Duke Pt avail. 2nd time askin, (Flicker-free background) Simple Animation

Question

2nd time askin, since didn't get sufficient help. Duke Pts available! I am trying to create simple animation on a solid constant background. I used double buffering for moving the object and it works fine. But the problem is with the background image. The image seems to flicker while the object is moving. Here's my code:
import java.awt.*;
import java.applet.Applet;
public class changed extends Applet implements Runnable{
Image buffer;
Graphics bufferg;
Thread main;
int x=0;
boolean flag=false;
public void init(){
setSize(500,500);
main=new Thread(this);
main.start();
buffer=createImage(getSize().width,getSize().height);
bufferg=buffer.getGraphics();
public void run(){
while(main!=null){
try     {
main.sleep(50);
catch(Exception e){}
repaint();
public void stop(){
if(main!=null){main.stop();}
public void paint(Graphics g){
update(g);
public void update(Graphics g){
Dimension d=getSize();
bufferg.setColor(getBackground());
bufferg.fillRect(0,0,d.width,d.height);
bufferg.setColor(Color.red);
Image img = getImage(getCodeBase(),"bliss.jpg");
if((x<500)&(!flag))
bufferg.fillRect(x+=5,10,25,25);
else
flag=true;
bufferg.fillRect(x-=5,10,25,25);
if(x==0)
flag=false;
g.drawImage(img,50,50,this);
g.drawImage(buffer,0,0,this);
Please help me with this minor problem. I think what's happening is that the background is been drawn over and over again. I don't know how to make it constant and flicker-free.

Answer 1

Possible 2 things:
1. You're reloading the image on each repaint:
Image img = getImage(getCodeBase(),"bliss.jpg");You shouldn't do that, you should just load it in init.
2. You're drawing the image with the non-buffer Graphics "g" instead of "bufferg." You should use bufferg and draw it before anything else.
I've modified the code for you, it should work but I can't test it because I don't have bliss.jpg. Let me know if it doesn't work.
Here's the modified code:
import java.awt.*;
import java.applet.Applet;
public class changed extends Applet implements Runnable {
     Image buffer,img;
     Graphics bufferg;
     Thread main;
     int x = 0;
     boolean flag = false;
     public void init() {
          setSize(500, 500);
          img = getImage(getCodeBase(), "bliss.jpg");
          main = new Thread(this);
          main.start();
          buffer = createImage(getSize().width, getSize().height);
          bufferg = buffer.getGraphics();
     public void run() {
          while (main != null) {
               try {
                    main.sleep(50);
               } catch (Exception e) {}
               repaint();
     public void stop() {
          if (main != null) {
               main.stop();
     public void paint(Graphics g) {
          update(g);
     public void update(Graphics g) {
          Dimension d = getSize();
          bufferg.drawImage(img, 50, 50, this);
          bufferg.setColor(getBackground());
          bufferg.fillRect(0, 0, d.width, d.height);
          bufferg.setColor(Color.red);
          if ((x < 500) & (!flag)) {
               bufferg.fillRect(x += 5, 10, 25, 25);
          } else {
               flag = true;
               bufferg.fillRect(x -= 5, 10, 25, 25);
               if (x == 0)
                    flag = false;
          g.drawImage(buffer, 0, 0, this);
}