[英]VB.NET Should I use a collection for this?
I am trying to bring my old VB6 code to a modern VB.NET code. 我正在尝试将旧的VB6代码引入现代VB.NET代码。
In my VB6 code, I need to query if a key exists in a collection. 在我的VB6代码中,我需要查询集合中是否存在键。
I do it like this: 我这样做是这样的:
Private Function pIndexFromKey(ByRef uCol As Collection, ByVal uText As String) As Long
On Error Resume Next
Dim lRet&
lRet = uCol.Item(uText)
pIndexFromKey = lRet
End Function
If pIndexFromKey returns 0, I know that the key is not contained in the collection, and I add it like this: 如果pIndexFromKey返回0,则表示该键未包含在集合中,因此我将其添加为:
nCollection.Add(lIndex, sText)
I am wondering if this is "nice" approach. 我想知道这是否是“不错”的方法。 I think not because in .NET I am using a VisualBasic collection, and the fact that it is "VB" and not a system collection makes me suspicious.
我认为不是因为在.NET中我使用的是VisualBasic集合,而事实是它是“ VB”而不是系统集合,这使我感到怀疑。
Just for the records, this is my VB.NET code: 仅作记录,这是我的VB.NET代码:
Private Function pIndexFromKey(ByRef uCol As Collection, ByVal uText As String) As Integer
On Error Resume Next
Dim lRet As Integer = CInt(uCol(uText))
Return lRet
End Function
The code works fine, but my On Error Resume Next approach looks ugly, and I don't like having the debug window telling me about the exception each time the error is thrown (and eaten). 代码可以正常工作,但是我的On Error Resume Next方法看起来很丑陋,而且我不希望每次抛出(和吃掉)错误时都让调试窗口告诉我有关异常的信息。
Does anybody have any better ideas? 有人有更好的主意吗?
您可以简单地使用contains方法来检查密钥是否存在。
I wouldn't use " on errer resume next" approach. 我不会使用“下一个错误恢复”方法。 just Test the collection using "contains" method.
只需使用“包含”方法测试集合。
Dim Ret as integer
Ret=0
If (uCol.contains(uText)) then
Ret= CInt(uCol(uText))
Return ret
Drop your VB collection and use the advanced Generic List. 删除您的VB集合并使用高级通用列表。
In your case I suspect you are using a simple List(Of String). 在您的情况下,我怀疑您使用的是简单的List(Of String)。
If so, use this replacement for your method 如果是这样,请将此替代方法用于您的方法
Dim k as List(Of String) = new List(Of String)
k.Add("Test1")
k.Add("Test2")
k.Add("Test3")
k.Add("Test4")
k.Add("Test5")
' No need to use Contains, IndexOf doesn't throw exceptions if the element is not there
Dim x = k.IndexOf("Test4")
if x = -1 then
Console.WriteLine("Test4 is not in list")
else
Console.WriteLine("Test4 is at index" + x.ToString)
End if
You could use a Generic.Dictionary (Of String, Integer). 您可以使用Generic.Dictionary (字符串,整数)。 So instead of this:
所以代替这个:
Private Function pIndexFromKey(ByRef uCol As Collection, ByVal uText As String) As Integer
On Error Resume Next
Dim lRet As Integer = CInt(uCol(uText))
Return lRet
End Function
You would have this: 您将拥有:
Private Function pIndexFromKey(dict As Dictionary(Of String, Integer), uText As String) As Integer
Dim lRet As Integer
If dict.TryGetValue(uText, lRet) Then Return lRet
Return -1 'default value if key was not found in the dictionary
End Function
If you have Vb.Net that you can handle the error in the Try use Example: Try 如果您拥有Vb.Net,则可以在“尝试使用示例:尝试”中处理错误。
Catch ex As Exception 异常捕获
End Try 结束尝试
I hope I understand correctly 我希望我能正确理解
I'd replace the VisualBasic.Collection
with the ObjectModel.Collection(Of T)
for starters. 对于初学者,我将
VisualBasic.Collection
替换为ObjectModel.Collection(Of T)
。 Then, get rid of your custom function and just check the Contains()
method. 然后,摆脱您的自定义函数,仅检查
Contains()
方法。
Dim nCollection As New ObjectModel.Collection(Of String)
Dim sText As String = "value"
If Not nCollection.Contains(sText) Then
nCollection.Add(uText)
End If
If nCollection.Contains(sText) Then
Dim index = nCollection.IndexOf(sText)
End If
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