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RunWorkerCompletedEventArgs.Result Eigenschaft

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Definition

Namespace:
System.ComponentModel
Assemblys:
System.dll, System.ComponentModel.EventBasedAsync.dll
Assembly:
System.ComponentModel.EventBasedAsync.dll
Assembly:
System.dll
Assembly:
netstandard.dll
Quelle:
RunWorkerCompletedEvent.cs
Quelle:
RunWorkerCompletedEvent.cs
Quelle:
RunWorkerCompletedEvent.cs

Ruft einen Wert ab, der das Ergebnis eines asynchronen Vorgangs darstellt.

public:
 property System::Object ^ Result { System::Object ^ get(); };
public object Result { get; }
public object? Result { get; }
member this.Result : obj
Public ReadOnly Property Result As Object

Eigenschaftswert

Object

Ein Object, das das Ergebnis eines asynchronen Vorgangs darstellt.

Ausnahmen

TargetInvocationException

Error ist nicht null. Die InnerException-Eigenschaft enthält einen Verweis auf Error.

InvalidOperationException

Cancelled ist true.

Beispiele

Im folgenden Codebeispiel wird die Verwendung des -Ereignisses RunWorkerCompleted zum Behandeln des Ergebnisses eines asynchronen Vorgangs veranschaulicht. Dieses Codebeispiel ist Teil eines größeren Beispiels, das für die BackgroundWorker-Klasse bereitgestellt wird.

// This event handler deals with the results of the
// background operation.
void backgroundWorker1_RunWorkerCompleted( Object^ /*sender*/, RunWorkerCompletedEventArgs^ e )
{
   // First, handle the case where an exception was thrown.
   if ( e->Error != nullptr )
   {
      MessageBox::Show( e->Error->Message );
   }
   else
   if ( e->Cancelled )
   {
      // Next, handle the case where the user cancelled 
      // the operation.
      // Note that due to a race condition in 
      // the DoWork event handler, the Cancelled
      // flag may not have been set, even though
      // CancelAsync was called.
      resultLabel->Text = "Cancelled";
   }
   else
   {
      // Finally, handle the case where the operation 
      // succeeded.
      resultLabel->Text = e->Result->ToString();
   }

   // Enable the UpDown control.
   this->numericUpDown1->Enabled = true;

   // Enable the Start button.
   startAsyncButton->Enabled = true;

   // Disable the Cancel button.
   cancelAsyncButton->Enabled = false;
}

// This event handler deals with the results of the
// background operation.
private void backgroundWorker1_RunWorkerCompleted(
    object sender, RunWorkerCompletedEventArgs e)
{
    // First, handle the case where an exception was thrown.
    if (e.Error != null)
    {
        MessageBox.Show(e.Error.Message);
    }
    else if (e.Cancelled)
    {
        // Next, handle the case where the user canceled 
        // the operation.
        // Note that due to a race condition in 
        // the DoWork event handler, the Cancelled
        // flag may not have been set, even though
        // CancelAsync was called.
        resultLabel.Text = "Canceled";
    }
    else
    {
        // Finally, handle the case where the operation 
        // succeeded.
        resultLabel.Text = e.Result.ToString();
    }

    // Enable the UpDown control.
    this.numericUpDown1.Enabled = true;

    // Enable the Start button.
    startAsyncButton.Enabled = true;

    // Disable the Cancel button.
    cancelAsyncButton.Enabled = false;
}

' This event handler deals with the results of the
' background operation.
Private Sub backgroundWorker1_RunWorkerCompleted( _
ByVal sender As Object, ByVal e As RunWorkerCompletedEventArgs) _
Handles backgroundWorker1.RunWorkerCompleted

    ' First, handle the case where an exception was thrown.
    If (e.Error IsNot Nothing) Then
        MessageBox.Show(e.Error.Message)
    ElseIf e.Cancelled Then
        ' Next, handle the case where the user canceled the 
        ' operation.
        ' Note that due to a race condition in 
        ' the DoWork event handler, the Cancelled
        ' flag may not have been set, even though
        ' CancelAsync was called.
        resultLabel.Text = "Canceled"
    Else
        ' Finally, handle the case where the operation succeeded.
        resultLabel.Text = e.Result.ToString()
    End If

    ' Enable the UpDown control.
    Me.numericUpDown1.Enabled = True

    ' Enable the Start button.
    startAsyncButton.Enabled = True

    ' Disable the Cancel button.
    cancelAsyncButton.Enabled = False
End Sub

Hinweise

Ihr RunWorkerCompleted Ereignishandler sollte immer die Error Eigenschaften und Cancelled überprüfen, bevor auf die Result Eigenschaft zugegriffen wird. Wenn eine Ausnahme ausgelöst wurde oder der Vorgang abgebrochen wurde, löst der Zugriff auf die Result -Eigenschaft eine Ausnahme aus.

Gilt für:

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