Task.ContinueWith Method

Reference

Definition

Namespace:: System.Threading.Tasks

Assembly:: System.Threading.Tasks.dll

Assembly:: System.Runtime.dll

Assembly:: mscorlib.dll

Assembly:: netstandard.dll

Important

Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.

Creates a continuation that executes asynchronously when the target Task completes.

Overloads

ContinueWith(Action<Task,Object>, Object, CancellationToken, TaskContinuationOptions, TaskScheduler)	Creates a continuation that receives caller-supplied state information and a cancellation token and that executes when the target Task completes. The continuation executes based on a set of specified conditions and uses a specified scheduler.
ContinueWith(Action<Task>, CancellationToken, TaskContinuationOptions, TaskScheduler)	Creates a continuation that executes when the target task competes according to the specified TaskContinuationOptions. The continuation receives a cancellation token and uses a specified scheduler.
ContinueWith(Action<Task,Object>, Object, TaskScheduler)	Creates a continuation that receives caller-supplied state information and executes asynchronously when the target Task completes. The continuation uses a specified scheduler.
ContinueWith(Action<Task,Object>, Object, TaskContinuationOptions)	Creates a continuation that receives caller-supplied state information and executes when the target Task completes. The continuation executes based on a set of specified conditions.
ContinueWith(Action<Task,Object>, Object, CancellationToken)	Creates a continuation that receives caller-supplied state information and a cancellation token and that executes asynchronously when the target Task completes.
ContinueWith(Action<Task>)	Creates a continuation that executes asynchronously when the target Task completes.
ContinueWith(Action<Task>, TaskContinuationOptions)	Creates a continuation that executes when the target task completes according to the specified TaskContinuationOptions.
ContinueWith(Action<Task>, CancellationToken)	Creates a continuation that receives a cancellation token and executes asynchronously when the target Task completes.
ContinueWith(Action<Task,Object>, Object)	Creates a continuation that receives caller-supplied state information and executes when the target Task completes.
ContinueWith(Action<Task>, TaskScheduler)	Creates a continuation that executes asynchronously when the target Task completes. The continuation uses a specified scheduler.
ContinueWith<TResult>(Func<Task,Object,TResult>, Object, TaskScheduler)	Creates a continuation that executes asynchronously when the target Task completes. The continuation receives caller-supplied state information and uses a specified scheduler.
ContinueWith<TResult>(Func<Task,Object,TResult>, Object, CancellationToken, TaskContinuationOptions, TaskScheduler)	Creates a continuation that executes based on the specified task continuation options when the target Task completes and returns a value. The continuation receives caller-supplied state information and a cancellation token and uses the specified scheduler.
ContinueWith<TResult>(Func<Task,TResult>, CancellationToken, TaskContinuationOptions, TaskScheduler)	Creates a continuation that executes according to the specified continuation options and returns a value. The continuation is passed a cancellation token and uses a specified scheduler.
ContinueWith<TResult>(Func<Task,Object,TResult>, Object, CancellationToken)	Creates a continuation that executes asynchronously when the target Task completes and returns a value. The continuation receives caller-supplied state information and a cancellation token.
ContinueWith<TResult>(Func<Task,Object,TResult>, Object, TaskContinuationOptions)	Creates a continuation that executes based on the specified task continuation options when the target Task completes. The continuation receives caller-supplied state information.
ContinueWith<TResult>(Func<Task,TResult>, TaskContinuationOptions)	Creates a continuation that executes according to the specified continuation options and returns a value.
ContinueWith<TResult>(Func<Task,TResult>, TaskScheduler)	Creates a continuation that executes asynchronously when the target Task completes and returns a value. The continuation uses a specified scheduler.
ContinueWith<TResult>(Func<Task,TResult>, CancellationToken)	Creates a continuation that executes asynchronously when the target Task completes and returns a value. The continuation receives a cancellation token.
ContinueWith<TResult>(Func<Task,Object,TResult>, Object)	Creates a continuation that receives caller-supplied state information and executes asynchronously when the target Task completes and returns a value.
ContinueWith<TResult>(Func<Task,TResult>)	Creates a continuation that executes asynchronously when the target Task<TResult> completes and returns a value.

