Exception.GetBaseException Methode
Definition
Wichtig
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Gibt beim Überschreiben in einer abgeleiteten Klasse eine Exception zurück, die die Grundursache für eine oder mehrere nachfolgende Ausnahmen ist.
public:
virtual Exception ^ GetBaseException();public virtual Exception GetBaseException ();abstract member GetBaseException : unit -> Exception
override this.GetBaseException : unit -> ExceptionPublic Overridable Function GetBaseException () As ExceptionGibt zurück
Die erste Ausnahme, die in einer Kette von Ausnahmen ausgelöst wird. Wenn die InnerException-Eigenschaft der aktuellen Ausnahme ein NULL-Verweis (Nothing in Visual Basic) ist, gibt diese Eigenschaft die aktuelle Ausnahme zurück.
Implementiert
Beispiele
Im folgenden Codebeispiel werden zwei abgeleitete Exception Klassen definiert. Es erzwingt eine Ausnahme und löst sie dann erneut mit jeder abgeleiteten Klasse aus. Der Code zeigt die Verwendung der Methode zum Abrufen der GetBaseException ursprünglichen Ausnahme.
// Example for the Exception::GetBaseException method.
using namespace System;
namespace NDP_UE_CPP
{
// Define two derived exceptions to demonstrate nested exceptions.
ref class SecondLevelException: public Exception
{
public:
SecondLevelException( String^ message, Exception^ inner )
: Exception( message, inner )
{}
};
ref class ThirdLevelException: public Exception
{
public:
ThirdLevelException( String^ message, Exception^ inner )
: Exception( message, inner )
{}
};
// DivideBy0 forces a division by 0 and throws a second exception.
void DivideBy0()
{
try
{
int zero = 0;
int ecks = 1 / zero;
}
catch ( Exception^ ex )
{
throw gcnew SecondLevelException( "Forced a division by 0 and threw "
"a second exception.",ex );
}
}
// This function catches the exception from the called function
// DivideBy0( ) and throws another in response.
void Rethrow()
{
try
{
DivideBy0();
}
catch ( Exception^ ex )
{
throw gcnew ThirdLevelException( "Caught the second exception and "
"threw a third in response.",ex );
}
}
}
int main()
{
Console::WriteLine( "This example of Exception.GetBaseException "
"generates the following output." );
Console::WriteLine( "\nThe program forces a division by 0, "
"then throws the exception \ntwice more, "
"using a different derived exception each time.\n" );
try
{
// This function calls another that forces a division by 0.
NDP_UE_CPP::Rethrow();
}
catch ( Exception^ e )
{
Exception^ current;
Console::WriteLine( "Unwind the nested exceptions using "
"the InnerException property:\n" );
// This code unwinds the nested exceptions using the
// InnerException property.
current = e;
while ( current != (Object^)0 )
{
Console::WriteLine( current->ToString() );
Console::WriteLine();
current = current->InnerException;
}
// Display the innermost exception.
Console::WriteLine( "Display the base exception using the \n"
"GetBaseException method:\n" );
Console::WriteLine( e->GetBaseException()->ToString() );
}
}
/*
This example of Exception.GetBaseException generates the following output.
The program forces a division by 0, then throws the exception
twice more, using a different derived exception each time.
Unwind the nested exceptions using the InnerException property:
NDP_UE_CPP.ThirdLevelException: Caught the second exception and threw a third i
n response. ---> NDP_UE_CPP.SecondLevelException: Forced a division by 0 and th
rew a second exception. ---> System.DivideByZeroException: Attempted to divide
by zero.
at NDP_UE_CPP.DivideBy0()
--- End of inner exception stack trace ---
at NDP_UE_CPP.DivideBy0()
at NDP_UE_CPP.Rethrow()
--- End of inner exception stack trace ---
at NDP_UE_CPP.Rethrow()
at main()
NDP_UE_CPP.SecondLevelException: Forced a division by 0 and threw a second exce
ption. ---> System.DivideByZeroException: Attempted to divide by zero.
