Ball bouncing off screen applet

Bouncing Ball

package bouncingball;

import java.awt.*;
import java.applet.*;
import java.util.Timer;
import java.util.TimerTask;


public class BouncingBallApplet extends Applet {
	
/**
	 * 
	 */
	private static final long serialVersionUID = 1L;

Timer timer;
    
    int [] ball={10,10};
    int [] vel={2,5};
    int refreshrate = 150;
    int size = 200;
    int rect_left =5;
    int rect_right=size+rect_left;
    int rect_top=5;
    int rect_bottom=size+rect_top;
    
    
            
    
    
    
    public void init() {
        
    	setSize(300,300);
    	
        timer =new Timer();
        
       timer.schedule(new TimerTask(){
            
       
               
                public void run() {
                  
                    
                    ballBounce();
                    repaint();
                }
        
       } , 0,refreshrate);}
               
    public void ballBounce(){
        
        ball[0]=ball[0]+vel[0];
                    ball[1]=ball[1]+vel[1];
        if(ball[0]<=rect_left)
        {vel[0]=-vel[0];}
        
        if(ball[0]>=rect_right-20)//makes the ball fit into the screen
        {vel[0]=-vel[0];}
        
        if(ball[1]<=rect_top)
        {vel[1]=-vel[1];}
        
        if(ball[1]>=rect_bottom-20)
        {vel[1]=-vel[1];}
        
       
    }
    

    public void paint(Graphics g){
        g.setColor(Color.black);
        g.drawRect(rect_left, rect_top, size, size);
        g.setColor(Color.BLUE);
        g.fillOval(ball[0], ball[1], 20, 20);
        
    }

}