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我有一个实现 IDataReader 的类并编写了所需的函数，但我收到一条错误消息说明

类“CSVDataReader”必须为接口“System.Data.IDataRecord”实现“函数 GetBoolean(i As Integer) As Boolean”。

IDataReader 具有许多功能和属性。如何在不重写所有功能的情况下实现这些功能？

这是我的课

    Public Class CSVDataReader
    Implements IDataReader
    Private stream As StreamReader
    Private columnsByName As New Dictionary(Of String, Integer)()
    Private columnsByOrdinal As New Dictionary(Of Integer, String)()
    Private currentRow As String()
    Private _isClosed As Boolean = True

    Public Sub New(fileName As String)
        If Not File.Exists(fileName) Then
            Throw New Exception("File [" & fileName & "] does not exist.")
        End If

        Me.stream = New StreamReader(fileName)

        Dim headers As String() = stream.ReadLine().Split(",")
        For i As Integer = 0 To headers.Length - 1
            columnsByName.Add(headers(i), i)
            columnsByOrdinal.Add(i, headers(i))
        Next

        _isClosed = False
    End Sub

    Public Sub Close()
        If stream IsNot Nothing Then
            stream.Close()
        End If
        _isClosed = True
    End Sub

    Public ReadOnly Property FieldCount() As Integer
        Get
            Return columnsByName.Count
        End Get
    End Property

    ''' <summary>
    ''' This is the main function that does the work - it reads in the next line of data and parses the values into ordinals.
    ''' </summary>
    ''' <returns>A value indicating whether the EOF was reached or not.</returns>
    Public Function Read() As Boolean
        If stream Is Nothing Then
            Return False
        End If
        If stream.EndOfStream Then
            Return False
        End If

        currentRow = stream.ReadLine().Split(",")
        Return True
    End Function

    Public Function GetValue(i As Integer) As Object
        Return currentRow(i)
    End Function

    Public Function GetName(i As Integer) As String
        Return columnsByOrdinal(i)
    End Function

    Public Function GetOrdinal(name As String) As Integer
        Return columnsByName(name)
    End Function

    Public Function GetOrdinal(name As String) As Integer
        Return columnsByName(name)
    End Function
End Class
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1 回答 1

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您必须实现所有方法和属性。

接口是一种契约——如果一个对象说它可以提供接口上列出的服务，它必须提供所有这些服务。接口不是基类——如果你不实现某些东西，就没有“模板”代码可以依靠。

不将任何代码放在您不感兴趣的方法/属性中是可以的（我通常放Throw New NotImplementedException这样我知道什么时候我无意中调用了我不打算调用的方法）。但是存根必须在那里。

于 2012-11-08T19:43:15.073 回答