ContinueWith(Action<Task,Object>, Object, CancellationToken, TaskContinuationOptions, TaskScheduler)

Source:: Task.cs

Source:: Task.cs

Source:: Task.cs

Creates a continuation that receives caller-supplied state information and a cancellation token and that executes when the target Task completes. The continuation executes based on a set of specified conditions and uses a specified scheduler.

public:
 System::Threading::Tasks::Task ^ ContinueWith(Action<System::Threading::Tasks::Task ^, System::Object ^> ^ continuationAction, System::Object ^ state, System::Threading::CancellationToken cancellationToken, System::Threading::Tasks::TaskContinuationOptions continuationOptions, System::Threading::Tasks::TaskScheduler ^ scheduler);

public System.Threading.Tasks.Task ContinueWith (Action<System.Threading.Tasks.Task,object> continuationAction, object state, System.Threading.CancellationToken cancellationToken, System.Threading.Tasks.TaskContinuationOptions continuationOptions, System.Threading.Tasks.TaskScheduler scheduler);

public System.Threading.Tasks.Task ContinueWith (Action<System.Threading.Tasks.Task,object?> continuationAction, object? state, System.Threading.CancellationToken cancellationToken, System.Threading.Tasks.TaskContinuationOptions continuationOptions, System.Threading.Tasks.TaskScheduler scheduler);

member this.ContinueWith : Action<System.Threading.Tasks.Task, obj> * obj * System.Threading.CancellationToken * System.Threading.Tasks.TaskContinuationOptions * System.Threading.Tasks.TaskScheduler -> System.Threading.Tasks.Task

Public Function ContinueWith (continuationAction As Action(Of Task, Object), state As Object, cancellationToken As CancellationToken, continuationOptions As TaskContinuationOptions, scheduler As TaskScheduler) As Task

Parameters

continuationAction: Action<Task,Object>

An action to run when the Task completes. When run, the delegate will be passed the completed task and the caller-supplied state object as arguments.

state: Object

An object representing data to be used by the continuation action.

cancellationToken: CancellationToken

The CancellationToken that will be assigned to the new continuation task.

continuationOptions: 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: TaskScheduler

The TaskScheduler to associate with the continuation task and to use for its execution.

Returns

Task

A new continuation Task.

Exceptions

ArgumentNullException

The scheduler argument is null.

ArgumentOutOfRangeException

The continuationOptions argument specifies an invalid value for TaskContinuationOptions.

ObjectDisposedException

The provided CancellationToken has already been disposed.

Remarks

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.

Applies to

ContinueWith(Action<Task>, CancellationToken, TaskContinuationOptions, TaskScheduler)

Source:: Task.cs

Source:: Task.cs

Source:: Task.cs

Creates a continuation that executes when the target task competes according to the specified TaskContinuationOptions. The continuation receives a cancellation token and uses a specified scheduler.

public:
 System::Threading::Tasks::Task ^ ContinueWith(Action<System::Threading::Tasks::Task ^> ^ continuationAction, System::Threading::CancellationToken cancellationToken, System::Threading::Tasks::TaskContinuationOptions continuationOptions, System::Threading::Tasks::TaskScheduler ^ scheduler);

public System.Threading.Tasks.Task ContinueWith (Action<System.Threading.Tasks.Task> continuationAction, System.Threading.CancellationToken cancellationToken, System.Threading.Tasks.TaskContinuationOptions continuationOptions, System.Threading.Tasks.TaskScheduler scheduler);

member this.ContinueWith : Action<System.Threading.Tasks.Task> * System.Threading.CancellationToken * System.Threading.Tasks.TaskContinuationOptions * System.Threading.Tasks.TaskScheduler -> System.Threading.Tasks.Task

Public Function ContinueWith (continuationAction As Action(Of Task), cancellationToken As CancellationToken, continuationOptions As TaskContinuationOptions, scheduler As TaskScheduler) As Task

Parameters

continuationAction: 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: CancellationToken

The CancellationToken that will be assigned to the new continuation task.

continuationOptions: 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: TaskScheduler

The TaskScheduler to associate with the continuation task and to use for its execution.

Returns

Task

A new continuation Task.

Exceptions

ObjectDisposedException

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.

Examples

The following is an example of using ContinueWith to run work both in the background and on the user interface threads.

