java双缓冲绘图问题，急！在线等！

Question

我想画两个物体，一个从屏幕上往下移动，一个从左往右移动，可是闪的厉害~
你们帮我看看代码，我实现不了双缓冲！囧！！！
import java.awt.*;
import java.applet.*;
import javax.swing.*;
public class step1 extends Applet implements Runnable{
Thread thread1 ,thread2;
int y1=-100,y2=-50;
Image img[]=new Image[2];
public void init()
{
Image imageBuffer;                              //这里问题比较大
imageBuffer=createImage(getWidth(),getHeight());//  对吗你们帮我
Graphics imgobject=imageBuffer.getGraphics();
paint(imgobject);                                // 看看      setSize(800,600);
img[0]=getImage(getCodeBase(),"1.png");
img[1]=getImage(getCodeBase(),"2.png");
}
public step1()
{

setBackground(Color.WHITE);
thread1=new Thread(this);
thread2=new Thread(this);
thread1.start();
thread2.start();
}
public void paint(Graphics g)
{
//Graphics2D img2D=(Graphics2D)g;
if(thread1!=null)
{
g.drawImage(img[0], y1, 50, this);
}
if(thread2!=null)
{
g.drawImage(img[1],50,y2,115,y2+50,0,0,65,50,this);
}
}
public void run()
{
while(true)
{
if(Thread.currentThread()==thread1)
{
y1+=6;
if(y1>=400)
y1=-100;
repaint();
pause(100);
}
else if(Thread.currentThread()==thread2)
{
y2+=4;
if(y2>=400)
y2=-50;
repaint();
pause(120);
}
}
}
private void pause(int time)
{
try
{
Thread.sleep(time);
}catch(InterruptedException e){}
}}

Answer 1

public void paint(Graphics g) {
    Image imageBuffer = createImage(getWidth(), getHeight());
    Graphics imgobject = imageBuffer.getGraphics();
if(thread1!=null)
{
imgobject.drawImage(img[0], y1, 50, this);
}
if(thread2!=null)
{
imgobject.drawImage(img[1],50,y2,115,y2+50,0,0,65,50,this);
}    g.drawImage(0,0,imageBuffer);
}

Answer 2

public void paint(Graphics g) {
    Image imageBuffer = createImage(getWidth(), getHeight());
    Graphics imgobject = imageBuffer.getGraphics();
if(thread1!=null)
{
imgobject.drawImage(img[0], y1, 50, this);
}
if(thread2!=null)
{
imgobject.drawImage(img[1],50,y2,115,y2+50,0,0,65,50,this);
}    g.drawImage(imageBuffer,0,0,null);
} 
drawImage也不知道对不对。自己试吧。

Answer 3

我一阵乱改，居然不闪了，谁给我讲下为什么？
代码如下：
import java.awt.*;
import java.applet.*;
import javax.swing.*;
public class step1 extends Applet implements Runnable{
Thread thread1 ,thread2;
int y1=-100,y2=-50;
Image img[]=new Image[2];
public void init()
{

setSize(800,600);
img[0]=getImage(getCodeBase(),"plane2.png");
img[1]=getImage(getCodeBase(),"boss.png");
}
public step1()
{

setBackground(Color.WHITE);
thread1=new Thread(this);
thread2=new Thread(this);
thread1.start();
thread2.start();
}
public void update(Graphics g)   //添了个这个方法
{
Image imageBuffer;
imageBuffer=createImage(getWidth(),getHeight());
Graphics imgobject=imageBuffer.getGraphics();
paint(imgobject);
g.drawImage(imageBuffer,0,0,null);//虽然不闪了，可是我还是不懂，谁给我讲讲
}
public void paint(Graphics g)
{

if(thread1!=null)
{
g.drawImage(img[0], y1, 50, this);
}
if(thread2!=null)
{
g.drawImage(img[1],50,y2,115,y2+50,0,0,65,50,this);
}

}
public void run()
{
while(true)
{
if(Thread.currentThread()==thread1)
{
y1+=6;
if(y1>=400)
y1=-100;
repaint();
pause(100);
}
else if(Thread.currentThread()==thread2)
{
y2+=4;
if(y2>=400)
y2=-50;
repaint();
pause(120);
}
}
}
private void pause(int time)
{
try
{
Thread.sleep(time);
}catch(InterruptedException e){}
}}