at NDP_UE_CPP.DivideBy0()
--- End of inner exception stack trace ---
at NDP_UE_CPP.DivideBy0()
at NDP_UE_CPP.Rethrow()
System.DivideByZeroException: Attempted to divide by zero.
at NDP_UE_CPP.DivideBy0()
Display the base exception using the
GetBaseException method:
System.DivideByZeroException: Attempted to divide by zero.
at NDP_UE_CPP.DivideBy0()
*/
// Example for the Exception.GetBaseException method.
using System;
namespace NDP_UE_CS
{
// Define two derived exceptions to demonstrate nested exceptions.
class SecondLevelException : Exception
{
public SecondLevelException( string message, Exception inner )
: base( message, inner )
{ }
}
class ThirdLevelException : Exception
{
public ThirdLevelException( string message, Exception inner )
: base( message, inner )
{ }
}
class NestedExceptions
{
public static void Main()
{
Console.WriteLine(
"This example of Exception.GetBaseException " +
"generates the following output." );
Console.WriteLine(
"\nThe program forces a division by 0, then " +
"throws the exception \ntwice more, " +
"using a different derived exception each time.\n" );
try
{
// This function calls another that forces a
// division by 0.
Rethrow( );
}
catch( Exception ex )
{
Exception current;
Console.WriteLine(
"Unwind the nested exceptions " +
"using the InnerException property:\n" );
// This code unwinds the nested exceptions using the
// InnerException property.
current = ex;
while( current != null )
{
Console.WriteLine( current.ToString( ) );
Console.WriteLine( );
current = current.InnerException;
}
// Display the innermost exception.
Console.WriteLine(
"Display the base exception " +
"using the GetBaseException method:\n" );
Console.WriteLine(
ex.GetBaseException( ).ToString( ) );
}
}
// This function catches the exception from the called
// function DivideBy0( ) and throws another in response.
static void Rethrow()
{
try
{
DivideBy0( );
}
catch( Exception ex )
{
throw new ThirdLevelException(
"Caught the second exception and " +
"threw a third in response.", ex );
}
}
// This function forces a division by 0 and throws a second
// exception.
static void DivideBy0( )
{
try
{
int zero = 0;
int ecks = 1 / zero;
}
catch( Exception ex )
{
throw new SecondLevelException(
"Forced a division by 0 and threw " +
"a second exception.", ex );
}
}
}
}
/*
This example of Exception.GetBaseException generates the following output.
The program forces a division by 0, then throws the exception
twice more, using a different derived exception each time.
Unwind the nested exceptions using the InnerException property:
NDP_UE_CS.ThirdLevelException: Caught the second exception and threw a third in
response. ---> NDP_UE_CS.SecondLevelException: Forced a division by 0 and thre
w a second exception. ---> System.DivideByZeroException: Attempted to divide by
zero.
at NDP_UE_CS.NestedExceptions.DivideBy0()
--- End of inner exception stack trace ---
at NDP_UE_CS.NestedExceptions.DivideBy0()
at NDP_UE_CS.NestedExceptions.Rethrow()
--- End of inner exception stack trace ---
at NDP_UE_CS.NestedExceptions.Rethrow()
at NDP_UE_CS.NestedExceptions.Main()
NDP_UE_CS.SecondLevelException: Forced a division by 0 and threw a second excep
tion. ---> System.DivideByZeroException: Attempted to divide by zero.
at NDP_UE_CS.NestedExceptions.DivideBy0()
--- End of inner exception stack trace ---
at NDP_UE_CS.NestedExceptions.DivideBy0()
at NDP_UE_CS.NestedExceptions.Rethrow()
System.DivideByZeroException: Attempted to divide by zero.
at NDP_UE_CS.NestedExceptions.DivideBy0()
Display the base exception using the GetBaseException method:
System.DivideByZeroException: Attempted to divide by zero.
at NDP_UE_CS.NestedExceptions.DivideBy0()
*/
// Example for the Exception.GetBaseException method.
open System
// Define two derived exceptions to demonstrate nested exceptions.
type SecondLevelException(message, inner: Exception) =
inherit Exception(message, inner)
type ThirdLevelException(message, inner: Exception) =
inherit Exception(message, inner)
printfn
"""This example of Exception.GetBaseException generates the following output.
