Code example for NoSuchElementException

    public Object remove() {
        Object x = poll();
        if (x != null)
            return x;
            throw new NoSuchElementException();
     * Retrieves, but does not remove, the head of this queue.  This method 
     * differs from {@link #peek peek} only in that it throws an exception if 
     * this queue is empty. 
     * <p>This implementation returns the result of <tt>peek</tt> 
     * unless the queue is empty. 
     * @return the head of this queue 
     * @throws NoSuchElementException if this queue is empty 
    public Object element() {