How to catch TypeInitializationException?
How can I catch this TypeInitializationException
?开发者_如何学JAVA Don't really care if it is C# or VB.NET code. Here is some sample code of what I am trying to figure out (this is not real code - just something to show what I am dealing with):
Public Class Test
Public Shared testObj as Object = CreateObj()
Public Shared Function CreateObj() as Object
throw new Exception("Ha!")
End Function
Public Shared Sub Main()
Dim i as Integer = 0
End Sub
End Class
Suppose I have no control over CreateObj
method.
In VB you have a couple of options depending on what type of application it is.
If the Application is a console app or windows form app then you can extend the My class with an UnhandledException event.
Namespace My
Partial Friend Class MyApplication
Private Sub MyApplication_UnhandledException(ByVal sender As Object, ByVal e As Microsoft.VisualBasic.ApplicationServices.UnhandledExceptionEventArgs) Handles Me.UnhandledException
'Handle error here
End Sub
End Class
End Namespace
If it's an ASP.Net web app then add some code to the Global.asax file (events below truncated for brevity).
Public Class Global_asax
Inherits System.Web.HttpApplication
Sub Application_Error(ByVal sender As Object, ByVal e As EventArgs)
' Fires when an error occurs
End Sub
Private Sub Global_asax_Error(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Error
'Catches all errors
End Sub
End Class
As a rule you shouldn't call a method from a type initializer. Use the class initializer to set the initial value in your Sub Main.
Just use a Try/Catch
block, as for any other exception... If Main
is the program entry point, you're out of luck, because the exception might be thrown before you have a chance to catch it. I say "might" because I'm not sure about the rules regarding type initialization in VB; if they're the same as in C# 4, the code you posted will run fine, because the type initializer won't be executed until it's actually necessary, and in your code it's never necessary (because testObj
is never used)
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