java实现队列（数组结构）

下面展示一些 内联代码片。

package com.queue;

import java.util.Scanner;

class CricleArrayQueueDemo {
    public static void main(String[] args) {
        CricleArrayQueue arrayQueue = new CricleArrayQueue(6);
        Scanner scanner = new Scanner(System.in);
        boolean loop = true;
        while (loop) {
            System.out.println("a(add)添加队列");
            System.out.println("g(get)取出队列");
            System.out.println("s(show)打印队列");
            System.out.println("e(exit)退出");
            System.out.println("h(head)获取第一个");
            char k = scanner.next().charAt(0);
            switch (k) {
                case 'a':
                    System.out.println("请输入一个数字");
                    int a = scanner.nextInt();
                    arrayQueue.addQueue(a);
                    break;
                case 'g':
                    arrayQueue.getQueue();
                    break;
                case 's':
                    arrayQueue.show();
                    break;
                case 'e':
                    loop = false;
                    break;
                case 'h':
                    System.out.println(arrayQueue.getQueueHead());
                    break;
                default:
                    break;
            }
        }
    }

}

class CricleArrayQueue {

    private int[] arr;
    private int front;
    private int rear;
    private int maxSize;

    public CricleArrayQueue(int size) {
        maxSize = size;
        front = 0;
        rear = 0;
        arr = new int[maxSize];
    }

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

    public boolean isFull() {
        return (rear + 1) % maxSize == front;
    }

    public void addQueue(int a) {
        if (isFull()) {
            System.out.println("队列已满，无法添加");
            return;
        }
        arr[rear] = a;
        rear = (rear + 1) % maxSize;
    }

    public int getQueue() {
        if (isEmpty()) {
            throw new RuntimeException("队列为空，无法取队列");
        }
        int a = arr[front];
        front = (front + 1) % maxSize;
        return a;
    }

    public int getQueueHead() {
        if (isEmpty()) {
            throw new RuntimeException("队列为空，无法取队列");
        }
        return arr[front];
    }

    public void show() {
        if (isEmpty()) {
            System.out.println("数组是空的，无法打印");
            return;
        }
        for (int i = front; i < front+countQueue(); i++) {
            System.out.printf("队列第%d个：%d", i % maxSize, arr[i%maxSize]);
            System.out.println("");
        }
    }

    public int countQueue() {
        return (rear - front + maxSize) % maxSize;
    }
}