A Queue Implemented With Two Stacks

public class DoubleStackQueue<E> {
    private Stack<E> enqueue = new Stack<E>(), dequeue = new Stack<E>();
    private void move(Stack<E> from, Stack<E> to) {
        while (!from.empty()) to.push(from.pop());
    }
    public void enqueue(E element) {
        if (!dequeue.empty()) move(dequeue, enqueue);
        enqueue.push(element);
    }
    public E dequeue() {
        if (isEmpty()) throw new IllegalStateException();
        if (!enqueue.empty()) move(enqueue, dequeue);
        return dequeue.pop();
    }
    public boolean isEmpty() {
        return enqueue.empty() && dequeue.empty();
    }
}