循环队列的创建及演示（Java日记三）_循环队列创建-优快云博客

本文链接：https://blog.youkuaiyun.com/Starry_error/article/details/123576396

本文档详细解析了循环队列中关键公式，包括 rear+1 对 maxsize 取余等于 front 和 rear 与 front 的差加上 maxsize 再取余的推导过程，适合初学者理解队列操作原理。

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本篇只是日记不做过多的讲解，不明白公式

(rear+1)%maxsize==front，

(rear-front+maxsize)%maxsize

如何推导请移步(2条消息) 循环队列中公式的推导，原理，超详解_星空的你的博客-优快云博客

代码如下：

import java.util.Scanner;

public class CircleQueueDemo {
    public static void main(String[] args) {
        CircleQueue queue=new CircleQueue(3);
        Scanner scan=new Scanner(System.in);
        boolean loop=true;
        while(loop){
            System.out.print("请输入命令:");
            char key=scan.next().charAt(0);
            switch (key){
                case 'a':
                    try {
                        System.out.print("输入要添加的数:");
                        int n=scan.nextInt();
                        queue.addQueue(n);
                    } catch (Exception e) {
                        System.out.println(e.getMessage());
                    }
                    break;
                case 'g':
                    try {
                        int elem=queue.getQueue();
                        System.out.println("已取出元素:"+elem);
                    } catch (Exception e) {
                        System.out.println(e.getMessage());

                    }
                    break;
                case 's':
                    try {
                        queue.showQueue();
                    } catch (Exception e) {
                        System.out.println(e.getMessage());
                    }
                    break;
                case 'h':
                    try {
                        queue.headQueue();
                    } catch (Exception e) {
                        System.out.println(e.getMessage());
                    }
                    break;
                case 'e':
                    scan.close();
                    loop=false;
                    System.out.println("程序退出！");
                    break;
                default:
                    break;
            }
        }
    }
}
class CircleQueue{
    private int maxsize;
    private int front;
    private int rear;
    private int[] arr;
    public CircleQueue(int maxsize){
        this.maxsize=maxsize;
        arr=new int[maxsize];
        front=0;
        rear=0;
    }
    public boolean isFull(){
        return (rear+1)%maxsize==front;
    }
    public boolean isEmpty(){
        return front==rear;
    }
    public void addQueue(int n){
        if(isFull()){
            throw new RuntimeException("添加失败,队已满~");
        }
        arr[rear++]=n;
        rear=rear%maxsize;

    }
    public int getQueue(){
        if(isEmpty()){
            throw new RuntimeException("取出失败,队已空~");
        }
        int n=arr[front++];
        front=front%maxsize;
        return n;
    }
    public void showQueue(){
        if(isEmpty()){
            throw new RuntimeException("无法显示,队已空~");
        }
        for (int i = 0; i <(rear-front+maxsize)%maxsize ; i++) {
            System.out.println(arr[(front+i)%maxsize]);//此处需要特别注意
        }
    }
    public void headQueue(){
        if(isEmpty()){
            throw new RuntimeException("无法显示,队已空~");
        }
        System.out.println(arr[front]);
    }
}