我正在为一个类项目制作pong，我不知道如何使用键盘输入。我在网上看过很多指南，但我所做的一切都不管用。知道为什么它没有注册任何键盘输入吗？我很肯定我有所有正确的进口。

package pong2;

 import java.awt.color.*;
 import javax.swing.JFrame;
 import java.awt.Canvas;
 import java.awt.Color;
 import java.awt.Graphics;
 import java.awt.event.KeyEvent;
 import java.awt.event.KeyListener;
 import java.util.logging.Level;
 import java.util.logging.Logger;

 public class graphic extends Canvas implements KeyListener 
 {
         int y1 = 450;
         int y2 = 450;

         public static void main(String[] args) throws InterruptedException 
         {

jframe公司

JFrame frame = new JFrame("Pong");
                     Canvas canvas = new graphic();
                     canvas.setSize(1920,1080);
                     frame.add(canvas);
                     frame.setBackground(Color.BLACK);
                     frame.pack();
                     frame.setVisible(true);
                     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                     frame.addKeyListener(new KeyListener() );

                     frame.repaint();

         }

密钥侦听器

@Override
         public void  keyTyped(KeyEvent e) 
     {
             //System.out.println("Key Typed");
     }
         @Override
         public void keyPressed(KeyEvent e) 
     {
             if(e.getKeyCode() == KeyEvent.VK_DOWN); 
             {
                 //System.out.println("Key Pressed " + e.getKeyCode());
                 y2 = y2 - 10;
                 repaint();

             }       

             if(e.getKeyCode() == KeyEvent.VK_UP);
             {
                 y2 = y2 + 10;
                 repaint();
             }
     }
         @Override

          public void keyReleased(KeyEvent e) 
      {
                 //System.out.println("Key Released");
      }

乒乓板图形

public void paint(Graphics g) 
     {
             super.paint(g);

             //Background
             g.setColor(Color.BLACK);
             g.fillRect(0,0,1920,1080);

             //Goals
             g.setColor(Color.WHITE);
             g.fillRect(0,0,50,1080);
             g.fillRect(1870,0,50,1080);

             //Paddles
             g.fillRect(120,y1,20,150);
             g.fillRect(1790,y2,20,150);

             //Ball
             g.fillRect(950,525,20,20);
     }

 }