public E poll() {
    """
	Retrieves and removes the head of this queue, or <tt>null</tt> if this queue is empty.
	
	@return The head of this queue, or <tt>null</tt> if this queue is empty.
    """
        ReentrantLock lock = this.lock;

        lock.lock();

        try
        {
            if (count == 0)
            {
                return null;
            }

            return extract(true, true).getElement();
        }
        finally
        {
            lock.unlock();
        }
    }
public E poll()
    {
        ReentrantLock lock = this.lock;

        lock.lock();

        try
        {
            if (count == 0)
            {
                return null;
            }

            return extract(true, true).getElement();
        }
        finally
        {
            lock.unlock();
        }
    }
public E poll ( ) { ReentrantLock lock = this . lock ; lock . lock ( ) ; try { if ( count == 0 ) { return null ; } return extract ( true , true ) . getElement ( ) ; } finally { lock . unlock ( ) ; } }
Retrieves and removes the head of this queue, or <tt>null</tt> if this queue is empty.

@return The head of this queue, or <tt>null</tt> if this queue is empty.
Retrieves and removes the head of this queue or <tt > null< / tt > if this queue is empty .