The program forces a division by 0, then throws the exception
twice more, using a different derived exception each time.
"""
// This function forces a division by 0 and throws a second exception.
let divideBy0 () =
try
let zero = 0
let ecks = 1 / zero
()
with ex ->
raise (SecondLevelException("Forced a division by 0 and threw a second exception.", ex) )
// This function catches the exception from the called
// function divideBy0() and throws another in response.
let rethrow () =
try
divideBy0 ()
with ex ->
raise (ThirdLevelException("Caught the second exception and threw a third in response.", ex) )
try
// This function calls another that forces a
// division by 0.
rethrow ()
with ex ->
printfn "Unwind the nested exceptions using the InnerException property:\n"
// This code unwinds the nested exceptions using the
// InnerException property.
let mutable current = ex
while current <> null do
printfn $"{current}\n"
current <- current.InnerException
// Display the innermost exception.
printfn "Display the base exception using the GetBaseException method:\n"
printfn $"{ex.GetBaseException()}"
// This example of Exception.GetBaseException generates the following output.
//
// The program forces a division by 0, then throws the exception
// twice more, using a different derived exception each time.
//
// Unwind the nested exceptions using the InnerException property:
//
// NDP_UE_FS+ThirdLevelException: Caught the second exception and threw a third in
// response. ---> NDP_UE_FS.SecondLevelException: Forced a division by 0 and thre
// w a second exception. ---> System.DivideByZeroException: Attempted to divide by
// zero.
// at NDP_UE_FS.divideBy0()
// --- End of inner exception stack trace ---
// at NDP_UE_FS.divideBy0()
// at NDP_UE_FS.rethrow()
// --- End of inner exception stack trace ---
// at NDP_UE_FS.rethrow()
// at<StartupCode$fs>.$NDP_UE_FS.main@()
//
// NDP_UE_FS.SecondLevelException: Forced a division by 0 and threw a second excep
// tion. ---> System.DivideByZeroException: Attempted to divide by zero.
// at NDP_UE_FS.divideBy0()
// --- End of inner exception stack trace ---
// at NDP_UE_FS.divideBy0()
// at NDP_UE_FS.rethrow()
//
// System.DivideByZeroException: Attempted to divide by zero.
// at NDP_UE_FS.divideBy0()
//
// Display the base exception using the GetBaseException method:
//
// System.DivideByZeroException: Attempted to divide by zero.
// at NDP_UE_FS.divideBy0()
' Example for the Exception.GetBaseException method.
Namespace NDP_UE_VB
' Define two derived exceptions to demonstrate nested exceptions.
Class SecondLevelException
Inherits Exception
Public Sub New( message As String, inner As Exception )
MyBase.New( message, inner )
End Sub
End Class
Class ThirdLevelException
Inherits Exception
Public Sub New( message As String, inner As Exception )
MyBase.New( message, inner )
End Sub
End Class
Class NestedExceptions
Public Shared Sub Main( )
Console.WriteLine( _
"This example of Exception.GetBaseException " & _
"generates the following output." )
Console.WriteLine( vbCrLf & _
"The program forces a division by 0, then throws " & _
"the exception " & vbCrLf & "twice more, using " & _
"a different derived exception each time:" & vbCrLf )
Try
' This sub calls another that forces a division by 0.
