異常

Question

後繼續代碼，我想知道是否有辦法讓一個異常被拋出後的程序繼續進行。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 

謝謝。

Answer 1

如果你這樣做，你知道如何從恢復或不是重要的東西，你應該包裝在try/catch語句只是符合特定的漁獲物。 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不支持這種類型的構造。一旦異常展開堆棧，它就不能再次展開。有些語言允許你恢復異常，但它們需要更復雜的堆棧管理 - 本質上是協程。

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

雖然On Error Resume Next是still available in VB.NET，它是相互排斥的結構化異常處理的優選方法。

相反，我會建議使用Try..Catch..Finally塊的Finally條款，以確保Line 5 and Line 6得到執行，即使4號線（或前行）拋出。

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

如果我沒有記錯的「最佳實踐處理異常的說：」如果你可以檢查一個錯誤，很可能會發生，然後檢查這一條件。如果你可以檢查dbnull然後這樣做。

Answer 6

使用「繼續」

不是好的做法隨處可見，但有用的在某些情況下，例如找到一個文件，而處理拒絕訪問某些目錄：

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

這裏是代碼的例子：

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

相當舊的文章，但爲他人着想。 我個人使用「的錯誤恢復下一步」，在這種情況下，它是一個必要的邪惡