移动小圆圈

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

class TouChaCol{
    int x = 70;
    int y = 70;
    
    public static void main(String [] args){
        TouChaCol ch = new TouChaCol();
        ch.go();
    }
    
    class Panel extends JPanel{
        public void paintComponent(Graphics g){
            g.setColor(Color.white);
            g.fillRect(0, 0, this.getWidth(), this.getHeight());
            g.setColor(Color.orange);
            g.fillOval(x, y, 40, 40);
        }
    }
    
    public void go(){
        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        Panel panel = new Panel();
        frame.getContentPane().add(panel);
        
        frame.setSize(700,700);
        frame.setVisible(true);
        for(int i=0;i<300;i++){
            x++;
            y++;
            
            panel.repaint();
            try{
                Thread.sleep(50);
            }catch(Exception ex){
            }
        }
        
    }
}

用到内部类，内部类可直接使用到外部类的实例变量