The basics of Java drawing: Draw a circle

/**
* Basic principles of Java drawing: Draw a circle
* @author TFQ
* @date 2011-08-27
*/

Import javax.swing.*;
Import java.awt.*;

public class Drawcicle extends jframe{

Mypanel Mp=null;

public static void Main (string[] args) {
Drawcicle dc=new drawcicle ();
}

Public Drawcicle () {
MP =new Mypanel ();
This.add (MP);
This.setsize (300, 250);
This.setlocation (600, 300);
This.setdefaultcloseoperation (this. Exit_on_close);
This.setvisible (TRUE);
}
}

/**
 * A panel of paint and also displays
 * @author tfq
 *
 */
Class Mypanel extends jpanel{
&N Bsp
 /**
  * Overlay JPanel Paint () method
  * Graphics a brush class equivalent to drawing
  * Paint make up the call when the current panel is initialized, and the window changes to an hour is invoked,
  */
 public void Paint (Graphics g) {
  //invoke the parent class function to complete initialization
is also invoked when the window is maximized to minimize    //This sentence cannot be less
  super.paint (g);
  system.out.println ("piant () called!");
  //First draw a circle
  //g.drawoval (Ten, a);
  //draw a line
  // G.drawline (10, 20, 100, 20);
  //The first parameter represents the x-axis distance from the upper-left corner of the current form, the second parameter represents the y-axis distance from the upper-left corner of the current form, and the third fourth represents the width of the rectangle
  //g.drawrect (0, 0, 50, 60);
  //fills rectangular color
  g.setcolor (color.green);
  g.fillrect (0, 0,);
 }
}