在JApplet中如何实现刷新？？

Question

import javax.swing.*;
import java.awt.*;public class EllipseDemo1 extends JApplet implements Runnable{        int radiu=0;
        int inc=10; public void paint(Graphics g){
super.paint(g);
 int width =getWidth();
int height=getHeight();
System.out.println("hello");
setBackground(Color.blue);
g.setColor(Color.green);
int x =(int)(width/2-radiu/2);
int y =(int)(height/2-radiu/2);
g.fillOval(x,y,radiu,radiu);
}
public void run(){
while(true){
radiu+=inc;
try{
  Thread.sleep(1000);
}catch(InterruptedException e)
{
System.out.println(e.getMessage());
}
                                              //update(getGraphics());
repaint();
      if (radiu==100)
break;
}

}
public void init(){
EllipseDemo1 demo=new EllipseDemo1();
Thread t =new Thread(demo);
t.start();
}

}我想实现画一个圆球让它的半径不断增大，可是不能刷新啊，用update(Graphics g)又不对，这是怎么回事？

Answer 1

import javax.swing.*;
import java.awt.*;public class EllipseDemo1 extends JApplet implements Runnable {
int radiu=0;
        int inc=10;
public void init(){
Thread t =new Thread(this);
t.start();
}
public void run(){
while(true){
radiu+=inc;
if (radiu==100)
break;
repaint();
try{
  Thread.sleep(1000);
}catch(InterruptedException e)
{
System.out.println(e.getMessage());
}
                                              //update(getGraphics());
}

}
public void paint(Graphics g){
super.paint(g);
  int width =getWidth();
int height=getHeight();
setBackground(Color.blue);
g.setColor(Color.green);
int x =(int)(width/2-radiu/2);
int y =(int)(height/2-radiu/2);
g.fillOval(x,y,radiu,radiu);
}

}
试试

Answer 2

import javax.swing.*;
import java.awt.*;public class EllipseDemo1 extends JApplet{
int radiu=0;
        int inc=10;
public void init(){
this.getContentPane().add(new Ell());
this.setVisible(true);
}
private class Ell extends JPanel implements Runnable{
public Ell()
{
setBackground(Color.blue);
Thread t =new Thread(this);
t.start();
}
public void run(){
while(true){
radiu+=inc;
if (radiu==100)
break;
repaint();
try{Thread.sleep(1000);}catch(InterruptedException e){System.out.println(e.getMessage());}
}
                                            
}
public void paint(Graphics g){
super.paint(g);
g.setColor(Color.green);
int x =(int)(getHeight()/2-radiu/2);
int y =(int)(getWidth()/2-radiu/2);
g.fillOval(x,y,radiu,radiu);
}
}
}

Answer 3

use following method to test:
moveall();repaint()