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);
}

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

Remarks

Applies to

ContinueWith(Action<Task,Object>, Object, TaskScheduler)

Source:: Task.cs

Source:: Task.cs

Source:: Task.cs

Creates a continuation that receives caller-supplied state information and executes asynchronously when the target Task completes. The continuation uses a specified scheduler.

public:
 System::Threading::Tasks::Task ^ ContinueWith(Action<System::Threading::Tasks::Task ^, System::Object ^> ^ continuationAction, System::Object ^ state, System::Threading::Tasks::TaskScheduler ^ scheduler);

public System.Threading.Tasks.Task ContinueWith (Action<System.Threading.Tasks.Task,object> continuationAction, object state, System.Threading.Tasks.TaskScheduler scheduler);

public System.Threading.Tasks.Task ContinueWith (Action<System.Threading.Tasks.Task,object?> continuationAction, object? state, System.Threading.Tasks.TaskScheduler scheduler);

member this.ContinueWith : Action<System.Threading.Tasks.Task, obj> * obj * System.Threading.Tasks.TaskScheduler -> System.Threading.Tasks.Task

Public Function ContinueWith (continuationAction As Action(Of Task, Object), state As Object, scheduler As TaskScheduler) As Task

Parameters

continuationAction: Action<Task,Object>

An action to run when the Task completes. When run, the delegate will be passed the completed task and the caller-supplied state object as arguments.

state: Object

An object representing data to be used by the continuation action.

scheduler: TaskScheduler

The TaskScheduler to associate with the continuation task and to use for its execution.

Returns

Task

A new continuation Task.

Exceptions

ArgumentNullException

The scheduler argument is null.

Remarks

The returned Task will not be scheduled for execution until the current task has completed, whether it completes due to running to completion successfully, faulting due to an unhandled exception, or exiting out early due to being canceled.

Applies to

ContinueWith(Action<Task,Object>, Object, TaskContinuationOptions)

Source:: Task.cs

Source:: Task.cs

Source:: Task.cs

Creates a continuation that receives caller-supplied state information and executes when the target Task completes. The continuation executes based on a set of specified conditions.

public:
 System::Threading::Tasks::Task ^ ContinueWith(Action<System::Threading::Tasks::Task ^, System::Object ^> ^ continuationAction, System::Object ^ state, System::Threading::Tasks::TaskContinuationOptions continuationOptions);

public System.Threading.Tasks.Task ContinueWith (Action<System.Threading.Tasks.Task,object> continuationAction, object state, System.Threading.Tasks.TaskContinuationOptions continuationOptions);

public System.Threading.Tasks.Task ContinueWith (Action<System.Threading.Tasks.Task,object?> continuationAction, object? state, System.Threading.Tasks.TaskContinuationOptions continuationOptions);

member this.ContinueWith : Action<System.Threading.Tasks.Task, obj> * obj * System.Threading.Tasks.TaskContinuationOptions -> System.Threading.Tasks.Task

Public Function ContinueWith (continuationAction As Action(Of Task, Object), state As Object, continuationOptions As TaskContinuationOptions) As Task

Parameters

continuationAction: Action<Task,Object>

An action to run when the Task completes. When run, the delegate will be passed the completed task and the caller-supplied state object as arguments.

state: Object

An object representing data to be used by the continuation action.

continuationOptions: 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.

Returns

Task

A new continuation Task.

Exceptions

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.

Applies to

ContinueWith(Action<Task,Object>, Object, CancellationToken)

Source:: Task.cs

Source:: Task.cs

Source:: Task.cs

Creates a continuation that receives caller-supplied state information and a cancellation token and that executes asynchronously when the target Task completes.

public:
 System::Threading::Tasks::Task ^ ContinueWith(Action<System::Threading::Tasks::Task ^, System::Object ^> ^ continuationAction, System::Object ^ state, System::Threading::CancellationToken cancellationToken);

public System.Threading.Tasks.Task ContinueWith (Action<System.Threading.Tasks.Task,object> continuationAction, object state, System.Threading.CancellationToken cancellationToken);

public System.Threading.Tasks.Task ContinueWith (Action<System.Threading.Tasks.Task,object?> continuationAction, object? state, System.Threading.CancellationToken cancellationToken);

member this.ContinueWith : Action<System.Threading.Tasks.Task, obj> * obj * System.Threading.CancellationToken -> System.Threading.Tasks.Task

Public Function ContinueWith (continuationAction As Action(Of Task, Object), state As Object, cancellationToken As CancellationToken) As Task

Parameters

continuationAction: Action<Task,Object>

An action to run when the Task completes. When run, the delegate will be passed the completed task and the caller-supplied state object as arguments.

state: Object

An object representing data to be used by the continuation action.

cancellationToken: CancellationToken

The CancellationToken that will be assigned to the new continuation task.

