java--算法--队列

数组模拟队列：

1. 　

   package com.model.queue;
   
   
   import java.util.Scanner;
   
   /**
    * @Description:测试类
    * @Author: 张紫韩
    * @Crete 2021/6/24 20:39
    *
    * 数组模拟队列，并验证
    */
   public class ArrayQueueDemo01 {
       public static void main(String[] args) {
   
           ArrayQueue queue=new ArrayQueue(3);
   
           Scanner scanner = new Scanner(System.in);
   
           char key=‘ ‘;
   
           Boolean loop=true;
           while (loop){
               System.out.println("s(show):显示队列");
               System.out.println("e(exit):退出程序");
               System.out.println("a(add):添加数据到队列");
               System.out.println("g(get):从队列中取出数据");
               System.out.println("h(head):查看队列的头数据");
               key=scanner.next().charAt(0);
               switch (key){
                   case ‘s‘:
                       queue.showQueue();
                       break;
                   case ‘e‘:
                       scanner.close();
                       loop=false;
                       break;
                   case ‘a‘:
                       System.out.println("请输入一个选择");
                       int n=scanner.nextInt();
                       queue.addQueue(n);
                       break;
                   case ‘g‘:
                       try {
                           int res=queue.getQueue();
                           System.out.printf("取出的数据是%d\n",res);
                       }catch (Exception e){
                           System.out.println(e);;
                       }finally {
   
                       }
                       break;
                   case ‘h‘:
                       try {
                           int head= queue.headQueue();
                           System.out.printf("取出的数据是%d\n",head);
                       }catch (Exception e){
                           System.out.println(e);
                       }finally {
   
                       }
   
                       break;
                   default:
                       break;
   
               }
   
           }
           System.out.println("退出程序");
       }
   
   }
   class ArrayQueue{
       private int maxSize;  //队列的最大长度
       private int front;   //指向队列头部的前一个
       private int rear;   //指向队列的尾部
       private int[] arr;   //数组模拟队列
   
       public ArrayQueue(int maxSize) {
           this.maxSize = maxSize;
           arr=new int[maxSize];
       }
       boolean isFull(){
           return maxSize-1==rear;
       }
       boolean isEmpty(){
           return rear==front;
       }
   
       //添加元素
       public void addQueue(int n){
           //判断队列是否满了
           if(isFull()){
               System.out.println("队列已满，不能添加元素");
           }
           rear++;
           arr[rear]=n;
       }
       //获取元素
       public int getQueue(){
           //判断对了是否为空
           if (isEmpty()){
               throw new RuntimeException();
           }
           front++;
           return arr[front];
       }
   
       //遍历所有的元素
       public void showQueue(){
           if (isEmpty()){
               System.out.println("队列为空没有数据");
           }
           for (int i = 0; i < arr.length; i++) {
               System.out.printf("arr[%d]=%d\n",i,arr[i]);
           }
       }
   
       //获得头数据
       public int headQueue(){
           if (isEmpty()){
               throw new RuntimeException("队列为空");
           }
           return arr[front+1];
       }
   
   }