Metodo Exception.GetBaseException (System)

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Riferimento a .NET Framework
Metodo Exception.GetBaseException

Se utilizzato come metodo di override in una classe derivata, restituisce l'Exception che è la causa principale di una o più eccezioni successive.

Spazio dei nomi: System
Assembly: mscorlib (in mscorlib.dll)

Sintassi

Visual Basic - (Dichiarazione)
Public Overridable Function GetBaseException As Exception
Visual Basic (Utilizzo)
Dim instance As Exception
Dim returnValue As Exception

returnValue = instance.GetBaseException
C#
public virtual Exception GetBaseException ()
C++
public:
virtual Exception^ GetBaseException ()
J#
public Exception GetBaseException ()
JScript
public function GetBaseException () : Exception

Valore restituito

Eccezione generata per prima in una catena di eccezioni. Se la proprietà InnerException dell'eccezione corrente è un riferimento null (Nothing in Visual Basic), restituisce l'eccezione corrente.
Note

Una catena di eccezioni consiste di un insieme di eccezioni in cui ogni eccezione nella catena viene generata quale risultato diretto dell'eccezione a cui si fa riferimento nella proprietà InnerException della prima eccezione. Per una determinata catena, può essere presente esattamente un'eccezione che è la causa principale di tutte le altre eccezioni nella catena. Questa eccezione viene detta eccezione base e la sua proprietà InnerException contiene sempre un riferimento null.

Per tutte le eccezioni in una catena di eccezioni, il metodo GetBaseException deve restituire lo stesso oggetto, ovvero l'eccezione base.

Utilizzare il metodo GetBaseException se si desidera trovare la causa principale di un'eccezione, ma non sono necessarie informazioni relative alle eccezioni che possono essere state generate tra l'eccezione corrente e la prima eccezione.

Note sull'ereditarietà: Il metodo GetBaseException viene sottoposto a override nelle classi che richiedono il controllo del contenuto e del formato dell'eccezione.

Esempio

Nell'esempio di codice riportato di seguito vengono definite due classi Exception derivate. Viene imposta un'eccezione che viene nuovamente generata con ognuna delle classi derivate. Nel codice viene illustrato come utilizzare il metodo GetBaseException per recuperare l'eccezione originale.

Visual Basic
' Example for the Exception.GetBaseException method.
Imports System
Imports Microsoft.VisualBasic

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 ' New
    End Class ' SecondLevelException

    Class ThirdLevelException
        Inherits Exception
           
        Public Sub New( message As String, inner As Exception )
            MyBase.New( message, inner )
        End Sub ' New
    End Class ' ThirdLevelException

    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 ' Main
           
        ' 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 ' Rethrow
           
        ' 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 ' DivideBy0
    End Class ' NestedExceptions
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()

C#
// 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()
*/

C++
// 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()
*/

J#
// Example for the Exception.GetBaseException method.
package NDP_UE_JSL; 

import System.* ;

// Define two derived exceptions to demonstrate nested exceptions.
class SecondLevelException extends System.Exception
{
    public SecondLevelException(String message, System.Exception inner)
    {
        super(message, inner);
    } //SecondLevelException
} //SecondLevelException

class ThirdLevelException extends System.Exception
{
    public ThirdLevelException(String message, System.Exception inner)
    {
        super(message, inner);
    } //ThirdLevelException
} //ThirdLevelException

class NestedExceptions
{
    public static void main(String[] args)
    {
        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 (System.Exception ex) {
            System.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.get_InnerException();
            }

            // Display the innermost exception.
            Console.WriteLine(("Display the base exception " 
                + "using the GetBaseException method:\n"));
            Console.WriteLine(ex.GetBaseException().ToString());
        }
    } //main

    // This function catches the exception from the called 
    // function DivideBy0( ) and throws another in response.
    static void Rethrow() throws ThirdLevelException ,SecondLevelException
    {
        try {
            DivideBy0();
        }
        catch (System.Exception ex) {
            throw new ThirdLevelException("Caught the second exception and " 
                + "threw a third in response.", ex);
        }
    } //Rethrow