Returns

Task

A new continuation Task.

Exceptions

ArgumentNullException

The continuationAction argument is null.

ObjectDisposedException

The provided CancellationToken has already been disposed.

Remarks

Applies to

ContinueWith(Action<Task>)

Source:: Task.cs

Source:: Task.cs

Source:: Task.cs

Creates a continuation that executes asynchronously when the target Task completes.

public:
 System::Threading::Tasks::Task ^ ContinueWith(Action<System::Threading::Tasks::Task ^> ^ continuationAction);

public System.Threading.Tasks.Task ContinueWith (Action<System.Threading.Tasks.Task> continuationAction);

member this.ContinueWith : Action<System.Threading.Tasks.Task> -> System.Threading.Tasks.Task

Public Function ContinueWith (continuationAction As Action(Of Task)) As Task

Parameters

continuationAction: Action<Task>

An action to run when the Task completes. When run, the delegate will be passed the completed task as an argument.

Returns

Task

A new continuation Task.

Exceptions

ArgumentNullException

The continuationAction argument is null.

Examples

The following example defines a task that populates an array with 100 random date and time values. It uses the ContinueWith(Action<Task>) method to select the earliest and the latest date values once the array is fully populated.

using System;
using System.Threading.Tasks;

public class Example
{
   public static void Main()
   {
      var firstTask = Task.Factory.StartNew( () => {
                               Random rnd = new Random();
                               DateTime[] dates = new DateTime[100];
                               Byte[] buffer = new Byte[8];
                               int ctr = dates.GetLowerBound(0);
                               while (ctr <= dates.GetUpperBound(0)) {
                                  rnd.NextBytes(buffer);
                                  long ticks = BitConverter.ToInt64(buffer, 0);
                                  if (ticks <= DateTime.MinValue.Ticks | ticks >= DateTime.MaxValue.Ticks)
                                     continue;

                                  dates[ctr] = new DateTime(ticks);
                                  ctr++;
                               }
                               return dates;
                            } ); 
                         
      Task continuationTask = firstTask.ContinueWith( (antecedent) => {
                             DateTime[] dates = antecedent.Result;
                             DateTime earliest = dates[0];
                             DateTime latest = earliest;
                             
                             for (int ctr = dates.GetLowerBound(0) + 1; ctr <= dates.GetUpperBound(0); ctr++) {
                                if (dates[ctr] < earliest) earliest = dates[ctr];
                                if (dates[ctr] > latest) latest = dates[ctr];
                             }
                             Console.WriteLine("Earliest date: {0}", earliest);
                             Console.WriteLine("Latest date: {0}", latest);
                          } );                      
      // Since a console application otherwise terminates, wait for the continuation to complete.
     continuationTask.Wait();
   }
}
// The example displays output like the following:
//       Earliest date: 2/11/0110 12:03:41 PM
//       Latest date: 7/29/9989 2:14:49 PM

open System
open System.Threading.Tasks

let firstTask =
    Task.Factory.StartNew(fun () ->
        let rnd = Random()
        let dates = Array.zeroCreate 100
        let buffer = Array.zeroCreate 8
        let mutable i = dates.GetLowerBound 0

        while i <= dates.GetUpperBound 0 do
            rnd.NextBytes buffer
            let ticks = BitConverter.ToInt64(buffer, 0)

            if ticks > DateTime.MinValue.Ticks && ticks < DateTime.MaxValue.Ticks then
                dates[i] <- DateTime ticks
                i <- i + 1

        dates)

let continuationTask =
    firstTask.ContinueWith(
        Action<Task<DateTime[]>>(fun antecedent ->
            let dates: DateTime[] = antecedent.Result
            let mutable earliest = dates[0]
            let mutable latest = earliest

            for i = dates.GetLowerBound 0 + 1 to dates.GetUpperBound 0 do
                if dates.[i] < earliest then
                    earliest <- dates.[i]

                if dates.[i] > latest then
                    latest <- dates.[i]

            printfn $"Earliest date: {earliest}"
            printfn $"Latest date: {latest}")
    )
// Since a console application otherwise terminates, wait for the continuation to complete.
continuationTask.Wait()


