数组实现环形队列

代码如下：

public class CircleQueue {
    //初始化数组的长度，用来判断
    private int maxSize;
    //起始索引
    private int front;
    //结束索引
    private int rear;
    //初始数组
    private int[] arr;
    
    //初始化参数
    public CircleQueue (int maxSize){
        this.maxSize = maxSize;
        arr = new int[maxSize];
        front = 0;
        rear = 0;
    }
    
    public boolean isEmpty () {
        return rear == front;
    }
    //因为rear和front一直是紧挨着的
    //所以只要rear+1就应该是front
    //所以算法是(rear+1)%maxSize==front
    public boolean isFull () {
        return (rear + 1) % maxSize == front;
    }
    
    public void add (int n) {
        if(isFull()){
            System.put.prinln("queue is full.");
            return;
        }
        //直接将数据加入
        arr[rear] = n;
        //将rear后后移
        rear = (rear + 1) % maxSize;
    }
    
    public int get () {
        if(isEmpty()){
            System.put.prinln("queue is empty.");
            return;
        }
        int result = arr[front];
        front = (front + 1) % maxSize;
        return result;
    }
    
    //显示队列所有数据
    public void show () {
        if(isEmpty){
            System.out.println("empty");
            return;
        }
        //假设maxSize=5,fron=2,rear=0
        //这确实是对的
        for(int i = front; i <front + size();i++){
            System.out.printf("arr[%d]=%d/t",i%maxSize,arr[i%maxSize]);
        }
    }
    
    public int size () {
        return (rear + maxSize - front) % maxSize;
    } 
}

关注点：
（1）(rear + maxSize - front) % maxSize用来求有效元素个数
（2） i <front +（(rear + maxSize - front) % maxSize）控制循环次数
（3）数组需要消耗一个空间来作为rear指向