vb.net 抛出异常后如何继续运行代码？
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How to continue running code after an exception is thrown?
提问by carlos
I would like to know if there is a way to let the program continue after an exception is thrown. For example:
我想知道是否有办法在抛出异常后让程序继续运行。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, logging the error
line 6
Catch ex as Exception
log(ex.tostring)
End Try
回答by Nikki9696
If you're doing something that you know how to recover from or that isn't vital, you're supposed to wrap just that line in the try/catch with a specific catch. e.g.
如果您正在做一些您知道如何从中恢复或不重要的事情，您应该在 try/catch 中使用特定的捕获将该行包装起来。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 logging the error
line 6
Catch ex as Exception
log(ex.tostring)
End Try
回答by Eddie
Use 'Continue For'
使用“继续”
Not good practice everywhere, but useful in some circumstances, e.g. find a file while handling denied access to certain directories:
在任何地方都不是好的做法，但在某些情况下很有用，例如在处理对某些目录的拒绝访问时查找文件：
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
回答by StuartLC
Although On Error Resume Nextis still available in VB.NET, it is mutually exclusive to the preferred method of structured exception handling.
虽然On Error Resume Next是仍然在VB.NET可用，它是互斥的结构化异常处理的优选方法。
Instead, I would recommend the use of the Finallyclause of a Try..Catch..Finallyblock to ensure Line 5 and Line 6get executed even if Line 4 (or any preceding Line) throws.
相反，我建议使用块的Finally子句Try..Catch..Finally来确保Line 5 and Line 6即使第 4 行（或任何前面的行）抛出也能执行。
Try
line 1
line 2
line 3
line 4
Catch ex as Exception
log(ex.tostring)
Finally
line 5
line 6
End Try
回答by S.Lott
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 logging the error
catch ex as exception
log(ex.tostring)
end try
try
line 6
catch ex as exception
end try
回答by Thom Smith
VB.net does not support this type of construct. Once the exception unwinds the stack, it can't be unwound back again. Some languages do permit you to resume the exception, but they require more sophisticated stack management – essentially coroutines.
VB.net 不支持这种类型的构造。一旦异常展开堆栈，就不能再次展开。有些语言确实允许您恢复异常，但它们需要更复杂的堆栈管理——本质上是协程。
回答by Alex
Here is an example in code:
这是代码中的示例：
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
回答by dbasnett
If I am not mistaken the "Best Practices for Handling Exceptions" says if you can check for an error that will likely occur then check for that condition. If you can check for dbnull then do so.
如果我没有记错的话，“处理异常的最佳实践”说您是否可以检查可能发生的错误，然后检查该条件。如果您可以检查 dbnull，请执行此操作。
回答by R.Alonso
In VB.NET you can use VISUAL BASIC 6.0 Code:
在 VB.NET 中，您可以使用 VISUAL BASIC 6.0 代码：
PRIVATE SUB PROCESO
ON ERROR GOTO VERERROR:
10: line1
20: line2
30: line3
EXIT SUB
VERERROR:
MSGBOX("ERROR " & ERR.NUM & "." & ERR.DESCRIPTION)
RESUME NEXT
'RESUME FOR RETRY
END SUB
And you can use ERL() for view err line writer before of code '10:' (o no write this numbers/labels)
您可以使用 ERL() 在代码 '10:' 之前查看错误行编写器（不要写这个数字/标签）
回答by davis
quite an old post but for the sake of others . personally i would use "on error resume next" in this case it is a necessary evil
很旧的帖子，但为了别人。在这种情况下，我个人会使用“下一个错误恢复”，这是一种必要的邪恶