    // This function forces a division by 0 and throws a second 
    // exception.
    static void DivideBy0() throws SecondLevelException
    {
        try {
            int zero = 0;
            int ecks = 1 / zero;
        }
        catch (System.Exception ex) {
            throw new SecondLevelException(
                "Forced a division by 0 and threw " 
                + "a second exception.", ex);
        }
    } //DivideBy0
} //NestedExceptions
   
/*
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_JSL.ThirdLevelException: Caught the second exception and threw a third in
 response. ---> NDP_UE_JSL.SecondLevelException: Forced a division by 0 and thre
w a second exception. ---> System.DivideByZeroException: Attempted to divide by
zero.
   at NDP_UE_JSL.NestedExceptions.DivideBy0() in C:\Documents and Settings\
   My Documents\Visual Studio Projects\ConsoleApp - JS\ConsoleApp - JS\
Class1.jsl:line 79
   --- End of inner exception stack trace ---
   at NDP_UE_JSL.NestedExceptions.DivideBy0() in C:\Documents and Settings\
   My Documents\Visual Studio Projects\ConsoleApp - JS\ConsoleApp - JS\
Class1.jsl:line 82
   at NDP_UE_JSL.NestedExceptions.Rethrow() in C:\Documents and Settings\
   My Documents\Visual Studio Projects\ConsoleApp - JS\ConsoleApp - JS\Cl
ass1.jsl:line 65
   --- End of inner exception stack trace ---
   at NDP_UE_JSL.NestedExceptions.Rethrow() in C:\Documents and Settings\
   My Documents\Visual Studio Projects\ConsoleApp - JS\ConsoleApp - JS\Cl
ass1.jsl:line 68
   at NDP_UE_JSL.NestedExceptions.main(String[] args) in C:\Documents and 
Settings\My Documents\Visual Studio Projects\ConsoleApp - JS\ConsoleA
pp - JS\Class1.jsl:line 36

NDP_UE_JSL.SecondLevelException: Forced a division by 0 and threw a second 
exception. ---> System.DivideByZeroException: Attempted to divide by zero.
   at NDP_UE_JSL.NestedExceptions.DivideBy0() in C:\Documents and Settings\
   My Documents\Visual Studio Projects\ConsoleApp - JS\ConsoleApp - JS\
Class1.jsl:line 79
   --- End of inner exception stack trace ---
   at NDP_UE_JSL.NestedExceptions.DivideBy0() in C:\Documents and Settings\
   My Documents\Visual Studio Projects\ConsoleApp - JS\ConsoleApp - JS\
Class1.jsl:line 82
   at NDP_UE_JSL.NestedExceptions.Rethrow() in C:\Documents and Settings\
   My Documents\Visual Studio Projects\ConsoleApp - JS\ConsoleApp - JS\Cl
ass1.jsl:line 65

System.DivideByZeroException: Attempted to divide by zero.
   at NDP_UE_JSL.NestedExceptions.DivideBy0() in C:\Documents and Settings\
   My Documents\Visual Studio Projects\ConsoleApp - JS\ConsoleApp - JS\
Class1.jsl:line 79

Display the base exception using the GetBaseException method:

System.DivideByZeroException: Attempted to divide by zero.
   at NDP_UE_JSL.NestedExceptions.DivideBy0() in C:\Documents and Settings\
   My Documents\Visual Studio Projects\ConsoleApp - JS\ConsoleApp - JS\
Class1.jsl:line 79
*/

Piattaforme

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile per Pocket PC, Windows Mobile per Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

.NET Framework non supporta tutte le versioni di ciascuna piattaforma. Per un elenco delle versioni supportate, vedere Requisiti di sistema.

Informazioni sulla versione

.NET Framework

Supportato in: 2.0 1.1 1.0

.NET Compact Framework

Supportato in: 2.0 1.0
Vedere anche