public class CircleQueue {

private int maxSize;       //有一个数据是空的,用于rear的约定,实际数据容量比maxsize少一个

private int front = 0;     //指向队列头部的第一个元素

private int rear = 0;      //指向队列尾部最后一个数据的后一位置,默认情况没有数据最后一位是-1

private int[] array = new int[maxSize];

public CircleQueue(int maxSize) {
    this.maxSize = maxSize;
}

private boolean isFull() {
    return (rear + 1) % maxSize == front;       //加1后判断指正尾部和头部数值是否一致
}

private boolean isEmpty() {
    return front == rear;
}

public void addQueue(int value) {
    if (isFull()) {
        System.out.println("队列满的");
        return;
    }
    array[rear] = value;
    rear = (rear + 1) % maxSize;
}

public int getQueue() {
    if (isEmpty()) {
        throw new RuntimeException("队列空的");
    }
    int value = array[front];
    front = (front + 1) % maxSize;
    return value;
}

public int headQueue() {
    if (isEmpty()) {
        throw new RuntimeException("队列空的");
    }
    return array[front];
}

public void show() {
    if (isEmpty()) {
        System.out.println("队列空的");
        return;
    }
    for (int i = front; i < front + getDataSize(); i++) {
        System.out.printf("array[%d]=%d\n", i % maxSize, array[i % maxSize]);
    }
}

private int getDataSize() {
    return (rear + maxSize - front) % maxSize;      //队列数据最多一列,相当于求绝对值
}

}