Question

我有许多类都实现了相同的接口。 e.g。

Public Class IncidentAsset
    Implements IModelWithIdentity

    Private _assetId As Int16
    Private _otherAsset As String

    Private _asset As Asset

    Public Property AssetId() As Int16
        Get
            Return _assetId
        End Get
        Set(ByVal value As Int16)
            _assetId = value
        End Set
    End Property

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

    Public Property Asset() As Asset
        Get
            Return _asset
        End Get
        Set(ByVal value As Asset)
            _asset = value
        End Set
    End Property

    Public Function GetId() As String Implements IModelWithIdentity.GetId
        Return _assetId.ToString()
    End Function
End Class

我有另一个带有这些对象列表的对象。

    Public Property IncidentAssetsDamaged() As List(Of IncidentAsset)
        Get
            Return _incidentAssetsDamaged
        End Get
        Set(ByVal value As List(Of IncidentAsset))
            _incidentAssetsDamaged = value
        End Set
    End Property

我需要编写一个方法，使用接口的GetId（）方法返回逗号分隔的Id字符串。

这是我到目前为止所做的：

    Public Shared Function ToCommaSeparatedStringOfIds(Of T)(ByVal collection As List(Of T)) As String

        Dim array As List(Of String) = New List(Of String)

        For Each obj As IModelWithIdentity In collection
            array.Add(obj.GetId())
        Next

        Return String.Join(",", array.ToArray)
    End Function

使用.NET 2.0在VB.NET中有更好的方法吗？

Answer 1

我能看到的选项很少。如果指定列表的容量，则性能将提高。因为List.Add（）需要一些额外的步骤来调整集合的大小。

为什么不使用stringbuilder，并在每个id的末尾添加逗号。

Dim builder As New StringBuilder（）

 For Each obj As IModelWithIdentity In collection
            builder.Append(obj.GetId()).append(",")
 Next
Dim res = builder.ToString()

但这可能会在最后增加一个逗号。

您可以使用索引器和常规for循环对此进行排序。

Dim builder As New StringBuilder()
     For i = 0 To collection.Count - 2
          builder.Append(collection(i).GetId()).append(",")
     Next
     builder.Append(collection(collection.Count -1))

    Dim res = builder.ToString()

这在逻辑上是正确的。请对此进行基准测试并确认结果。

将List（of T）转换为逗号分隔的Id字符串

1 个答案: