Create a smiling and crying face alternet using Threading Mechenism

 import java.awt.*;  
 import java.applet.*;  
 /*  
  <applet code= "smileface.java" height="600" width="600">  
  </applet>  
  */  
 public class smileface extends java.applet.Applet implements Runnable {  
    int aflag;  
    Thread t;  
   public void init() {  
     t=new Thread(this); aflag=0;  
     t.start();  
   }  
   public void run()  
   {  
    try  
    {  
    if (aflag==0)  
     {  
     t.sleep(1000);  
     aflag=1;  
    } else  
     {  
     t.sleep(1000);  
     aflag=0;  
    }  
    repaint();   
     run();  
    }  
    catch(Exception e)  
    {  
    }  
   }  
   public void paint(Graphics g) {  
    g.drawOval(100,100,100,100);  
    g.fillOval(120,125,20,20);  
    g.fillOval(160,125,20,20);  
    g.drawLine(150,135,150,165);  
    if (aflag==0)  
     { g.drawArc(140,160,20,20,0,-180);  
     aflag=1;  
    }  
    else  
    {  
     g.drawArc(140,160,20,20,0,180);  
     aflag=0;  
    }  
   }  
 }  

OUTPUT :