JFrame 中的 Java 移动问题

Question

我编写了一个程序，其中 JFrame 中有一个绿色方 block ，您可以按“A”和“D”键左右移动(A=左，D=右)。但是当我运行程序时，按下 A/D 键时方 block 不会移动。我尝试检查我的代码是否有错误，但找不到任何错误。如果你能告诉我我的代码哪里错了那就太棒了!!

import java.awt.event.*;
import java.awt.*;
import java.util.Scanner;
import javax.swing.*;

    public class four extends JPanel implements ActionListener,KeyListener {
    private static final long serialVersionUID = 1L;  
    static int x=0, y=0;  
    static int x1=0, y1=0;  
    static int width=500,height=600;        
    static JFrame f;  
    boolean left, right;  
    boolean playGame = true;

public void paintComponent (Graphics g){        
    g.setColor(Color.black);
    g.drawRect(x,100,700,100);
    g.drawRect(x,200,700,100);
    g.drawRect(x,300,700,100);
    g.drawRect(x,400,700,100);
    g.drawRect(x,500,700,100);
    g.drawRect(x,600,700,100);
    g.drawRect(x,700,700,100);
    g.drawRect(100,100,100,700);
    g.drawRect(200,100,0,700);
    g.drawRect(300,100,0,700);
    g.drawRect(400,100,0,700);
    g.drawRect(500,100,0,700);
    g.drawRect(600,100,0,700);
    g.setColor(Color.green);
    g.fillRect(x1, y1, 100, 100);
}
public static void main(String[] args){  
    four q=new four();
    JFrame f=new JFrame("Connect 4");
    q.init(); 
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
    f.add(q);
    f.setSize(700,820);
    f.setVisible(true);
} 
public void init (){
    this.addKeyListener(this);  
    setFocusable(true);  

}
@Override
public void actionPerformed(ActionEvent e) {
    // TODO Auto-generated method stub

    if (left==true)             
    {
        x1=x1-100;
    }
    if (right==true)             
    {
        x1=x1+100;
    }
    f.repaint();
    System.out.println(x1);
    }

@Override
public void keyPressed(KeyEvent e) {
    // TODO Auto-generated method stub
    if (e.getKeyCode()==KeyEvent.VK_A){  
        left=true;
    }
    if (e.getKeyCode()==KeyEvent.VK_D){  
        left=true;
    }
}
@Override
public void keyReleased(KeyEvent e) {
    // TODO Auto-generated method stub
    if (e.getKeyCode()==KeyEvent.VK_A){  
        left=false;
    }
    if (e.getKeyCode()==KeyEvent.VK_D){  
        right=false;
    }
}
@Override
public void keyTyped(KeyEvent e) {
    // TODO Auto-generated method stub

}

Answer 1

1. 在执行任何自定义绘制之前调用 super.paintComponent
2. 在 KeyListener 上使用键绑定(bind) API，它解决了 KeyListener 所遇到的与焦点相关的问题。请参阅How to Use Key Bindings了解更多详情
3. 从事件调度线程的上下文中初始化 UI。请参阅Initial Threads了解更多详情
4. 什么在调用 actionPerformed 方法？我想你想仔细看看How to use Swing Timers