使用双缓冲消除闪烁现象

[java]代码库

import java.awt.*;
import java.awt.event.*;

import javax.swing.*;


public class TankClient  extends Frame {




	int x= 50, y=50;
	
	Image offScreenImage =null;
	
	
	
	public void paint(Graphics g) 
	{
		Color c=g.getColor();
		
        g.setColor(Color.RED);
        g.fillOval(x, y, 30, 30);
        g.setColor(c);


        y += 5;
        System.out.println("hello");
	}

	public void update(Graphics g) 
	{
           if(offScreenImage==null)
           {
        	   offScreenImage=this.createImage(800, 600);        	   
           }
           Graphics gOffScreen=offScreenImage.getGraphics();
           Color c=gOffScreen.getColor();
           gOffScreen.setColor(Color.GREEN);
           gOffScreen.fillRect(0, 0, 800, 600);
           gOffScreen.setColor(c);
           paint(gOffScreen);
           
           g.drawImage(offScreenImage, 0, 0, null);
           
	}
	public void lauchFram()
	{
		this.setLocation(400, 300);
		this.setSize(800,600);
		this.setTitle("TankWar");
		//匿名类
		this.addWindowListener(new WindowAdapter()
		{
			public void windowClosing(WindowEvent e) {

			       System.exit(0);
			}	
		});
		this.setResizable(false);	
		this.setBackground(Color.GREEN);
		setVisible(true);
		new Thread(new PaintThread()).start();
	}
	
	public static void main(String[] args) {
		TankClient tc=new TankClient();
		tc.lauchFram();

	}

	
	private class PaintThread implements Runnable
	{
		public void run()
		{
			while(true)
			{
				//调用paint
				repaint();
				try {
					Thread.sleep(20);
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
				
			}
		}
	}
}