Java - avoiding NonSuchElementException using ConcurrentLinkedDeque

tal :

Building a multi thread program i ran into a problem: the ConcurrentLinkedDeque's remove method was called by two threads and threw an exception. i can fix the problem by sync this method the way i did in this code, but i'm looking for a solution without synchronization. I searched for other suitable structures but havn't find any that doesn't throw exception or wait for the queue to be filled again.

    public void releaseVehicle(DeliveryVehicle vehicle) {
    acquireTable.put(vehicle.getLicense(), true);
    synchronized (futureQueue) {
        if (!futureQueue.isEmpty())
            futureQueue.remove().resolve(vehicle);    

    }
}     

i'm curious, is there another way?

Slaw :

You can use poll instead. Since ConcurrentLinkedDeque doesn't allow null elements, poll returning null means the deque is empty (at the time of calling).

SomeClass element;
while ((element = deque.poll()) != null) {
    // do something with element
}