Question

我有关于填充list<>元素的问题。我试图将值设置为list<>对象的第一个元素，但它不起作用。这是我的两个班级：

类

        class hotel
        {
            public List<room> rooms = new List<room>();
        }
        class room
        {
            public string roomName;
        }

Form1.cs的

private void Form1_Load(object sender, EventArgs e)
        {
            string word = "example";
            hotel[] h = new hotel[3];
            for (int i = 0; i < h.Length; i++)
            {

                h[i] = new hotel();
                h[i].rooms[i].roomName = word;//It gives "Index out of range exception" error. 
            }
        }

Answer 1

您收到了错误消息，因为在您创建新的hotel时，您尚未向其中添加任何room。您的代码必须执行以下操作：

for (int i = 0; i < h.Length; i++)
{
    h[i] = new hotel();
    h[i].rooms.Add(new room { roomName = word });
}

如果您想要添加多个房间，您需要多次调用Add或在内部循环内执行此操作：

for (int i = 0; i < h.Length; i++)
{
    h[i] = new hotel();
    // Add 10 rooms
    for (int a = 0; a < 10; a++)
    {
        h[i].rooms.Add(new room { roomName = word });
    }
}

Answer 2

您尚未向酒店添加房间：

h[i] = new hotel();
var room = new room();
room.roomName = word;
h[i].rooms.Add(room);

Answer 3

使用，您需要将room添加到hotel

h[i].rooms.Add(new room {roomName = word});

而不是

h[i].rooms[i].roomName = word;

Answer 4

在您的班级中使用快捷方式可能更容易：

public class Hotel
{
    public Hotel()
    {
        Rooms = new List<Room>();
    }

    public List<Room> Rooms { get; private set; }
    public string Name { get; private set; }

    public Hotel WithName(string name)
    {
        Name = name;
        return this;
    }

    public Hotel AddRoom(string name)
    {
        Rooms.Add(new Room { Name = name });
        return this;
    }
}

public class Room
{
    public string Name { get; set; }
}

返回Hotel对象本身将允许对同一对象进行方法链接，以使操作流畅地读取。

演示：

var hotels = new List<Hotel>();

var hiltonHotel = new Hotel()
                      .WithName("Hilton")
                      .AddRoom("104")
                      .AddRoom("105");

hotels.Add(hiltonHotel);

演示2：

var hotelNames = new List<string> { "Hilton", "Sheraton", "Atlanta" };

var hotels = new List<Hotel>();

foreach(var hotelName in hotelNames)
{
    var hotel = new Hotel()
                    .WithName(hotelName);
    hotels.Add(hotel);
}

使用LINQ进行演示2：

var hotelNames = new List<string> { "Hilton", "Sheraton", "Atlanta" };
var hotels = hotelNames.Select(h => new Hotel().WithName(h)).ToList();

如何填充类中的list <t>元素？</t>

4 个答案: