494. implement stack by two queues

public class  {
    
     * @param x: An integer
     * @return: nothing
     */
    private Queue<Integer> queue1;
    private Queue<Integer> queue2;
    public () {
        queue1 = new LinkedList<Integer>();
        queue2 = new LinkedList<Integer>();
    }

    private void moveItem(Queue<Integer> que1, Queue<Integer> que2) { // 其实这个也不用传参
        while (que1.size() > 1) {
            que2.offer(que1.poll());
        }
    }
    private void swap() { // 不能通过传参实现！！！pass by value
        Queue<Integer> temp = queue2;
        queue2 = queue1;
        queue1 = temp;
    }
    public void push(int x) {
        // write your code here
        queue1.offer(x);
    }

    
     * @return: nothing
     */
    public void pop() {
        // write your code here
        // queue 1 to queue 2 except last item
        moveItem(queue1, queue2);
        // get last item
        int result = queue1.poll();
        // queue2 and queue 1 exchange
        swap();
    }

    
     * @return: An integer
     */
    public int top() {
        // write your code here
        //queue 1 to queue 2 except last item
        moveItem(queue1, queue2);
        // get last item
        int result = queue1.poll();
        // put last item to queue 2
        queue2.offer(result);
        // queue 2 and queue 1 exchange
        swap();
        return result;
    }

    
     * @return: True if the stack is empty
     */
    public boolean isEmpty() {
        // write your code here
        // queue1.isEmpty
        return queue1.isEmpty();
    }
}