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BackgroundWorker.RunWorkerCompleted Event

Occurs when the background operation has completed, has been canceled, or has raised an exception.

Namespace:  System.ComponentModel
Assembly:  System (in System.dll)

JScript does not support events.

This event is raised when the DoWork event handler returns.

If the operation completes successfully and its result is assigned in the DoWork event handler, you can access the result through the RunWorkerCompletedEventArgs.Result property.

The Error property of System.ComponentModel.RunWorkerCompletedEventArgs indicates that an exception was thrown by the operation.

The Cancelled property of System.ComponentModel.RunWorkerCompletedEventArgs indicates whether a cancellation request was processed by the background operation. If your code in the DoWork event handler detects a cancellation request by checking the CancellationPending flag and setting the Cancel flag of System.ComponentModel.DoWorkEventArgs to true, the Cancelled flag of System.ComponentModel.RunWorkerCompletedEventArgs also will be set to true.

Caution noteCaution:

Be aware that your code in the DoWork event handler may finish its work as a cancellation request is being made, and your polling loop may miss CancellationPending being set to true. In this case, the Cancelled flag of System.ComponentModel.RunWorkerCompletedEventArgs in your RunWorkerCompleted event handler will not be set to true, even though a cancellation request was made. This situation is called a race condition and is a common concern in multithreaded programming. For more information about multithreading design issues, see Managed Threading Best Practices.

Your RunWorkerCompleted event handler should always check the AsyncCompletedEventArgs.Error and AsyncCompletedEventArgs.Cancelled properties before accessing the RunWorkerCompletedEventArgs.Result property. If an exception was raised or if the operation was canceled, accessing the RunWorkerCompletedEventArgs.Result property raises an exception.

The following code example demonstrates the use of the RunWorkerCompleted event to handle the result of an asynchronous operation. This code example is part of a larger example provided for the BackgroundWorker class.

No code example is currently available or this language may not be supported.

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0

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