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

public class Window extends JFrame {
    
    public Window()
    {
        super("螃蟹过街");
        setIconImage(Toolkit.getDefaultToolkit().createImage("game/icon.png"));
        setSize(700,400);
        init();
        
        setLocation((Toolkit.getDefaultToolkit().getScreenSize().width-700)/2,(Toolkit.getDefaultToolkit().getScreenSize().height-400)/2);
        setVisible(true);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
    
    public void init()
    {
        Container rongqi=getContentPane();
        
    }
    
    public void paint(Graphics g)
    {
        Color c1=new Color(255,0,0,100);
        g.setColor(c1);
        g.setFont(new Font("",Font.BOLD,30));
        new Load_line(g).start();
        g.drawRect(200, 200, 100, 100);  //画矩形
        g.fillRect(220, 220, 60, 60);    //填充矩形
        
    }
    
    public static void main(String[] args)
    {
        new Window();
    }
}
--------------

import java.awt.Graphics;

public class Load_line extends Thread {
    Graphics q2;
    public Load_line(Graphics q1)
    {
        q2=q1;
    }
    
    public void run()
    {
        for(int i=40;i<300;i+=4)
        {
            q2.drawLine(20, i, 300, i);

            try 
            {
                sleep(300);
            } 
            catch (InterruptedException e) 
            {    
                e.printStackTrace();
            }    
        }
    }

}