Java GUI >> Basic Animation

gistfile1.java

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

import javax.swing.JPanel;
public class MyGUI
 {
        public int x=0;
	public int y=0;
   
       public static void main(String[] args)
       {
    	   MyGUI gui=new MyGUI();
    	   gui.play();
       }
       public void play()
       {
           JFrame frame=new JFrame();
           frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
           DrawPanel draw=new DrawPanel(x,y);
           //frame.getContentPane().add(draw); //same thing, eat nut.
           frame.add(draw);
           frame.setSize(500,500);
           frame.setVisible(true);
             for(int i=0;i<250;i++)
              {
                 draw.x++;
                 draw.y++;
                 draw.repaint();  //tells the panel to redraw itself so we can see the circle in new location
              
              //If you don't do try-catch thread, you only see the last position of circle on the screen when i=249
                 //That for loop run very fast so you can't see the movement
              //we'll use thread to slow it by 25 miliseconds each loop, so we can see the movement of the circle
              try{
               Thread.sleep(25);
                  }catch(Exception e)
                  {} 
         }
     }
 }


class DrawPanel extends JPanel{
	int x,y;
	public DrawPanel(int x,int y)
	{
		this.x=x;
		this.y=y;
		
	}
     public void paintComponent(Graphics g)
       {
        g.setColor(Color.WHITE);//try to comment out this
        g.fillRect(0,0,this.getWidth(),this.getHeight());// and this, it'll be fun!
        g.setColor(Color.GREEN);
        g.fillOval(x, y, 50,50);
       }
}