在vb.net中實現IDictionary接口

Question

我正在嘗試在VB.net中實現IDictionary接口，但出現錯誤。 請同樣幫我。

Imports System.Collections.Generic

Public Class DataDictionary Implements IDictionary(Of String, Object)
Private _ce As CalcEngine.CalcEngine
Private _dct As Dictionary(Of String, Object)

Public Sub New(ByVal ce As CalcEngine.CalcEngine)
    _ce = ce
    _dct = New Dictionary(Of String, Object)()
End Sub

#Region "IDictionary<string,object> Members"

Public Sub Add(ByVal key As String, ByVal value As Object) Implements Collections.Generic.IDictionary(Of String, Object).Add
    _dct.Add(key, value)
End Sub
Public Function ContainsKey(ByVal key As String) As Boolean Implements System.Collections.Generic.IDictionary(Of String, Object).ContainsKey
    Return _dct.ContainsKey(key)
End Function
Public ReadOnly Property Keys() As ICollection(Of String) Implements System.Collections.Generic.IDictionary(Of String, Object).Keys
    Get
        Return _dct.Keys
    End Get
End Property
Public Function Remove(ByVal key As String) As Boolean Implements System.Collections.Generic.IDictionary(Of String, Object).Remove
    Return _dct.Remove(key)
End Function
Public ReadOnly Property Values() As ICollection(Of Object) Implements System.Collections.Generic.IDictionary(Of String, Object).Values
    Get
        Return _dct.Values
    End Get
End Property
Public Function TryGetValue(ByVal key As String, ByRef value As Object) As Boolean Implements System.Collections.Generic.IDictionary(Of String, Object).TryGetValue
    If _dct.TryGetValue(key, value) Then
        Dim expr = TryCast(value, String)
        If expr IsNot Nothing AndAlso expr.Length > 0 AndAlso expr(0) = "="c Then
            value = _ce.Evaluate(expr.Substring(1))
        End If
        Return True
    End If
    Return False
End Function
Default Public Property Item(ByVal key As String) As Object Implements System.Collections.Generic.IDictionary(Of String, Object).Item
    Get
        Dim value As Object
        If TryGetValue(key, value) Then
            Return value
        End If
        Throw New Exception("invalid index")
    End Get
    Set(ByVal value As Object)
        _dct(key) = value
    End Set
End Property
#End Region


 #Region "ICollection<KeyValuePair<string,object>> Members"

Public Sub Add(ByVal item As KeyValuePair(Of String, Object)) Implements System.Collections.Generic.ICollection(Of KeyValuePair(Of String, Object)).Add
    Dim d = TryCast(_dct, ICollection(Of KeyValuePair(Of String, Object)))
    d.Add(item)
End Sub
Public Sub Clear() Implements System.Collections.Generic.ICollection(Of KeyValuePair(Of String, Object)).Clear
    _dct.Clear()
End Sub
Public Function Contains(ByVal item As KeyValuePair(Of String, Object)) As Boolean Implements System.Collections.Generic.ICollection(Of KeyValuePair(Of String, Object)).Contains
    Dim d = TryCast(_dct, ICollection(Of KeyValuePair(Of String, Object)))
    Return d.Contains(item)
End Function
Public Sub CopyTo(ByVal array As KeyValuePair(Of String, Object)(), ByVal arrayIndex As Integer) Implements System.Collections.Generic.ICollection(Of KeyValuePair(Of String, Object)).CopyTo
    Dim d = TryCast(_dct, ICollection(Of KeyValuePair(Of String, Object)))
    d.CopyTo(array, arrayIndex)
End Sub
Public ReadOnly Property Count() As Integer Implements System.Collections.Generic.ICollection(Of KeyValuePair(Of String, Object)).Count
    Get
        Return _dct.Count
    End Get
End Property
Public ReadOnly Property IsReadOnly() As Boolean Implements System.Collections.Generic.ICollection(Of KeyValuePair(Of String, Object)).IsReadOnly
    Get
        Return False
    End Get
End Property
Public Function Remove(ByVal item As KeyValuePair(Of String, Object)) As Boolean Implements System.Collections.Generic.ICollection(Of KeyValuePair(Of String, Object)).Remove
    Dim d = TryCast(_dct, ICollection(Of KeyValuePair(Of String, Object)))
    Return d.Remove(item)
End Function
#End Region


