Prove safety offer five: two stacks achieved a queue

Title Description

Two stacks to achieve a queue, the completion queue Push and Pop operations. Queue elements int.

package com.jianzhioffer;

import java.util.Stack;

public class TwoStacks {
	Stack<Integer> stack1 = new Stack<Integer>();
    Stack<Integer> stack2 = new Stack<Integer>();
    
    public void push(int node) {
    	stack1.push(node);
    }
    
    public int pop() {
	    if(stack2.isEmpty()){
	    	while(!stack1.isEmpty())
	    	{
	    		stack2.push(stack1.pop());
	    	}
	    }
    	return stack2.pop();
    }
    
	public static void main(String[] args) throws Exception{
		TwoStacks s = new TwoStacks();
		s.push(1);
		s.push(2);
		
		int n = s.pop();
		System.out.println(n);
		s.push(3);
		n = s.pop();
		System.out.println(n);
		n = s.pop();
		System.out.println(n);
		s.push(4);
		n = s.pop();
		System.out.println(n);
	}
}

Summary: The use of two stacks realize the function of a queue, very interesting, which requires advanced features that take full advantage of the stack. A first data push to the stack, then the B to A stack element pop the stack, the stack will be B A stack of such elements and a lower inverted.