"please tell me an easy way how to draw the whole animation?!"
It may have to to do with how you're reading in the image. If you use ImageIO.read, it won't work. If you read it as an ImageIcon it seems to work
ImageIcon.getImage()
Image icon = new ImageIcon(new URL("http://i.stack.imgur.com/KSnus.gif")).getImage();
...
g.drawImage(icon, 20, 20, this);
Image with ImageIO
Image icon = ImageIO.read(new URL("http://i.stack.imgur.com/KSnus.gif"));
...
g.drawImage(icon, 20, 20, this);
