异常

Question

后继续代码，我想知道是否有办法让一个异常被抛出后的程序继续进行。例如：

Try 
    line 1 
    line 2 
    line 3 
    line 4 (here the exception is thrown and jumps to the catch) 
    line 5 <-- i would like the program to continue its execution loging the error 
    line 6 

Catch ex as Exception 
    log(ex.tostring) 
End Try 

谢谢。

Answer 1

如果你这样做，你知道如何从恢复或不是重要的东西，你应该包装在try/catch语句只是符合特定的渔获物。 例如

Try 
    line 1 
    line 2 
    line 3 
    Try 
    line 4 (here the exception is throw and jumps to the catch) 
    Catch iox as IOException ' or whatever type is being thrown 
    'log it 
    End Try 
    line 5 <-- i would like the program to continue its execution after loggin the error 
    line 6 

Catch ex as Exception 
    log(ex.tostring) 
End Try 

Answer 2

VB.net不支持这种类型的构造。一旦异常展开堆栈，它就不能再次展开。有些语言允许你恢复异常，但它们需要更复杂的堆栈管理 - 本质上是协程。

Answer 3

try 
    line 1 
catch ex as exception 
    log(ex.tostring) 
end try 
try 
    line 2 
catch ex as exception 
    log(ex.tostring) 
end try 
try 
    line 3 
catch ex as exception 
    log(ex.tostring) 
end try 
try 
    line 4 (here the exception is throw and jumps to the catch) 
catch ex as exception 
    log(ex.tostring) 
end try 
try 
    line 5 <-- i would like the program to continue its execution after loggin the error 
catch ex as exception 
    log(ex.tostring) 
end try 
try 
    line 6 
catch ex as exception 
end try 

Answer 4

虽然On Error Resume Next是still available in VB.NET，它是相互排斥的结构化异常处理的优选方法。

相反，我会建议使用Try..Catch..Finally块的Finally条款，以确保Line 5 and Line 6得到执行，即使4号线（或前行）抛出。

Try 
    line 1 
    line 2 
    line 3 
    line 4 
Catch ex as Exception 
    log(ex.tostring) 
Finally 
    line 5 
    line 6 
End Try 

Answer 5

如果我没有记错的“最佳实践处理异常的说：”如果你可以检查一个错误，很可能会发生，然后检查这一条件。如果你可以检查dbnull然后这样做。

Answer 6

使用“继续”

不是好的做法随处可见，但有用的在某些情况下，例如找到一个文件，而处理拒绝访问某些目录：

Dim dir As New DirectoryInfo("C:\") 
    Dim strSearch As String = ("boot.ini") 

    For Each SubDir As DirectoryInfo In dir.GetDirectories 
     Try 
      For Each File As FileInfo In SubDir.GetFiles 
       Console.WriteLine("Sub Directory: {0}", SubDir.Name) 
       If File.Name = strSearch Then 
        Console.Write(File.FullName) 
       End If 
      Next 
     Catch ex As Exception 
      Console.WriteLine(ex.Message) 
      Continue For 
     End Try 
    Next 

Answer 7

这里是代码的例子：

Sub yourSub() 
    Dim cDelegate As CatchDelegate = Sub(ex As Exception) 
             Your Catch Code 
            End Sub 
line 1 
line 2 
line 3 
TCResumeNext(Sub() line 4, cDelegate) 
line 5 
line 6 
End Sub 

Delegate Sub CatchDelegate(e As Exception) 

Sub TCResumeNext(tryDelegate As [Delegate], catchDelgate As CatchDelegate) 
    Try 
    tryDelegate.DynamicInvoke() 
    Catch ex As Exception 
     catchDelgate.DynamicInvoke(ex) 
    End Try 
End Sub 

Answer 8

相当旧的文章，但为他人着想。 我个人使用“的错误恢复下一步”，在这种情况下，它是一个必要的邪恶