Hello,

The following is a bouncing ball applet. When I do double buffering (variables, g1 and image), I still see the flickering . I would be grateful for any help.

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.lang.Thread;

public class Ball_Bounce extends JApplet implements Runnable
{
    private Thread blueBall, redBall;
    private boolean xUp, yUp, xUp1, yUp1;
    private int x, y, xDx, yDy;
    private final int MAX_X = 500, MAX_Y = 500;
    private boolean flag = true;
    private Graphics g1;
    private Image image;
    
    public void init()
    {
        xUp = false;
        yUp = false;
        xDx = 1;
        yDy = 1;
        image = createImage(500, 500);
        g1 = image.getGraphics(); 
        createBall();
             
    }
    
    public void createBall()
    {
        x = 300;
        y = 250;
     
        redBall = new Thread(this);
        redBall.start();
    } 
    
    public void paint( Graphics g )
    {
       super.paint( g );
       
       g1.setColor (Color.gray);
       g1.clearRect (0, 0, 500, 500);
       g1.setColor (Color.RED);
       g1.fillOval (x, y, 50, 50);
       g.drawImage(image,0,0,this); 
           
              
    }
    
   
    public void run()
    {
      while ( flag == true ) 
      { 
       try 
        {
         
           redBall.sleep(10);
        }
        catch ( InterruptedException exception ) 
        {
           System.err.println( exception.toString() );
        }

       if ( y <= 0 ) {
           yUp = true;
           yDy = ( int ) ( Math.random() * 5 + 2 );
        }

        else if ( y >= MAX_Y - 50 ) {
           yDy = ( int ) ( Math.random() * 5 + 2 );
           yUp = false;
        }

        if ( x <= 0 ) {
           xUp = true;
           xDx = ( int ) ( Math.random() * 5 + 2 );
        }

        else if ( x >= MAX_X - 50 ) {
           xUp = false;
           xDx = ( int ) ( Math.random() * 5 + 2 );
        }
        
      
        if ( xUp == true )
           x += xDx;
        else
           x -= xDx;

        if ( yUp == true )
           y += yDy;
        else
           y -= yDy;
        
        repaint();
     }

  } 
  

 
}

Thank you!

Swing classes use double buffering. I you use a JPanel class, override the paintComponent method for your drawing and add that to the applet, the flickering could go away.

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