

是键盘上的按键事件，因此是“KP”。

使用

KeyEvent.VK_UP / KeyEvent.VK_DOWN

相反。