用堆实现队列

package com.example.demo02;
import java.util.Stack;

/**
 * @program: demo
 * @description: 用堆实现队列
 * @author: ZCY
 * @create: 2022-01-20 16:58
 **/
public class StackToQueue {
    private Stack<Integer> pushStack;
    private Stack<Integer> popStack;

    public StackToQueue(){
    pushStack=new Stack<>();
        popStack=new Stack<>();
    }
    
    public void pushToPop(){
        if (popStack.isEmpty()){
            while (pushStack.isEmpty()){
                popStack.push(pushStack.pop());
            }
        }
    }
    
    public void add(int value){
        pushStack.push(value);
    }
    
    public int poll(){
        if (popStack.isEmpty()&&pushStack.isEmpty()){
            throw new RuntimeException("Stack is empty");
        }
        pushToPop();
        return popStack.pop();
    }
    public int peek(){
        if (popStack.isEmpty()&&pushStack.isEmpty()){
            throw new RuntimeException("Stack is empty");
        }
        pushToPop();
        return popStack.peek();
    }
}