栈实现队列

package test.com; import java.util.Stack; /** * 1.栈实现队列 */ public class Hui03_StackToQueue { /* 使用两个栈实现队列 */ public Stack<Integer> pushStack = new Stack<>(); //用来入队列 public Stack<Integer> popStack = new Stack<>(); //用来出队列 public void enQueue(Integer data){ pushStack.push(data); } public Integer deQueue(){ //当popStack为空时，要全部将pushStack栈中元素弹出，并压入到popStack中 if(popStack.isEmpty()){ if(pushStack.isEmpty()){ return null; } while (!pushStack.isEmpty()) popStack.push(pushStack.pop()); } //否则，说明popStack不为空，直接弹出即可 return popStack.pop(); } public static void main(String[] args) { Hui03_StackToQueue queue = new Hui03_StackToQueue(); queue.enQueue(1); queue.enQueue(9); queue.enQueue(7); System.out.println(queue.deQueue()); queue.enQueue(4); System.out.println(queue.deQueue()); queue.enQueue(5); System.out.println(queue.deQueue()); } }