ErrorEventArgs-Klasse

Stellt Daten für das Error-Ereignis bereit.

Namespace: System.IO
Assembly: System (in system.dll)

Syntax

'Declaration
Public Class ErrorEventArgs
    Inherits EventArgs
'Usage
Dim instance As ErrorEventArgs

public class ErrorEventArgs : EventArgs

public ref class ErrorEventArgs : public EventArgs

public class ErrorEventArgs extends EventArgs

public class ErrorEventArgs extends EventArgs

Hinweise

ErrorEventArgs enthält die Exception, die das Error-Ereignis ausgelöst hat. Diese Klasse stellt die GetException-Methode zum Abrufen der Ausnahme bereit.

Beispiel

Im folgenden Beispiel wird eine neue Instanz von ErrorEventArgs erstellt und mit einer Exception initialisiert. Anschließend wird im Beispiel GetException aufgerufen, um die Exception abzurufen und die Fehlermeldung anzuzeigen. Diesem Code ist kein Formular zugeordnet.

Overloads Public Shared Sub Main(args() As String)
    ' Creates an exception with an error message.
    Dim myException As New Exception("This is an exception test")
    
    ' Creates an ErrorEventArgs with the exception.
    Dim myErrorEventArgs As New ErrorEventArgs(myException)
    
    ' Extracts the exception from the ErrorEventArgs and display it.
    Dim myReturnedException As Exception = myErrorEventArgs.GetException()
    MessageBox.Show(("The returned exception is: " & myReturnedException.Message))
End Sub 'Main

public static void Main(string[] args) {
    // Creates an exception with an error message.
    Exception myException= new Exception("This is an exception test");
 
    // Creates an ErrorEventArgs with the exception.
    ErrorEventArgs myErrorEventArgs = new ErrorEventArgs(myException);
 
    // Extracts the exception from the ErrorEventArgs and display it.
    Exception myReturnedException = myErrorEventArgs.GetException();
    MessageBox.Show("The returned exception is: " + myReturnedException.Message);
 }
    

int main()
{
   
   // Creates an exception with an error message.
   Exception^ myException = gcnew Exception( "This is an exception test" );
   
   // Creates an ErrorEventArgs with the exception.
   ErrorEventArgs^ myErrorEventArgs = gcnew ErrorEventArgs( myException );
   
   // Extracts the exception from the ErrorEventArgs and display it.
   Exception^ myReturnedException = myErrorEventArgs->GetException();
   MessageBox::Show( String::Concat( "The returned exception is: ", myReturnedException->Message ) );
}

public static void main(String[] args)
{
    // Creates an exception with an error message.
    Exception myException = new Exception("This is an exception test");

    // Creates an ErrorEventArgs with the exception.
    ErrorEventArgs myErrorEventArgs = new ErrorEventArgs(myException);

    // Extracts the exception from the ErrorEventArgs and display it.
    System.Exception myReturnedException = 
        myErrorEventArgs.GetException();

    MessageBox.Show("The returned exception is: " 
        + myReturnedException.get_Message());
} //main

Im folgenden Beispiel wird die Erstellung einer FileSystemWatcher-Komponente veranschaulicht, mit der Dateiänderungen (Erstellen, Löschen, Umbenennen, Änderungen) auf einem Laufwerk überwacht werden sollen. Im Beispiel wird auch veranschaulicht, wie Fehlerbenachrichtigungen ordnungsgemäß empfangen werden.

Imports System.IO

Module Module1
    Sub Main()
        ' Create a FileSystemWatcher to monitor all files on drive C.
        Dim fsw As New FileSystemWatcher("C:\")

        ' Watch for changes in LastAccess and LastWrite times, and
        ' the renaming of files or directories. 
        fsw.NotifyFilter = (NotifyFilters.LastAccess Or NotifyFilters.LastWrite _ 
            Or NotifyFilters.FileName Or NotifyFilters.DirectoryName)

        ' Register a handler that gets called when a 
        ' file is created, changed, or deleted.
        AddHandler fsw.Changed, New FileSystemEventHandler(AddressOf OnChanged)

        ' The commented line of code below is a shorthand of the above line.
        ' AddHandler fsw.Changed, AddressOf OnChanged

        ' NOTE: The shorthand version is used in the remainder of this code.
        ' FileSystemEventHandler
        AddHandler fsw.Created, AddressOf OnChanged 
        ' FileSystemEventHandler
        AddHandler fsw.Deleted, AddressOf OnChanged

        ' Register a handler that gets called when a file is renamed.
        ' RenamedEventHandler
        AddHandler fsw.Renamed, AddressOf OnRenamed

        ' Register a handler that gets called if the 
        ' FileSystemWatcher needs to report an error.
        ' ErrorEventHandler
        AddHandler fsw.Error, AddressOf OnError

        ' Begin watching.
        fsw.EnableRaisingEvents = True

        ' Wait for the user to quit the program.
        Console.WriteLine("Press 'Enter' to quit the sample.")
        Console.ReadLine()
    End Sub

    ' This method is called when a file is created, changed, or deleted.
    Private Sub OnChanged(ByVal source As Object, ByVal e As FileSystemEventArgs)

        ' Show that a file has been created, changed, or deleted.
        Dim wct As WatcherChangeTypes = e.ChangeType
        Console.WriteLine("File {0} {1}", e.FullPath, wct.ToString())
    End Sub

    ' This method is called when a file is renamed.
    Private Sub OnRenamed(ByVal source As Object, ByVal e As RenamedEventArgs)

        ' Show that a file has been renamed.
        Dim wct As WatcherChangeTypes = e.ChangeType
        Console.WriteLine("File {0} {2} to {1}", e.OldFullPath, e.FullPath, wct.ToString())
    End Sub

    ' This method is called when the FileSystemWatcher detects an error.
    Private Sub OnError(ByVal source As Object, ByVal e As ErrorEventArgs)

        ' Show that an error has been detected.
        Console.WriteLine("The FileSystemWatcher has detected an error")

        ' Give more information if the error is due to an internal buffer overflow.
        If TypeOf e.GetException Is InternalBufferOverflowException Then
            ' This can happen if Windows is reporting many file system events quickly 
            ' and internal buffer of the  FileSystemWatcher is not large enough to handle this
            ' rate of events. The InternalBufferOverflowException error informs the application
            ' that some of the file system events are being lost.
            Console.WriteLine( _
                "The file system watcher experienced an internal buffer overflow: " _
                + e.GetException.Message)
        End If
    End Sub
End Module

Vererbungshierarchie

System.Object
   System.EventArgs
    System.IO.ErrorEventArgs

Threadsicherheit

Alle öffentlichen statischen (Shared in Visual Basic) Member dieses Typs sind threadsicher. Bei Instanzmembern ist die Threadsicherheit nicht gewährleistet.

Plattformen

Windows 98, Windows 2000 SP4, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

.NET Framework unterstützt nicht alle Versionen sämtlicher Plattformen. Eine Liste der unterstützten Versionen finden Sie unter Systemanforderungen.

Versionsinformationen

.NET Framework

Unterstützt in: 2.0, 1.1, 1.0

Siehe auch

Referenz

ErrorEventArgs-Member
System.IO-Namespace
ErrorEventHandler
FileSystemWatcher
OnError