.net - On On Error Resume Next时出错

Question

我无法建立exe:

1> ------ Assembly started: project: B, Configuration: Debug Any CPU

B.vb (38.9): error BC36595: The method can not simultaneously contain an "On Error Resume Next" statement and define a variable that is used in the lambda expression or query expression.

Assembling: successful: 0, with errors: 1, no change: 0, skipped: 0

从第37行到第48行:

Sub Read(ByVal ar As IAsyncResult)
    On Error Resume Next
    If TCP.GetStream.DataAvailable And TCP.GetStream.CanRead Then
        Dim tt As New Thread(AddressOf Data) : tt.IsBackground = True : tt.SetApartmentState(ApartmentState.STA) : tt.Start(DirectCast(bf.Deserialize(TCP.GetStream), Byte()))
        TCP.GetStream.Flush() : TCP.GetStream.BeginRead(New Byte() {0}, 0, 0, AddressOf Read, Nothing)
        Exit Sub
    Else
        GoTo r
    End If 
r:
    Disconnect()
End Sub

我正在尝试使用try \ catch，但是不知道，对吗？ :

Sub Read(ByVal ar As IAsyncResult)
    Try
        If TCP.GetStream.DataAvailable And TCP.GetStream.CanRead Then
            Dim tt As New Thread(AddressOf Data) : tt.IsBackground = True : tt.SetApartmentState(ApartmentState.STA) : tt.Start(DirectCast(bf.Deserialize(TCP.GetStream), Byte()))
            TCP.GetStream.Flush() : TCP.GetStream.BeginRead(New Byte() {0}, 0, 0, AddressOf Read, Nothing)
            Exit Sub
        End If
    Catch
        GoTo r
    Finally
    End Try
r:
    Disconnect()
End Sub

Answer 1

该错误消息上的documentation告诉您如何解决它:

To correct this error

1. Replace the exception handling code that uses the On Error Goto statement with a Try...Catch statement.

试用...捕获将包含以下部分:

Try-应该执行什么

Catch-如果在Try

中引发异常，应该执行什么操作

Finally-无论是否存在异常，应执行什么操作。

I'm trying to use try\catch, but don't know, is that correct?

它可能有效，但是 Exit Sub和 Goto是不必要的并且使事情变得困惑。我会尝试:

Sub Read(ByVal ar As IAsyncResult)
    Try
        If TCP.GetStream.DataAvailable And TCP.GetStream.CanRead Then
            Dim tt As New Thread(AddressOf Data) : tt.IsBackground = True : tt.SetApartmentState(ApartmentState.STA) : tt.Start(DirectCast(bf.Deserialize(TCP.GetStream), Byte()))
            TCP.GetStream.Flush() : TCP.GetStream.BeginRead(New Byte() {0}, 0, 0, AddressOf Read, Nothing)
        End If
    Catch
        Disconnect()
    Finally
    End Try
End Sub

但是，只有在出现异常时才调用 Disconnect()似乎很奇怪。否则连接应该保持打开状态吗？ call 者如何知道是否已调用 Disconnect？