用两个栈实现一个队列

【题目】两个栈实现一个队列

import java.util.Stack;

public class Main {

    public static void main(String[] args) {

        Stack<Integer> stack1 = new Stack<Integer>();
        Stack<Integer> stack2 = new Stack<Integer>();

        MyQueue myQueue = new MyQueue(stack1, stack2);

        myQueue.appendTail(1);
        myQueue.appendTail(2);
        myQueue.appendTail(3);
        System.out.println(myQueue.deleteHead());
        System.out.println(myQueue.deleteHead());
        myQueue.appendTail(4);
        myQueue.appendTail(5);
        System.out.println(myQueue.deleteHead());
        System.out.println(myQueue.deleteHead());
        System.out.println(myQueue.deleteHead());
        System.out.println(myQueue.deleteHead());

    }

}

class MyQueue {

    private Stack<Integer> stack1;
    private Stack<Integer> stack2;

    public MyQueue(Stack<Integer> stack1, Stack<Integer> stack2) {
        this.stack1 = stack1;
        this.stack2 = stack2;
    }

    public Boolean appendTail(Integer num) {
        Boolean result = false;
        if (null != num) {
            stack1.push(num);
            result = true;
        }
        return result;
    }

    public Integer deleteHead() {
        if (!stack2.isEmpty()) {
            return stack2.pop();
        }

        if (stack2.isEmpty() && !stack1.isEmpty()) {
            int length = stack1.size();
            for (int i = 0; i < length; i++) {
                Integer temp = stack1.pop();
                stack2.push(temp);
            }
            return stack2.pop();
        }

        return null;
    }

    public Stack<Integer> getStack1() {
        return stack1;
    }

    public void setStack1(Stack<Integer> stack1) {
        this.stack1 = stack1;
    }

    public Stack<Integer> getStack2() {
        return stack2;
    }

    public void setStack2(Stack<Integer> stack2) {
        this.stack2 = stack2;
    }

}