// The example displays output like the following:
//       Earliest date: 2/11/0110 12:03:41 PM
//       Latest date: 7/29/9989 2:14:49 PM

Imports System.Threading.Tasks

Module Example
   Public Sub Main()
      Dim firstTask = Task.Factory.StartNew( Function()
                               Dim rnd As New Random()
                               Dim dates(99) As Date
                               Dim buffer(7) As Byte
                               Dim ctr As Integer = dates.GetLowerBound(0)
                               Do While ctr <= dates.GetUpperBound(0)
                                  rnd.NextBytes(buffer)
                                  Dim ticks As Long = BitConverter.ToInt64(buffer, 0)
                                  If ticks <= DateTime.MinValue.Ticks Or ticks >= DateTime.MaxValue.Ticks Then Continue Do

                                  dates(ctr) = New Date(ticks)
                                  ctr += 1
                               Loop
                               Return dates
                            End Function )
                         
      Dim continuationTask As Task = firstTask.ContinueWith( Sub(antecedent)
                             Dim dates() As Date = antecedent.Result
                             Dim earliest As Date = dates(0)
                             Dim latest As Date = earliest
                             
                             For ctr As Integer = dates.GetLowerBound(0) + 1 To dates.GetUpperBound(0)
                                If dates(ctr) < earliest Then earliest = dates(ctr)
                                If dates(ctr) > latest Then latest = dates(ctr)
                             Next
                             Console.WriteLine("Earliest date: {0}", earliest)
                             Console.WriteLine("Latest date: {0}", latest)
                          End Sub)                      
      ' Since a console application otherwise terminates, wait for the continuation to complete.
      continuationTask.Wait()
   End Sub
End Module
' The example displays output like the following:
'       Earliest date: 2/11/0110 12:03:41 PM
'       Latest date: 7/29/9989 2:14:49 PM

Because a console application may terminate before the continuation task executes, the Wait() method is called to ensure that the continuation finishes executing before the example ends.

For an additional example, see Chaining Tasks by Using Continuation Tasks.

Remarks

Applies to

ContinueWith(Action<Task>, TaskContinuationOptions)

Source:: Task.cs

Source:: Task.cs

Source:: Task.cs

Creates a continuation that executes when the target task completes according to the specified TaskContinuationOptions.

public:
 System::Threading::Tasks::Task ^ ContinueWith(Action<System::Threading::Tasks::Task ^> ^ continuationAction, System::Threading::Tasks::TaskContinuationOptions continuationOptions);

public System.Threading.Tasks.Task ContinueWith (Action<System.Threading.Tasks.Task> continuationAction, System.Threading.Tasks.TaskContinuationOptions continuationOptions);

member this.ContinueWith : Action<System.Threading.Tasks.Task> * System.Threading.Tasks.TaskContinuationOptions -> System.Threading.Tasks.Task

Public Function ContinueWith (continuationAction As Action(Of Task), continuationOptions As TaskContinuationOptions) As Task

Parameters

continuationAction: 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: 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.

Returns

Task

A new continuation Task.

Exceptions

ArgumentNullException

The continuationAction argument is null.

ArgumentOutOfRangeException

The continuationOptions argument specifies an invalid value for TaskContinuationOptions.

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.)

