vb.net - 添加到列表中的自定义属性类别

Question

这似乎是我应该知道的事情，也许它工作正常，但对我来说看起来是错误的。我希望将数据库查询中的一些数据添加到一个列表中，我创建了一个自定义属性类来保存该列表。

我的类(class):

Public Class MyClass
    Private _Col1 As String
    Private _Col2 As String
    Private _Col3(,) As Object
    Private _Col4 As String

    Public Property Col1() As String
        Get
            Return _Col1
        End Get
        Set(ByVal value As String)
            _Col1 = value
        End Set
    End Property

    Public Property Col2() As String
        Get
            Return Col2
        End Get
        Set(ByVal value As String)
            Col2= value
        End Set
    End Property

    Public Property Col3() As Object(,)
        Get
            Return Col3
        End Get
        Set(ByVal value As Object(,))
            Col3= value
        End Set
    End Property

    Public Property Col4() As String
        Get
            Return Col4
        End Get
        Set(ByVal value As String)
            _Col4= value
        End Set
    End Property

    Sub New(ByVal col1 As String, ByVal col2 As String, ByVal col3 As Object, ByVal col4 As String)
        _Col1= col1
        _Col2= col2
        _Col3 = col3
        _Col4 = col4

    End Sub

 End Class

当我声明并初始化我的列表(类)然后向其中添加数据时:

Dim NList as New List(Of MyClass)

NList.Add(New MyClass("1", "2", (1,3), "3"))

当我查看列表项时，我看到列表中有 8 个项目，而不是 4 个。其中 4 个是方法，4 个是变量。这是正确的吗？类属性如何发挥作用？我似乎通过向 4 个变量添加数据来浪费资源，如果我必须循环遍历具有 40k 行的记录集，我假设它会提高性能。这是正确的工作方式吗？我计划稍后在程序中将项目添加到列表中并使用 Find() 函数，因此我觉得不需要 8 个项目而不是 4 个。

编辑:列表项

?NList.Item(0)
    _Col1: "1" {String}
    _Col2: "2"
    _Col3: "(1,3)"
    _Col4: "4"
    Col3: "(1,3)"
    Col4: "4"
    Col1: "1"
    Col2: "2"

Answer 1

在你的类(class):

Public Class MyClass
    Private _Col1 As String    ' private backing field to hold the value

    ' interface to get/set that same value
    Public Property Col1() As String
        Get
            Return _Col1
        End Get
        Set(ByVal value As String)
            _Col1 = value
        End Set
    End Property

您的类将只有一个用于该属性值的变量。在调试中，您会看到支持字段和属性接口(interface):

?NList.Item(0)
    _Col1: "1" {String}        <== backing field storing the value
    ...
    Col1: "1"                  <== property 'exposing' _Col1

请注意，使用自动实现的属性可以极大地简化您的类并放弃显式支持字段:

Public Class fooClass
    Public Property Col1() As String
    Public Property Col2() As String
    Public Property Col3() As DateTime
    Public Property Col4() As Integer

    ' VS creates hidden backing fields you can still reference in the class:
    Public Sub New(str As String ...)
        _Col1 = str
        ...
    End Sub
End Class