数组实现队列(循环队列)

package com.dai.queue;

import java.util.Scanner;

public class CircleArrayQueue {

    public static void main(String[] args) {
        //创建一个环形队列对象
        CircleArray arrayQueue = new CircleArray(4);//有效空间只有3
        char key = ' ';
        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):退出队列");
            System.out.println("a(append):添加数据到队列");
            System.out.println("g(get):从队列取出数据");
            System.out.println("h(head):查看队列头数据");
            key = scanner.next().charAt(0);
            switch (key) {
            case 's':
                arrayQueue.showQueue();
                break;
            case 'a':
                System.out.println("输入数字：");
                int value = scanner.nextInt();
                arrayQueue.addQueue(value);
                break;
            case 'g':
                try {
                    int res = arrayQueue.getQueue();
                    System.out.printf("取出的数据是%d
",res);
                }catch(Exception e) {
                    System.out.println(e.getMessage());
                }
                break;
            case 'h':
                try {
                    int res = arrayQueue.headQueue();
                    System.out.printf("队列头的数据是%d
",res);
                }catch(Exception e) {
                    System.out.println(e.getMessage());
                }
                break;
            case 'e':
                scanner.close();
                loop = false;
                break;
            default:
                break;
            }
            
        }
        System.out.println("程序退出");
    }
}
        //使用数组模拟队列，编写一个ArrayQueue类
class CircleArray{
    private int maxSize;
    private int front;
    private int rear;
    private int[] arr;
    public CircleArray(int arrMaxSize) {
        maxSize = arrMaxSize;
        arr = new int[maxSize];
    }
    public boolean isFull() {
        return (rear+1)%maxSize == front;
    }
    public boolean isEmpty() {
        return rear==front;
    }
    public void addQueue(int n) {
        if (isFull()) {
            System.out.println("队列满，不能加入数据");
            return;
        }
        arr[rear] = n;
        rear = (rear+1)%maxSize;
    }
    public int getQueue() {
        if(isEmpty()) {
            throw new RuntimeException("队列空，不能取数据");
        }
        int value = arr[front];
        front = (front+1)%maxSize;
        return value;
    }
    public int size() {
        return (rear+maxSize-front)%maxSize;
    }
    public void showQueue() {
        if(isEmpty()) {
            System.out.println("队列空，无数据");
            return;
        }
        for(int i =front; i<front+size(); i++) {
            System.out.printf("arr[%d]=%d
", i%maxSize, arr[i%maxSize]);
        }
    }
    public int headQueue() {
        if(isEmpty()) {
            throw new RuntimeException("队列空，无数据");
        }
        return arr[front];
    }
}