wait() and notify()

[Raghav Mathur]

public class waitnotify implements Runnable
{
public boolean i;

public void run()
{
}

public synchronized void setBool()
{
if(i== false)
{
try{
wait(500);
}catch(Exception e){}
}


}
public static void main(String []arg)
{
a w = new a();
a A = new a();
Thread t = new Thread(w);
Thread t1 = new Thread(A);
//t.setDaemon(true);
//t1.setDaemon(true);
t.start();

t1.start();
}
}
class a extends waitnotify
{
public void run()
{
setBool();
setBooltr();

}
public synchronized void setBooltr()
{
i = true;
System.out.println("notified");
notify();

}
}
please tell how to implemnt wait () and notify() in synchronized code . I have got the concept but unable to implement . The following code calls the wait() method but is not getting the notification . please correct it and explain the concept with actual implementation .
thanks a ton
regards
raghav mathur

[Rajinder Yadav]

Here you go
This class creates two threads objects from the Ping and Pong class, each thread output's the string "Ping" and "Pong" respectivly.
The code uses wait and notify to get the two thread to work together to output the string, "PingPong"

// class PingPongTest
class PingPongTest
{   
   public static void main(String[] argv) {
      PingPongTest t = new PingPongTest();
      t.play();
   }
   
   public void play() {
      Thread m_ping = new Thread(new Ping(this));
      Thread m_pong = new Thread(new Pong(this));
    
      m_ping.start();
      m_pong.start();
   } 
}

// class Ping
class Ping implements Runnable
{
   PingPongTest m_ppt;
   
   Ping(PingPongTest ref) {
      m_ppt = ref;
   }
   
   public void run() {
      synchronized(m_ppt) {
         for(int i=0; i<100; ++i) {
            try {            
               System.out.print("Ping");
               m_ppt.notify();
               m_ppt.wait();
            }
            catch(InterruptedException e) {
            }
         } // for()
         m_ppt.notify();
      } // sync     
   }
}

// class Pong
class Pong implements Runnable
{
   PingPongTest m_ppt;
      
   Pong(PingPongTest ref) {
      m_ppt = ref;
   }
   
   public void run() {
      synchronized(m_ppt) {               
         for(int i=0; i<100; ++i) {
            try {
               System.out.println("Pong");
               m_ppt.notify();
               m_ppt.wait();
            }
            catch(InterruptedException e) {
            }
         } // for()
         m_ppt.notify();
      } //sync
   }
}

[ March 02, 2002: Message edited by: Rajinder Yadav ]