Saburo data structure algorithm study notes: array simulation queue system

Use the array to simulate the queue
characteristics: first in, first out
Algorithm idea: here we use the array to simulate the queue,
assuming that the upper limit of the array capacity MaxSize is
placed with the head and tail pointers

Result demonstration:

/*
* author:sanalang
* time:2020.10.25
* function: ArrayQueue based on array
* */
import java.util.Scanner;
class ArrayQueueDemo {
    public static <handle> void main(String[] args) {
        //测试一把
        //创建一个队列
        ArrayQueue queue = new ArrayQueue(3);
        char key = ' '; //接收用户输入
        Scanner scanner = new Scanner(System.in);
        boolean loop = true;
        //输出一个菜单
        while(loop) {
            System.out.println("s(show): 显示队列");
            System.out.println("e(exit): 退出程序");
            System.out.println("a(add): 添加数据到队列");
            System.out.println("g(get): 从队列取出数据");
            System.out.println("h(head): 查看队列头的数据");
            key = scanner.next().charAt(0);
            //接收一个字符
            switch (key) {
                case 's': queue.showQueue(); break;
                case 'a': System.out.println("输出一个数");
                          int value = scanner.nextInt();
                          queue.addQueue(value);
                          break;
                case 'g': //取出数据
                    try { int res = queue.getQueue();
                        System.out.printf("取出的数据是%d\n", res);
                    } catch (Exception e) {
                        //TODO:
                        handle exception;
                        System.out.println(e.getMessage());
                    } break;
                case 'h': //查看队列头的数据
                    try {
                        int res = queue.headQueue();
                        System.out.printf("队列头的数据是%d\n", res);
                    } catch (Exception e) {
                        // TODO:
                        handle exception;
                        System.out.println(e.getMessage());
                    }
                    break;
                case 'e': //退出
                    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 ArrayQueue {
    private int maxSize; // 表示数组的最大容量
    private int front; // 队列头
    private int rear; // 队列尾
    private int[] arr; //  该数据用于存放数据,  模拟队列
    // 创建队列的构造器
    public ArrayQueue(int arrMaxSize) {
        maxSize = arrMaxSize;
        arr = new int[maxSize];
        front = -1;
        // 指向队列头部，分析出 front 是指向队列头的前一个位置.
        rear = -1;
        // 指向队列尾，指向队列尾的数据(即就是队列最后一个数据)
    }
    // 判断队列是否满
    public boolean isFull() {
        return rear == maxSize - 1;
    }
    //判断队列是否为空
    public boolean isEmpty() {
        return rear == front;
    }
    // 添加数据到队列
    public void addQueue(int n) { // 判断队列是否满
        if (isFull()) {
            System.out.println("队列满，不能加入数据~");
            return;
        }
        rear++; // 让 rear 后移
        arr[rear] = n;
    }
    // 获取队列的数据, 出队列
    public int getQueue() {
        // 判断队列是否空
        if (isEmpty()) {
            // 通过抛出异常
            throw new RuntimeException("队列空，不能取数据");
        }
        front++; // front 后移
        return arr[front];
    }
    // 显示队列的所有数据
    public void showQueue() {
    // 遍历
        if (isEmpty()) {
        System.out.println("队列空的，没有数据~~");
        return;
    }
        for (int i = 0; i < arr.length; i++)
        {
        System.out.printf("arr[%d]=%d\n", i, arr[i]);
        }
}
    // 显示队列的头数据， 注意不是取出数据
    public int headQueue() {
        // 判断
        if (isEmpty()) {
            throw new RuntimeException("队列空的，没有数据~~");
        }
        return arr[front + 1];
    }
}

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