阅读CSV文件大多数已预订的房间

Question

public String[] getTopRoomsBooked(int n) {

    HashMap<String, Integer> rooms = new HashMap<String, Integer>();

    rooms.put("Gower", 281);
    rooms.put("Usk", 291);
    rooms.put("Wye", 283);
    rooms.put("Bala", 282);
    rooms.put("Pen y Fan", 292);
    rooms.put("Llangorse", 290);
    rooms.put("Snowdon", 288);
    rooms.put("Taff", 296);
    rooms.put("Cadair Idris", 292);

    for (String i : rooms.keySet()) {
        System.out.println("Room name: " + i + " Amount of time: " + rooms.get(i));
    }

    System.out.println();

    List<Integer> timeBooked = new ArrayList<>(rooms.values());

    Collections.sort(timeBooked, Collections.reverseOrder());

    if (n == 1) {
        System.out.println("RoomName : Taff " + timeBooked.get(n - 1));
    } else if (n == 3) {
        System.out.println("1: Taff " + timeBooked.get(n - 3));
        System.out.println("2: Cadiar Idris " + timeBooked.get(n - 2));
        System.out.println("3: Pen y Fan " + timeBooked.get(n - 1));

    } else if (n == 5) {
        System.out.println("1: Taff " + timeBooked.get(n - 5));
        System.out.println("2: Cadair Idris " + timeBooked.get(n - 4));
        System.out.println("3: Pen y Fan " + timeBooked.get(n - 3));
        System.out.println("4: Usk " + timeBooked.get(n - 2));
        System.out.println("5: Llangorse " + timeBooked.get(n - 1));
    } else if (n == 9) {
        System.out.println("1: Taff " + timeBooked.get(n - 9));
        System.out.println("2: Cadair Idris " + timeBooked.get(n - 8));
        System.out.println("3: Pen y Fan " + timeBooked.get(n - 7));
        System.out.println("4: Usk " + timeBooked.get(n - 6));
        System.out.println("5: Llangorse " + timeBooked.get(n - 5));
        System.out.println("6: Snowden " + timeBooked.get(n - 4));
        System.out.println("7: Wye " + timeBooked.get(n - 3));
        System.out.println("8: Bala " + timeBooked.get(n - 2));
        System.out.println("9: Gower " + timeBooked.get(n - 1));
    }

    return null;

}

可以使用以下功能使用Java 8流来实现这一点：

Comparator.comparing(...).thenComparing()

Answer 1

Map.Entry<String, Integer>

输出量
• limit

  重新映射到房间名称（键hashmap中的键）

• map

  将房间名称收集到字符串阵列

• 确定

  rooms

  hashmap是在方法之外填充的，并作为参数提供，让我们将其重写如下：collect(Collectors.toList()).toArray(String[]::new)

• 测试和输出

rooms

在线演示