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; } }
}

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

Remarks

Applies to

ContinueWith(Action<Task>, CancellationToken)

Source:: Task.cs

Source:: Task.cs

Source:: Task.cs

Creates a continuation that receives a cancellation token and executes asynchronously when the target Task completes.

public:
 System::Threading::Tasks::Task ^ ContinueWith(Action<System::Threading::Tasks::Task ^> ^ continuationAction, System::Threading::CancellationToken cancellationToken);

public System.Threading.Tasks.Task ContinueWith (Action<System.Threading.Tasks.Task> continuationAction, System.Threading.CancellationToken cancellationToken);

member this.ContinueWith : Action<System.Threading.Tasks.Task> * System.Threading.CancellationToken -> System.Threading.Tasks.Task

Public Function ContinueWith (continuationAction As Action(Of Task), cancellationToken As CancellationToken) As Task

Parameters

continuationAction: Action<Task>

An action to run when the Task completes. When run, the delegate will be passed the completed task as an argument.

cancellationToken: CancellationToken

The CancellationToken that will be assigned to the new continuation task.

Returns

Task

A new continuation Task.

Exceptions

ObjectDisposedException

The CancellationTokenSource that created the token has already been disposed.

ArgumentNullException

The continuationAction argument is null.

Remarks

Applies to

ContinueWith(Action<Task,Object>, Object)

Source:: Task.cs

Source:: Task.cs

Source:: Task.cs

Creates a continuation that receives caller-supplied state information and executes when the target Task completes.

public:
 System::Threading::Tasks::Task ^ ContinueWith(Action<System::Threading::Tasks::Task ^, System::Object ^> ^ continuationAction, System::Object ^ state);

public System.Threading.Tasks.Task ContinueWith (Action<System.Threading.Tasks.Task,object> continuationAction, object state);

public System.Threading.Tasks.Task ContinueWith (Action<System.Threading.Tasks.Task,object?> continuationAction, object? state);

member this.ContinueWith : Action<System.Threading.Tasks.Task, obj> * obj -> System.Threading.Tasks.Task

Public Function ContinueWith (continuationAction As Action(Of Task, Object), state As Object) As Task

Parameters

continuationAction: Action<Task,Object>

An action to run when the task completes. When run, the delegate is passed the completed task and a caller-supplied state object as arguments.

state: Object

An object representing data to be used by the continuation action.

Returns

Task

A new continuation task.

Exceptions

ArgumentNullException

The continuationAction argument is null.

Remarks

Applies to

ContinueWith(Action<Task>, TaskScheduler)

Source:: Task.cs

Source:: Task.cs

Source:: Task.cs

Creates a continuation that executes asynchronously when the target Task completes. The continuation uses a specified scheduler.

public:
 System::Threading::Tasks::Task ^ ContinueWith(Action<System::Threading::Tasks::Task ^> ^ continuationAction, System::Threading::Tasks::TaskScheduler ^ scheduler);

public System.Threading.Tasks.Task ContinueWith (Action<System.Threading.Tasks.Task> continuationAction, System.Threading.Tasks.TaskScheduler scheduler);

member this.ContinueWith : Action<System.Threading.Tasks.Task> * System.Threading.Tasks.TaskScheduler -> System.Threading.Tasks.Task

Public Function ContinueWith (continuationAction As Action(Of Task), scheduler As TaskScheduler) As Task

Parameters

continuationAction: Action<Task>

An action to run when the Task completes. When run, the delegate will be passed the completed task as an argument.

scheduler: TaskScheduler

The TaskScheduler to associate with the continuation task and to use for its execution.

Returns

Task

A new continuation Task.

Exceptions

ObjectDisposedException

The Task has been disposed.

ArgumentNullException

The continuationAction argument is null.

-or-

The scheduler argument is null.

Remarks

Applies to

ContinueWith<TResult>(Func<Task,Object,TResult>, Object, TaskScheduler)

Source:: Task.cs

Source:: Task.cs

Source:: Task.cs

Creates a continuation that executes asynchronously when the target Task completes. The continuation receives caller-supplied state information and uses a specified scheduler.

public:
generic <typename TResult>
 System::Threading::Tasks::Task<TResult> ^ ContinueWith(Func<System::Threading::Tasks::Task ^, System::Object ^, TResult> ^ continuationFunction, System::Object ^ state, System::Threading::Tasks::TaskScheduler ^ scheduler);

public System.Threading.Tasks.Task<TResult> ContinueWith<TResult> (Func<System.Threading.Tasks.Task,object,TResult> continuationFunction, object state, System.Threading.Tasks.TaskScheduler scheduler);

public System.Threading.Tasks.Task<TResult> ContinueWith<TResult> (Func<System.Threading.Tasks.Task,object?,TResult> continuationFunction, object? state, System.Threading.Tasks.TaskScheduler scheduler);

member this.ContinueWith : Func<System.Threading.Tasks.Task, obj, 'Result> * obj * System.Threading.Tasks.TaskScheduler -> System.Threading.Tasks.Task<'Result>

Public Function ContinueWith(Of TResult) (continuationFunction As Func(Of Task, Object, TResult), state As Object, scheduler As TaskScheduler) As Task(Of TResult)

Type Parameters

TResult

The type of the result produced by the continuation.