#Region "IEnumerable<KeyValuePair<string,object>> Members"

    Public Function GetEnumerator() As IEnumerator(Of KeyValuePair(Of String, Object)) Implements IEnumerable(Of KeyValuePair(Of String, Object)).GetEnumerator

    Return TryCast(_dct.GetEnumerator(), IEnumerator(Of KeyValuePair(Of String, Object)))
End Function

#End Region

#Region "IEnumerable Members"

Private Function GetEnumerator() As System.Collections.IEnumerator Implements System.Collections.IEnumerable.GetEnumerator
    Return TryCast(_dct.GetEnumerator(), System.Collections.IEnumerator)
End Function

#End Region
End Class

當我編譯時出現以下錯誤：

錯誤1類'DataDictionary'必須為接口'System.Collections.Generic.IEnumerable（Of System.Collections.Generic.KeyValuePair（Of String，Object）實現'Function GetEnumerator（）As IEnumerator（Of KeyValuePair（Of String，Object））' ））'。 H：\\ Test \\ WindowsApplication1 \\ WindowsApplication1 \\ ProbeDataDictionary.vb 4 16 WindowsApplication1

錯誤3'公共函數GetEnumerator（）作為System.Collections.Generic.IEnumerator（Of System.Collections.Generic.KeyValuePair（字符串，對象））'和'私有函數GetEnumerator（）作為System.Collections.IEnumerator'無法重載其他，因為它們僅在返回類型上有所不同。 H：\\ Test \\ WindowsApplication1 \\ WindowsApplication1 \\ ProbeDataDictionary.vb 96 21 WindowsApplication1

提前致謝。

Answer 1

您已經錯過了一種GetEnumerator方法的接口實現聲明：

Public Function GetEnumerator() As IEnumerator(Of KeyValuePair(Of String, Object))

應該

Public Function GetEnumerator() As IEnumerator(Of KeyValuePair(Of String, Object)) Implements IEnumerable(Of KeyValuePair(Of String, Object)).GetEnumerator

更新資料

好的，您的方法應如下所示：

Public Function GetEnumeratorGeneric() As IEnumerator(Of KeyValuePair(Of String, Object)) Implements IEnumerable(Of KeyValuePair(Of String, Object)).GetEnumerator
    Return _dct.GetEnumerator()
End Function

這是因為即使兩個方法實現了不同的接口，也不能使用兩個具有相同名稱的方法。

Answer 2

以下代碼可用於實現IDictionary接口

Imports System.Collections.Generic

Public Class DataDictionary
Implements IDictionary(Of String, Object)
Private _ce As CalcEngine.CalcEngine
Private _dct As Dictionary(Of String, Object)

Public Sub New(ByVal ce As CalcEngine.CalcEngine)
    _ce = ce
    _dct = New Dictionary(Of String, Object)()
End Sub

'---------------------------------------------------------------
#Region "IDictionary<string,object> Members"

