Thread Vs. Thread

[Nabila Mohammad]

Can some one explain why the first thread runs printing A and B , where as the second thread throws an exception.
The source is http://www.javaranch.com


Is it because in the second program the object doesnot have a refernce name?

public class Run {
    public static void main(String[] args) {
        System.out.print("A ");
        final Object test = new Object();
        synchronized (test) {
            test.notifyAll();
        }
        System.out.println("B");
    }
}
    

 public class Run {
    public static void main(String[] args) {
        System.out.print("A ");
        synchronized (new Object()) {
            new Object().notifyAll();
        }
        System.out.println("B");
    }
}
   

[ September 10, 2008: Message edited by: Nabila Mohammad ]

[Ankit Garg]

The second one throws MonitorStateException. This is because when you do this

synchronized(new Object())//separate object
{
new Object.notifyAll();//separate object
}

as you may know that you must hold the lock of the object that you call wait, notify and notifyAll on. But in this case, the synchronized block uses a different object and the notifyAll call uses a separate object of the Object class..

[ankit kumar]

ya in the second progrmme you are creating again the new Object . you are not using the previous object.

[Nabila Mohammad]

Thanks.
Why didn't i think of that....