Task.ContinueWith Method (Action<Task>, TaskContinuationOptions)
Microsoft Silverlight will reach end of support after October 2021. Learn more.
Creates a continuation that executes according to the specified TaskContinuationOptions.
Namespace: System.Threading.Tasks
Assembly: mscorlib (in mscorlib.dll)
Syntax
'Declaration
Public Function ContinueWith ( _
continuationAction As Action(Of Task), _
continuationOptions As TaskContinuationOptions _
) As Task
public Task ContinueWith(
Action<Task> continuationAction,
TaskContinuationOptions continuationOptions
)
Parameters
- continuationAction
Type: System.Action<Task>
An action to run according to the specified continuationOptions. When run, the delegate will be passed the completed task as an argument.
- continuationOptions
Type: System.Threading.Tasks.TaskContinuationOptions
Options for when the continuation is scheduled and how it behaves. This includes criteria, such as OnlyOnCanceled, as well as execution options, such as ExecuteSynchronously.
Return Value
Type: System.Threading.Tasks.Task
A new continuation Task.
Exceptions
| Exception | Condition |
|---|---|
| ObjectDisposedException | The Task has been disposed. |
| ArgumentNullException | The continuationAction argument is null. |
| ArgumentOutOfRangeException | The continuationOptions argument specifies an invalid value for TaskContinuationOptions. |
Remarks
The returned Task will not be scheduled for execution until the current task has completed. If the continuation criteria specified through the continuationOptions parameter are not met, the continuation task will be canceled instead of scheduled.
Examples
The following example demonstrates using TaskContinuationOptions to specify that a continuation task should run synchronously when the antecedent task completes. (If the specified task has already completed by the time ContinueWith is called, the synchronous continuation will run on the thread calling ContinueWith.)
// C#
public class TaskCounter
{
private volatile int _count;
public void Track(Task t)
{
if (t == null) throw new ArgumentNullException("t");
Interlocked.Increment(ref _count);
t.ContinueWith(ct => Interlocked.Decrement(ref _count), TaskContinuationOptions.ExecuteSynchronously);
}
public int NumberOfActiveTasks { get { return _count; } }
}
' Visual Basic
Public Class TaskCounter
Private _count as Integer
Public Sub Track(ByVal t as Task)
If t is Nothing Then Throw New ArgumentNullException("t")
Interlocked.Increment(_count)
t.ContinueWith(Sub(ct)
Interlocked.Decrement(_count)
End Sub, TaskContinuationOptions.ExecuteSynchronously)
End Sub
Public ReadOnly Property NumberOfActiveTasks As Integer
Get
Return _count
End Get
End Property
End Class
Version Information
Silverlight
Supported in: 5
Platforms
For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.