Public Sub Add(ByVal key As String, ByVal value As Object) Implements Collections.Generic.IDictionary(Of String, Object).Add
    _dct.Add(key, value)
End Sub
Public Function ContainsKey(ByVal key As String) As Boolean Implements System.Collections.Generic.IDictionary(Of String, Object).ContainsKey
    Return _dct.ContainsKey(key)
End Function
Public ReadOnly Property Keys() As ICollection(Of String) Implements System.Collections.Generic.IDictionary(Of String, Object).Keys
    Get
        Return _dct.Keys
    End Get
End Property
Public Function Remove(ByVal key As String) As Boolean Implements System.Collections.Generic.IDictionary(Of String, Object).Remove
    Return _dct.Remove(key)
End Function
Public ReadOnly Property Values() As ICollection(Of Object) Implements System.Collections.Generic.IDictionary(Of String, Object).Values
    Get
        Return _dct.Values
    End Get
End Property
Public Function TryGetValue(ByVal key As String, ByRef value As Object) As Boolean Implements System.Collections.Generic.IDictionary(Of String, Object).TryGetValue
    If _dct.TryGetValue(key, value) Then
        Dim expr = TryCast(value, String)
        If expr IsNot Nothing AndAlso expr.Length > 0 AndAlso expr(0) = "="c Then
            value = _ce.Evaluate(expr.Substring(1))
        End If
        Return True
    End If
    Return False
End Function
Default Public Property Item(ByVal key As String) As Object Implements System.Collections.Generic.IDictionary(Of String, Object).Item
    Get
        Dim value As Object
        If TryGetValue(key, value) Then
            Return value
        End If
        Throw New Exception("invalid index")
    End Get
    Set(ByVal value As Object)
        _dct(key) = value
    End Set
End Property
#End Region

'---------------------------------------------------------------
#Region "ICollection<KeyValuePair<string,object>> Members"

Public Sub Add(ByVal item As KeyValuePair(Of String, Object)) Implements System.Collections.Generic.ICollection(Of KeyValuePair(Of String, Object)).Add
    Dim d = TryCast(_dct, ICollection(Of KeyValuePair(Of String, Object)))
    d.Add(item)
End Sub
Public Sub Clear() Implements System.Collections.Generic.ICollection(Of KeyValuePair(Of String, Object)).Clear
    _dct.Clear()
End Sub
Public Function Contains(ByVal item As KeyValuePair(Of String, Object)) As Boolean Implements System.Collections.Generic.ICollection(Of KeyValuePair(Of String, Object)).Contains
    Dim d = TryCast(_dct, ICollection(Of KeyValuePair(Of String, Object)))
    Return d.Contains(item)
End Function
Public Sub CopyTo(ByVal array As KeyValuePair(Of String, Object)(), ByVal arrayIndex As Integer) Implements System.Collections.Generic.ICollection(Of KeyValuePair(Of String, Object)).CopyTo
    Dim d = TryCast(_dct, ICollection(Of KeyValuePair(Of String, Object)))
    d.CopyTo(array, arrayIndex)
End Sub
Public ReadOnly Property Count() As Integer Implements System.Collections.Generic.ICollection(Of KeyValuePair(Of String, Object)).Count
    Get
        Return _dct.Count
    End Get
End Property
Public ReadOnly Property IsReadOnly() As Boolean Implements System.Collections.Generic.ICollection(Of KeyValuePair(Of String, Object)).IsReadOnly
    Get
        Return False
    End Get
End Property
Public Function Remove(ByVal item As KeyValuePair(Of String, Object)) As Boolean Implements System.Collections.Generic.ICollection(Of KeyValuePair(Of String, Object)).Remove
    Dim d = TryCast(_dct, ICollection(Of KeyValuePair(Of String, Object)))
    Return d.Remove(item)
End Function
#End Region

'---------------------------------------------------------------
#Region "IEnumerable<KeyValuePair<string,object>> Members"

Public Function GetEnumerator2() As IEnumerator(Of KeyValuePair(Of String, Object)) Implements IEnumerable(Of KeyValuePair(Of String, Object)).GetEnumerator
    Return TryCast(_dct.GetEnumerator(), IEnumerator(Of KeyValuePair(Of String, Object)))
End Function

#End Region

'---------------------------------------------------------------
#Region "IEnumerable Members"

Private Function GetEnumerator() As System.Collections.IEnumerator Implements System.Collections.IEnumerable.GetEnumerator
    Return TryCast(_dct.GetEnumerator(), System.Collections.IEnumerator)
End Function
#End Region
End Class