我是 VB.Net 中的泛型和集合的新手。我编写了第一个创建自定义对象列表的类。虽然它似乎有效,但我相信我已经以一种粗略的方式完成了它,我想知道如何为需要调用它的代码改进它。这是列表类的基本部分:
Public Class Subscribers
Public List As New List(Of Subscriber)
Public Sub New()
Dim sConnDatabase As String = ConfigurationManager.ConnectionStrings("DatabaseConnString").ConnectionString
Dim connection As New SqlConnection(sConnDatabase)
Dim cmd As SqlCommand
cmd = New SqlCommand("SELECT * FROM dbo.Subscriber_v", connection)
cmd.CommandType = CommandType.Text
connection.Open()
Dim objReader As SqlDataReader = cmd.ExecuteReader()
Do While objReader.Read()
Dim id As Integer = objReader("SubscriberID")
Dim s As Subscriber = New Subscriber(id)
List.Add(s)
Loop
objReader.Close()
connection.Close()
End Sub
End Class
这是我使用该类的第一个小测试:
Dim n As String
Dim d As Integer
Dim allSubs As New Subscribers()
For Each Subscriber In allSubs.List
n = Subscriber.SubscriberName
d = Subscriber.DaysUntilExpired.ToString()
Next
关于改进的一个具体问题是:如何让调用者编写如下代码:
For Each x In allSubs
n = x.SubscriberName
d = x.DaysUntilExpired.ToString()
Next
是否有某种方式对类进行编码,使得 allSubs 可以在不必指定 .List 的情况下表达 - 以及某种表达方式,使得 x 将被识别为订阅者类型。