模拟队列

数组模拟队列1

/**
 * @author cjj_1
 * @date 2020-07-31 15:16
 */
public class Queue
{
    public static void main(String[] args) throws Exception {
        QueueArray qa = new QueueArray(3);
        Scanner s = new Scanner(System.in);
        boolean loop = true;
        char key ;
        while (loop)
        {
            System.out.println("s(show)：代表展示队列");
            System.out.println("a(add)：队列添加");
            System.out.println("g(get)：取出数据");
            System.out.println("f(print)：获取头");
            System.out.println("e(exit)：程序退出！");
            key = s.next().charAt(0);
            switch (key){
                case 's':
                    qa.showQueue();
                    break;
                case 'a':
                    qa.addQueue(s.nextInt());
                    break;
                case 'g':
                    try {
                        qa.fetchQueue();//出队
                    }catch (Exception e){
                        System.out.println(e.getMessage());
                    }

                    break;
                case 'f':
                    System.out.println(qa.fetchHead());
                    break;
                case 'e':
                    s.close();
                    loop=false;
                    break;
                default:break;
            }
        }

    }
    @Test
    public void queue4Array() {

    }
    /*
     * 内部类
     * @author cjj_1
     * @date 2020-07-31 15:19:40
     * @param null
     * @return
     **/
   static class QueueArray{
        int maxLength ;//对列的最大长度
        int front ;//队列头
        int rear;//队列尾部
        int[] arr;
        public QueueArray(int arrayMaxSize){
            maxLength = arrayMaxSize;
            arr = new int[maxLength];
            rear = -1;
            front = -1;
        }

        /**
         * 判断队列是否满了
         * @return
         */
        public boolean ifFull(){
            return maxLength == rear+1;
        }

        /**
         * 判断队列是否为空
         * @return
         */
        public boolean isEmpty(){
            return rear == front;
        }
        /**
         * 判断队列是否为空
         * @return
         */
        public void addQueue(int n) throws Exception {
            if(ifFull()){
                System.out.println("队列已经满。。。");
               return;
            }
            rear++;
            arr[rear] = n;
        }
    /*
     * 取数据
     * @author cjj_1
     * @date 2020-07-31 16:23:29
     * @param n
     * @return
     **/
        public int fetchQueue() throws Exception {
            if(isEmpty()){
                System.out.println("队列已空。。。");
                throw new Exception("队列已空。。。");
            }
            return front++;

        }

        /**
         * 展示队列
         * @throws Exception
         */
        public void showQueue() throws Exception {
            if(isEmpty())
                return;
           for(int i= front+1;i <=rear;i++)
                System.out.println(arr[i]);
//            front++;
        }
        /**
         * 取头部信息
         * @throws Exception
         */
        public int fetchHead() throws Exception {
            if(isEmpty())
                return -1;
            return arr[++front];
        }


    }
}