Creates a continuation that executes according to the specified TaskContinuationOptions.
Namespace: System.Threading.Tasks
Assembly: mscorlib (in mscorlib.dll)
public Task ContinueWith(
Action<Task> continuationAction,
CancellationToken cancellationToken,
TaskContinuationOptions continuationOptions,
TaskScheduler scheduler
)
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.
- cancellationToken
- Type: System.Threading.CancellationToken
The CancellationToken that will be assigned to the new continuation task.
- 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.
- scheduler
- Type: System.Threading.Tasks.TaskScheduler
The TaskScheduler to associate with the continuation task and to use for its execution.
| Exception | Condition |
|---|---|
| ObjectDisposedException | The Task has been disposed. -or- The CancellationTokenSource that created the token has already been disposed. |
| ArgumentNullException | The continuationAction argument is null. -or- The scheduler argument is null. |
| ArgumentOutOfRangeException | The continuationOptions argument specifies an invalid value for TaskContinuationOptions. |
The returned Task will not be scheduled for execution until the current task has completed. If the criteria specified through the continuationOptions parameter are not met, the continuation task will be canceled instead of scheduled.
The following is an example of using ContinueWith to run work both in the background and on the user interface threads.
// C#
private void Button1_Click(object sender, EventArgs e)
{
var backgroundScheduler = TaskScheduler.Default;
var uiScheduler = TaskScheduler.FromCurrentSynchronizationContext();
Task.Factory.StartNew(delegate { DoBackgroundComputation(); }, backgroundScheduler).
ContinueWith(delegate { UpdateUI(); }, uiScheduler).
ContinueWith(delegate { DoAnotherBackgroundComputation(); }, backgroundScheduler).
ContinueWith(delegate { UpdateUIAgain(); }, uiScheduler);
}
' Visual Basic
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim backgroundScheduler = TaskScheduler.Default
Dim uiScheduler = TaskScheduler.FromCurrentSynchronizationContext()
Task.Factory.StartNew(Sub()
DoBackgroundComputation()
End Sub, backgroundScheduler).ContinueWith(Sub(t)
UpdateUI()
End Sub, uiScheduler).ContinueWith(Sub(t)
DoAnotherBackgroundComputation()
End Sub, backgroundScheduler).ContinueWith(Sub(t)
UpdateUIAgain()
End Sub, uiScheduler)
End Sub
Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
