java - repaint() 不在线程中工作

Question

我两周前才开始学习java，所以我对java还不太了解。我正在尝试让一个球在框架内弹跳或移动。但当我在线程中运行它时，它不会重新绘制/更新，但如果我使用 while 循环或计时器，它就可以正常工作，我不明白我做错了什么。这是线程版本:

public class Game {

    public static void main(String args[]){
        Thread t1 = new Thread(new Ball());
        Ball ball1 = new Ball();
        JFrame frame = new JFrame("Breakout");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setBackground(Color.WHITE);
        frame.setSize(1000, 1000);
        frame.setVisible(true);
        frame.add(ball1);
        t1.start();     
      }
    }    

    public class Ball extends JPanel implements Runnable{
     public int x = 5, y = 5;
     public int speedx = 5, speedy = 5;
     public int width = 30, height = 30;
     public void run() {            
         while (true){  
            try {                   
                Physics();
                repaint();
                Thread.sleep(10);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }               
            }           
        }

    public void paintComponent(Graphics g){
        super.paintComponent(g);
        g.setColor(Color.RED);
        g.fillOval(x, y, width, height);            
    } 

    public void Physics(){
        x += speedx;
        y += speedy;
        if(0 > x || x > 1000){
            speedx = -speedx;
        }
        if(0 > y || y > 1000){
            speedy = -speedy;
        }       
    }
}

Answer 1

您正在使用两个不同的 Ball 对象:

       Thread t1 = new Thread(new Ball());


       Ball ball1 = new Ball();

更改顺序:

       Ball ball1 = new Ball();
       Thread t1 = new Thread(ball1);