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AsyncCompletedEventArgs Class

Provides data for the MethodNameCompleted event.

System.Object
  System.EventArgs
    System.ComponentModel.AsyncCompletedEventArgs
      More...

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

'Declaration
<HostProtectionAttribute(SecurityAction.LinkDemand, SharedState := True)> _
Public Class AsyncCompletedEventArgs _
	Inherits EventArgs

The AsyncCompletedEventArgs type exposes the following members.

  NameDescription
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryAsyncCompletedEventArgsInitializes a new instance of the AsyncCompletedEventArgs class.
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  NameDescription
Public propertySupported by the XNA FrameworkSupported by Portable Class LibraryCancelledGets a value indicating whether an asynchronous operation has been canceled.
Public propertySupported by the XNA FrameworkSupported by Portable Class LibraryErrorGets a value indicating which error occurred during an asynchronous operation.
Public propertySupported by the XNA FrameworkSupported by Portable Class LibraryUserStateGets the unique identifier for the asynchronous task.
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  NameDescription
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryEquals(Object)Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
Protected methodSupported by the XNA FrameworkSupported by Portable Class LibraryFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryGetHashCodeServes as a hash function for a particular type. (Inherited from Object.)
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryGetTypeGets the Type of the current instance. (Inherited from Object.)
Protected methodSupported by the XNA FrameworkSupported by Portable Class LibraryMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Protected methodSupported by the XNA FrameworkSupported by Portable Class LibraryRaiseExceptionIfNecessaryRaises a user-supplied exception if an asynchronous operation failed.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryToStringReturns a string that represents the current object. (Inherited from Object.)
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If you are using a class that implements the Event-based Asynchronous Pattern Overview, the class will provide a MethodNameCompleted event. If you add an instance of the System.ComponentModel.AsyncCompletedEventHandler delegate to the event, you will receive information about the outcome of asynchronous operations in the AsyncCompletedEventArgs parameter of the corresponding event-handler method.

The client application's event-handler delegate can check the Cancelled property to determine if the asynchronous task was cancelled.

The client application's event-handler delegate can check the Error property to determine if an exception occurred during execution of the asynchronous task.

If the class supports multiple asynchronous methods, or multiple calls to the same asynchronous method, you can determine which task raised the MethodNameCompleted event by checking the value of the UserState property. Your code will need to track these tokens, known as task IDs, as their corresponding asynchronous tasks start and complete.

NoteNote

The HostProtectionAttribute attribute applied to this type or member has the following Resources property value: SharedState. The HostProtectionAttribute does not affect desktop applications (which are typically started by double-clicking an icon, typing a command, or entering a URL in a browser). For more information, see the HostProtectionAttribute class or SQL Server Programming and Host Protection Attributes.

Notes to Inheritors

Classes that follow the Event-based Asynchronous Pattern can raise events to alert clients about the status of pending asynchronous operations. If the class provides a MethodNameCompleted event, you can use the AsyncCompletedEventArgs to tell clients about the outcome of asynchronous operations.

You may want to communicate to clients more information about the outcome of an asynchronous operation than an AsyncCompletedEventArgs accommodates. In this case, you can derive your own class from the AsyncCompletedEventArgs class and provide additional private instance variables and corresponding read-only public properties. Call the RaiseExceptionIfNecessary method before returning the property value, in case the operation was canceled or an error occurred.

The following code example demonstrates using an AsyncOperation to track the lifetime of asynchronous operations. This code example is part of a larger example provided for the System.ComponentModel.AsyncOperationManager class.


Imports System
Imports System.Collections
Imports System.Collections.Specialized
Imports System.ComponentModel
Imports System.Drawing
Imports System.Globalization
Imports System.Threading
Imports System.Windows.Forms


...


' This event handler updates the ListView control when the
' PrimeNumberCalculator raises the CalculatePrimeCompleted
' event. The ListView item is updated with the appropriate
' outcome of the calculation: Canceled, Error, or result.
Private Sub primeNumberCalculator1_CalculatePrimeCompleted( _
    ByVal sender As Object, _
    ByVal e As CalculatePrimeCompletedEventArgs) _
    Handles primeNumberCalculator1.CalculatePrimeCompleted

    Dim taskId As Guid = CType(e.UserState, Guid)

    If e.Cancelled Then
        Dim result As String = "Canceled"

        Dim lvi As ListViewItem = UpdateListViewItem( _
            taskId, _
            result)

        If (lvi IsNot Nothing) Then
            lvi.BackColor = Color.Pink
            lvi.Tag = Nothing
        End If

    ElseIf e.Error IsNot Nothing Then

        Dim result As String = "Error"

        Dim lvi As ListViewItem = UpdateListViewItem( _
            taskId, result)

        If (lvi IsNot Nothing) Then
            lvi.BackColor = Color.Red
            lvi.ForeColor = Color.White
            lvi.Tag = Nothing
        End If
    Else
        Dim result As Boolean = e.IsPrime

        Dim lvi As ListViewItem = UpdateListViewItem( _
            taskId, _
            result, _
            e.FirstDivisor)

        If (lvi IsNot Nothing) Then
            lvi.BackColor = Color.LightGray
            lvi.Tag = Nothing
        End If
    End If

End Sub


.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

System.Object
  System.EventArgs
    System.ComponentModel.AsyncCompletedEventArgs
      System.Activities.InvokeCompletedEventArgs
      System.ComponentModel.RunWorkerCompletedEventArgs
      System.Deployment.Application.CheckForUpdateCompletedEventArgs
      System.Deployment.Application.DownloadApplicationCompletedEventArgs
      System.Deployment.Application.DownloadFileGroupCompletedEventArgs
      System.Deployment.Application.GetManifestCompletedEventArgs
      System.Device.Location.ResolveAddressCompletedEventArgs
      System.Net.DownloadDataCompletedEventArgs
      System.Net.DownloadStringCompletedEventArgs
      System.Net.NetworkInformation.PingCompletedEventArgs
      System.Net.OpenReadCompletedEventArgs
      System.Net.OpenWriteCompletedEventArgs
      System.Net.PeerToPeer.Collaboration.CreateContactCompletedEventArgs
      System.Net.PeerToPeer.Collaboration.InviteCompletedEventArgs
      System.Net.PeerToPeer.Collaboration.RefreshDataCompletedEventArgs
      System.Net.PeerToPeer.Collaboration.SubscribeCompletedEventArgs
      System.Net.PeerToPeer.ResolveCompletedEventArgs
      System.Net.UploadDataCompletedEventArgs
      System.Net.UploadFileCompletedEventArgs
      System.Net.UploadStringCompletedEventArgs
      System.Net.UploadValuesCompletedEventArgs
      System.ServiceModel.ClientBase(Of TChannel).InvokeAsyncCompletedEventArgs
      System.ServiceModel.Discovery.FindCompletedEventArgs
      System.ServiceModel.Discovery.ResolveCompletedEventArgs
      System.Speech.Recognition.EmulateRecognizeCompletedEventArgs
      System.Speech.Recognition.LoadGrammarCompletedEventArgs
      System.Speech.Recognition.RecognizeCompletedEventArgs
      System.Speech.Synthesis.PromptEventArgs
      System.Web.Services.Protocols.InvokeCompletedEventArgs
      System.Windows.Documents.GetPageCompletedEventArgs
      System.Windows.Documents.GetPageNumberCompletedEventArgs
      System.Windows.Documents.GetPageRootCompletedEventArgs
      System.Windows.Documents.Serialization.WritingCompletedEventArgs
      System.Windows.Xps.Serialization.XpsSerializationCompletedEventArgs

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