队列的使用

//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by Fernflower decompiler)
//

package com.atguigu.queue;

//使用数组模拟队列-编写一个ArrayQueue类
class ArrayQueue {
    int maxSize; //表示数组的最大容量
    int front; // 队列头
    int rear; // 队列尾
    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（就是队列最后一个数据）
    }

    //判断队列是否满
    public boolean isFull() {
        return this.rear == this.maxSize - 1;
    }

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

    public void addQueue(int n) {
        if (isFull()) {
            System.out.println("队列满，不能加入数据~");
        } else {
            ++this.rear; //让rear后移
            this.arr[this.rear] = n;
        }

    }

    public int getQueue() {
        if (isEmpty()) {
            throw new RuntimeException("队列空，不能取数据");
        } else {
            ++this.front;  //front后移
            return this.arr[this.front];
        }
    }


    public void showQueue() {
        if (isFull()) {
            System.out.println("队列空的，没有数据~~");
        } else {
            for (int i = 0; i < arr.length; i++) {
                System.out.printf("arr[%d]=%d\n", i, this.arr[i]);
            }
        }
    }


    public int headQueue() {
        if (isEmpty()) {
            throw new RuntimeException("队列空的，没有数据~~");
        } else {
            return this.arr[this.front + 1];
        }
    }
}

//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by Fernflower decompiler)
//

package com.atguigu.queue;

import java.util.Scanner;

public class ArrayQueueDemo {
    public ArrayQueueDemo() {
    }

    public static void main(String[] args) {
        ArrayQueue queue = new ArrayQueue(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);
            int res;
            switch(key) {
                case 'a':
                    System.out.println("输出一个数");
                    int value = scanner.nextInt();
                    queue.addQueue(value);
                    break;
                case 'e':
                    scanner.close();
                    loop = false;
                    break;
                case 'g':
                    try {
                        res = queue.getQueue();
                        System.out.printf("取出的数据是%d\n", res);
                    } catch (Exception var8) {
                        System.out.println(var8.getMessage());
                    }
                    break;
                case 'h':
                    try {
                        res = queue.headQueue();
                        System.out.printf("队列头的数据是%d\n", res);
                    } catch (Exception var7) {
                        System.out.println(var7.getMessage());
                    }
                    break;
                case 's':
                    queue.showQueue();
            }
        }

        System.out.println("程序退出~~");
    }
}