Java GUI画圆。详解编程语言

package ydj; 
 
import java.awt.*; 
 
import javax.swing.*; 
 
public class huayuan extends JFrame  
{ 
    public huayuan() 
    { 
        mianban mb=new mianban(); 
        Container content=getContentPane(); 
        this.setVisible(true); 
        this.setSize(400, 400); 
        content.add(mb); 
        mb.setBackground(Color.WHITE); 
        mb.setForeground(Color.GREEN); 
    } 
    class mianban extends JPanel 
    { 
        public void paint(Graphics g) 
        { 
            super.paint(g); 
            g.drawOval(500,100,100,100);        //第一层 
            g.drawOval(300,200,100,100);        //第二层第一个 
            g.drawOval(700,200,100,100);        //弟二层第二个 
            g.drawOval(150,300,100,100);        //第三层第一个 
            g.drawOval(400,300,100,100);        //第三层第二个 
            g.drawOval(550,300,100,100);        //第三层第三个 
            g.drawOval(800,300,100,100);        //第三层第四个 
            g.drawOval(250,400,100,100);        //第三层第一个 
            g.drawLine(510,175,390,225); 
            g.drawLine(600,150,715,215); 
            g.drawLine(310,275,150,300); 
            //g.drawLine(300,200,400,300); 
             
             
            
        } 
    } 
    public static void main(String args[]) 
    { 
        huayuan c=new huayuan(); 
    } 
}