[java] Multithreaded Problem [Solved]

Hello people, I've a small problem with my multithreaded server... I've one thread who accepts requests and pushes them into a vector:

private Vector jobList_;
private java.util.concurrent.Semaphore jobListSema_;
private java.util.concurrent.Semaphore jobListEmptySema_;

	public void pushJob( JobEntry job )
	{
		try
		{		
			jobListSema_.acquire();
			jobList_.add( job );
			jobListSema_.release();
			jobListEmptySema_.tryAcquire();
			jobListEmptySema_.release();
			
		} catch( InterruptedException e )
		{
		}
	}

With the following initialization in my constructor:

jobList_ = new Vector();
		jobListSema_ = new java.util.concurrent.Semaphore( 1 );
		jobListEmptySema_ = new java.util.concurrent.Semaphore( 1 );

		jobListEmptySema_.tryAcquire();

And i've an other thread, who removes those jobs:

public JobEntry popJob()
	{
		JobEntry res;
		try
		{
			if( jobList_.isEmpty() )
				jobListEmptySema_.acquire();
			jobListSema_.acquire();

			res = (JobEntry) jobList_.remove( 0 );
			jobListSema_.release();

		} catch( InterruptedException e )
		{
			res = null;
		}
		
		return res;
	}

And now after some time (and about 500 jobs) I get:

Exception in thread "Thread-0" java.lang.ArrayIndexOutOfBoundsException: Array i
ndex out of range: 0
        at java.util.Vector.remove(Vector.java:793)
        at LoungeServer.popJob(LoungeServer.java:173)
        at LoungeServer.run(LoungeServer.java:152)

Which is exactly the remove in popJob() But I don't understand how this can happen, as I thought the jobListEmptySema_ garantuees my jobList_ is not empty, when I acquire the Sempahore in popJob... Thanks for your help. [Edited by - Sparhawk42 on September 16, 2005 8:00:07 AM]