RunWorkerCompletedEventArgs.Result Propriété

Définition

Espace de noms:

System.ComponentModel

Assembly:

System.ComponentModel.EventBasedAsync.dll

Source:

RunWorkerCompletedEvent.cs

Obtient une valeur qui représente le résultat d'une opération asynchrone.

public:
 property System::Object ^ Result { System::Object ^ get(); };

public object? Result { get; }

member this.Result : obj

Public ReadOnly Property Result As Object

Valeur de propriété

Object

Object qui représente le résultat d'une opération asynchrone.

Exceptions

TargetInvocationException

Error n’est pas un null. La propriété InnerException contient une référence à Error.

InvalidOperationException

Cancelled a la valeur true.

Exemples

L’exemple de code suivant illustre l’utilisation de l’événement RunWorkerCompleted pour gérer le résultat d’une opération asynchrone. Cet exemple de code fait partie d’un exemple plus grand fourni pour la BackgroundWorker classe .

// 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

Remarques

Votre RunWorkerCompleted gestionnaire d’événements doit toujours case activée les Error propriétés et Cancelled avant d’accéder à la Result propriété. Si une exception a été levée ou si l’opération a été annulée, l’accès à la Result propriété déclenche une exception.

Voir aussi

• BackgroundWorker
• Procédure : exécuter une opération en arrière-plan
• Procédure : télécharger un fichier en arrière-plan