数组模拟环形队列

  1 public class CircleArrayQueueDemo {
  2     public static void main(String[] args) {
  3         // 测试，创建队列 最大值为 3 方便测试
  4         CircleArrayQueue aq = new CircleArrayQueue(4);
  5         char key = ‘ ‘;// 接收用户输入
  6         Scanner input = new Scanner(System.in);
  7         boolean loop = true;
  8         while (loop) {
  9             System.out.println("s(show) 显示队列");
 10             System.out.println("e(exit) 退出程序");
 11             System.out.println("a(add) 添加队列");
 12             System.out.println("g(get) 取出队列");
 13             System.out.println("h(head) 展示队列");
 14             key = input.next().charAt(0);// 接收输入字符
 15             switch (key) {
 16             case ‘s‘:
 17                 aq.showQueue();
 18                 break;
 19             case ‘a‘:
 20                 System.out.println("请输入数字：");
 21                 int v = input.nextInt();
 22                 aq.addQueue(v);
 23                 break;
 24             case ‘g‘:
 25                 try {
 26                     int reslut = aq.getQueue();
 27                     System.out.println("取出的数据是 -- " + reslut);
 28                 } catch (Exception e) {
 29                     System.out.println(e.getMessage());
 30                 }
 31                 break;
 32             case ‘h‘:// 查看队列头
 33                 try {
 34                     int head = aq.headQueue();
 35                     System.out.println("队列头的数据是 -- " + head);
 36                 } catch (Exception e) {
 37                     System.out.println(e.getMessage());
 38                 }
 39             case ‘e‘:// 退出
 40                 input.close();
 41                 loop = false;
 42                 break;
 43             default:
 44                 break;
 45             }
 46         }
 47         System.out.println("------exit------");
 48 
 49     }
 50 }
 51 
 52 //使用数组模拟队列
 53 class CircleArrayQueue {
 54     private int maxSize;// 数组最大容量
 55     private int front; // 指向队列头部
 56     private int rear; // 队列尾部后一个元素，即 即将被叫号的那个元素
 57     private int arr[]; // 该数组用于模拟队列存储数据
 58 
 59     // 构造器
 60     public CircleArrayQueue(int arrMaxSize) {
 61         maxSize = arrMaxSize;
 62         arr = new int[maxSize];
 63     }
 64     // 编写队列的方法
 65     // 判断队列是否满
 66     public boolean isFull() {
 67         return (rear + 1) % maxSize == front;
 68     }
 69 
 70     // 判断队列是否为空
 71     public boolean isEmpty() {
 72         return rear == front;
 73     }
 74 
 75     // 添加队列
 76     public void addQueue(int n) {
 77         if (isFull()) {
 78             System.out.println("队列已满，请稍后！");
 79             return;
 80         }
 81         arr[rear] = n;
 82         rear = (rear + 1) % maxSize;
 83     }
 84 
 85     // 获取数据
 86     public int getQueue() {
 87         if (isEmpty()) {
 88             // 通过抛出异常处理
 89             throw new RuntimeException("队列为空！");
 90         }
 91         int v = arr[front];
 92         front = (front + 1) % maxSize;
 93         return v;
 94     }
 95 
 96     // 遍历队列数据
 97     public void showQueue() {
 98         if (isEmpty()) {
 99             System.out.println("队列为空！");
100             return;
101         }
102         for (int i = front; i < front + size(); i++) {
103             System.out.printf("arr[%d] = %d\n", i % maxSize, arr[i % maxSize]);
104         }
105     }
106 
107     // 返回当前数组有效数据数目
108     public int size() {
109         return (rear + maxSize - front) % maxSize;
110     }
111 
112     // 展示队列头部信息
113     public int headQueue() {
114         if (isEmpty()) {
115             throw new RuntimeException("队列为空,无数据！");
116         }
117         return arr[front];
118     }
119 }