Rethrow()
Catch ex As Exception
Dim current As Exception
Console.WriteLine( _
"Unwind the nested exceptions using the " & _
"InnerException property:" & vbCrLf )
' This code unwinds the nested exceptions using the
' InnerException property.
current = ex
While Not ( current Is Nothing )
Console.WriteLine( current.ToString( ) )
Console.WriteLine( )
current = current.InnerException
End While
' Display the innermost exception.
Console.WriteLine( _
"Display the base exception using the " & _
"GetBaseException method:" & vbCrLf )
Console.WriteLine( _
ex.GetBaseException( ).ToString( ) )
End Try
End Sub
' This sub catches the exception from the called sub
' DivideBy0( ) and throws another in response.
Shared Sub Rethrow( )
Try
DivideBy0( )
Catch ex As Exception
Throw New ThirdLevelException( _
"Caught the second exception and " & _
"threw a third in response.", ex )
End Try
End Sub
' This sub forces a division by 0 and throws a second
' exception.
Shared Sub DivideBy0( )
Try
Dim zero As Integer = 0
Dim ecks As Integer = 1 \ zero
Catch ex As Exception
Throw New SecondLevelException( _
"Forced a division by 0 and threw " & _
"a second exception.", ex )
End Try
End Sub
End Class
End Namespace ' NDP_UE_VB
' This example of Exception.GetBaseException generates the following output.
'
' The program forces a division by 0, then throws the exception
' twice more, using a different derived exception each time:
'
' Unwind the nested exceptions using the InnerException property:
'
' NDP_UE_VB.ThirdLevelException: Caught the second exception and threw a third
' in response. ---> NDP_UE_VB.SecondLevelException: Forced a division by 0 and
' threw a second exception. ---> System.DivideByZeroException: Attempted to div
' ide by zero.
' at NDP_UE_VB.NestedExceptions.DivideBy0()
' --- End of inner exception stack trace ---
' at NDP_UE_VB.NestedExceptions.DivideBy0()
' at NDP_UE_VB.NestedExceptions.Rethrow()
' --- End of inner exception stack trace ---
' at NDP_UE_VB.NestedExceptions.Rethrow()
' at NDP_UE_VB.NestedExceptions.Main()
'
' NDP_UE_VB.SecondLevelException: Forced a division by 0 and threw a second exc
' eption. ---> System.DivideByZeroException: Attempted to divide by zero.
' at NDP_UE_VB.NestedExceptions.DivideBy0()
' --- End of inner exception stack trace ---
' at NDP_UE_VB.NestedExceptions.DivideBy0()
' at NDP_UE_VB.NestedExceptions.Rethrow()
'
' System.DivideByZeroException: Attempted to divide by zero.
' at NDP_UE_VB.NestedExceptions.DivideBy0()
'
' Display the base exception using the GetBaseException method:
'
' System.DivideByZeroException: Attempted to divide by zero.
' at NDP_UE_VB.NestedExceptions.DivideBy0()
Hinweise
Eine Kette von Ausnahmen besteht aus einer Reihe von Ausnahmen, sodass jede Ausnahme in der Kette als direktes Ergebnis der Ausnahme ausgelöst wurde, auf die in der InnerException Eigenschaft verwiesen wird. Bei einer bestimmten Kette kann es genau eine Ausnahme geben, die die Ursache aller anderen Ausnahmen in der Kette ist. Diese Ausnahme wird als Basis ausnahme bezeichnet, und seine InnerException Eigenschaft enthält immer einen NULL-Verweis.
Für alle Ausnahmen in einer Kette von Ausnahmen muss die GetBaseException Methode dasselbe Objekt (die Basis ausnahme) zurückgeben.
Verwenden Sie die GetBaseException Methode, wenn Sie die Ursache einer Ausnahme finden möchten, aber keine Informationen zu Ausnahmen benötigen, die zwischen der aktuellen Ausnahme und der ersten Ausnahme aufgetreten sind.
Hinweise für Vererber
Die GetBaseException Methode wird in Klassen außer Kraft gesetzt, die die Kontrolle über den Ausnahmeinhalt oder das Format erfordern.