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

public class DoubleBuffer extends JPanel {
    BufferedImage offScreenImg;
    
    public static void main(String[] args) { 
	DoubleBuffer cbi = new DoubleBuffer(); 
	
	JFrame f = new JFrame("DoubleBuffer");
	f.setContentPane(cbi);
	f.setSize(200, 200);
	f.setVisible(true);
	f.addWindowListener(new WindowAdapter() {
		public void windowClosing(WindowEvent e) {
		    System.exit(0);
		}
	    });
	
	//createImage returns null if the Component does not appear on the screen.
	cbi.createImage();
	cbi.repaint();
    }
    
    public void createImage() {
	while (offScreenImg == null) {
	    //Create an off-creen image to use as a double buffer.
	    offScreenImg = (BufferedImage)createImage(100, 100);
	    System.out.println(offScreenImg);
	}
	Graphics2D g2 = offScreenImg.createGraphics();
	
	//Complete the image off-screeen.
	g2.setColor(Color.blue);
	g2.fillRect(0, 0, 100, 100);
	g2.drawImage(new ImageIcon("Dining.gif").getImage(), 20, 20, this);
    }
    
    public void paintComponent(Graphics g) {
	super.paintComponent(g);
	
	//Show the off-screen image.
	g.drawImage(offScreenImg, 50, 50, this);    
    }
    
}