队列和环形队列_一人流年的博客_队列和环形队列

代码实现：

package com.springboot.dataStructure.queue;

import java.util.Scanner;

/**
 * @author: 牧羊
 * @Date: 2020/4/14 0:04
 * 数组模拟队列
 * 缺点：用了一次就不能用了，不能复用
 * 优化：修改成环形队列
 */
public class ArrayQueueDemo {

    public static void main(String[] args) {

        //创建一个队列
        ArrayQueue arrayQueue = new ArrayQueue(3);

        char key; //接收用户输入

        Scanner scanner = new Scanner(System.in);

        boolean loop = true;

        while (loop){
            System.out.println("s(show):显示队列");
            System.out.println("e(exit):退出");
            System.out.println("a(add):添加");
            System.out.println("g(get):获取");
            System.out.println("h(head):显示队列头的数据");

            key = scanner.next().charAt(0);//接收一个字符

            switch (key){
                case 's':
                    arrayQueue.showQueue();
                    break;
                case 'e':
                    scanner.close();
                    loop = false;
                    break;
                case 'a':
                    System.out.println("输出一个数");
                    int value = scanner.nextInt();
                    arrayQueue.addQueue(value);
                    break;
                case 'g':
                    System.out.println(arrayQueue.getQueue());
                    break;
                case 'h':
                    System.out.println(arrayQueue.headQueue());
                    break;
                default:
                    break;
            }
        }
        System.out.println("程序退出");

    }

}

class ArrayQueue{
    //表示数组的最大值
    private int maxSize;
    //表示队列头
    private int front;
    //表示队列尾
    private int rear;
    //用于存放数据
    private int[] arr;

    //创建队列构造器
    public ArrayQueue(int maxSize){
        this.maxSize = maxSize;
        this.front = -1;
        this.rear = -1;
        this.arr = new int[maxSize];
    }

    //判断队列是否满
    public boolean isFull(){
        return rear == maxSize -1;
    }

    //判断队列是否为空
    public boolean isEmpty(){
        return front == rear;
    }

    //添加数据到队列
    public void addQueue(int n){
        if(isFull()){
            System.out.println("队列已满，不能添加数据");
            return;
        }
        rear++;
        arr[rear] = n;
    }

    //出队列
    public int getQueue(){
        if(isEmpty()){
            System.out.println("队列为空");
            return 0;
        }
        front++;
        return arr[front];
    }

    //显示队列的所有数据
    public void showQueue(){
        if(isEmpty()){
            System.out.println("队列为空");
        }

        for(int i = front+1 ; i <= rear ; i++){
            System.out.printf("arr[%d]=%d\n",i,arr[i]);
        }
    }

    //显示队列的头数据
    public int headQueue(){
        if(isEmpty()){
            System.out.println("队列为空");
            return 0;
        }
        return arr[front+1];
    }

}
package com.springboot.dataStr