数组模拟队列，队列先进先出

数组模拟队列，队列先进先出

public class ArrayQueueDemo {
    public static void main(String[] args) {
        ArrayQueue arrayQueue = new ArrayQueue(3);
        char key=' ';//接收用户输入
        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):");
            System.out.println("a(add):添加数据");
            System.out.println("g(get):取出数据");
            System.out.println("h(head):取出头部数据");
            key=scanner.next().charAt(0);
            switch(key)
            {
                case 's':
                    arrayQueue.showQueue();
                    break;
                case'a':
                    System.out.println("请输入一个数字");
                    int value = scanner.nextInt();
                    arrayQueue.Add(value);
                    break;
                case 'g':
                    try{
                        int res=arrayQueue.getQueue();
                        System.out.println(res);
                    }catch (Exception e)
                    {
                        System.out.println(e.getMessage());
                    }
                    break;
                case 'h':
                    try{
                        int res=arrayQueue.headQueue();
                        System.out.println(res);
                    }catch (Exception e)
                    {
                        System.out.println(e.getMessage());
                    }
                    break;
                case 'e':
                    scanner.close();
                    loop=false;
                    break;
                default:
                    break;
            }

        }
        System.out.println("程序退出");
    }
}
class ArrayQueue{
    private int maxSize;//队列的最大容量
    private int front;//对头
    private int rear;//队列尾
    private int[] arr;//存放数据，模拟队列
    public ArrayQueue(int arrMaxSize)
    {
        maxSize=arrMaxSize;
        arr=new int[maxSize];
        front=-1;//队列头的前一个位置
        rear=-1;//队列的尾部
    }
    public boolean isFull(){
        return rear==maxSize-1;
    }
    public boolean isEmpty(){
        return front==rear;
    }

    public void Add(int n)
    {
        if(isFull())
        {
            System.out.println("队列已满，不能加入");
            return;
        }
        rear++;
        arr[rear]=n;
        //arr[++rear]=n;
    }
    public int getQueue(){
        if(isEmpty())
        {
            throw new RuntimeException("队列为空，不能取出");
        }
        front++;
        return arr[front];
    }
    //展示数据
    public void showQueue()
    {
        if(isFull())
        {
            System.out.println("队列为空，没有数据");
        }
        for(int i=0;i<arr.length;i++)
        {
            System.out.println(arr[i]);
        }
    }
    public int headQueue()
    {
            if (isEmpty()){
                    throw new RuntimeException("队列为空，没有数据");
            }
            return arr[front+1];
    }
}