Wait and Notify

[shruti patel]

Why Wait and notify are kept in Object class although they are used only with Thread Class?

[Rob Spoor]

Because you can now use any object as a lock, not just thread objects.

[Ankit Garg]

wait and notify are called on objects whose lock a thread holds

eg

class A
{
    synchronized void func1()
    {
       try
       {
         System.out.println("Waiting");
         this.wait();                      //waits and releases the lock
       }
       catch(Exception e){}
    }
    synchronized void func2()
    {
       try
       {
         System.out.println("Notifying");
         this.notifyAll();                  //wakes up all threads waiting to be notified on this object
       }
       catch(Exception e){}
    }
}
class WaitNotifyTry
{
    public static void main(String[] args)
    {
         final A obj = new A();
         Thread t1 = new Thread(new Runnable()
                                   {
                                        public void run()
                                        {
                                            obj.func1();
                                        }
                                   });
         t1.start();
         Thread t2 = new Thread(new Runnable()
                                   {
                                        public void run()
                                        {
                                            obj.func2();
                                        }
                                   });
         t2.start();
    }
}