Parameters

continuationFunction: Func<Task,Object,TResult>

A function to run when the Task completes. When run, the delegate will be passed the completed task and the caller-supplied state object as arguments.

state: Object

An object representing data to be used by the continuation function.

scheduler: TaskScheduler

The TaskScheduler to associate with the continuation task and to use for its execution.

Returns

Task<TResult>

A new continuation Task<TResult>.

Exceptions

ArgumentNullException

The scheduler argument is null.

Remarks

The returned Task<TResult> will not be scheduled for execution until the current task has completed, whether it completes due to running to completion successfully, faulting due to an unhandled exception, or exiting out early due to being canceled.

Applies to

ContinueWith<TResult>(Func<Task,Object,TResult>, Object, CancellationToken, TaskContinuationOptions, TaskScheduler)

Source:: Task.cs

Source:: Task.cs

Source:: Task.cs

Creates a continuation that executes based on the specified task continuation options when the target Task completes and returns a value. The continuation receives caller-supplied state information and a cancellation token and uses the specified scheduler.

public:
generic <typename TResult>
 System::Threading::Tasks::Task<TResult> ^ ContinueWith(Func<System::Threading::Tasks::Task ^, System::Object ^, TResult> ^ continuationFunction, System::Object ^ state, System::Threading::CancellationToken cancellationToken, System::Threading::Tasks::TaskContinuationOptions continuationOptions, System::Threading::Tasks::TaskScheduler ^ scheduler);

public System.Threading.Tasks.Task<TResult> ContinueWith<TResult> (Func<System.Threading.Tasks.Task,object,TResult> continuationFunction, object state, System.Threading.CancellationToken cancellationToken, System.Threading.Tasks.TaskContinuationOptions continuationOptions, System.Threading.Tasks.TaskScheduler scheduler);

public System.Threading.Tasks.Task<TResult> ContinueWith<TResult> (Func<System.Threading.Tasks.Task,object?,TResult> continuationFunction, object? state, System.Threading.CancellationToken cancellationToken, System.Threading.Tasks.TaskContinuationOptions continuationOptions, System.Threading.Tasks.TaskScheduler scheduler);

member this.ContinueWith : Func<System.Threading.Tasks.Task, obj, 'Result> * obj * System.Threading.CancellationToken * System.Threading.Tasks.TaskContinuationOptions * System.Threading.Tasks.TaskScheduler -> System.Threading.Tasks.Task<'Result>

Public Function ContinueWith(Of TResult) (continuationFunction As Func(Of Task, Object, TResult), state As Object, cancellationToken As CancellationToken, continuationOptions As TaskContinuationOptions, scheduler As TaskScheduler) As Task(Of TResult)

Type Parameters

TResult

The type of the result produced by the continuation.

Parameters

continuationFunction: Func<Task,Object,TResult>

A function to run when the Task completes. When run, the delegate will be passed the completed task and the caller-supplied state object as arguments.

state: Object

An object representing data to be used by the continuation function.

cancellationToken: CancellationToken

The CancellationToken that will be assigned to the new continuation task.

continuationOptions: 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: TaskScheduler

The TaskScheduler to associate with the continuation task and to use for its execution.

Returns

Task<TResult>

A new continuation Task<TResult>.

Exceptions

ArgumentNullException

The scheduler argument is null.

ArgumentOutOfRangeException

The continuationOptions argument specifies an invalid value for TaskContinuationOptions.

ObjectDisposedException

The provided CancellationToken has already been disposed.

Remarks

The returned Task<TResult> 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.

Applies to

ContinueWith<TResult>(Func<Task,TResult>, CancellationToken, TaskContinuationOptions, TaskScheduler)

Source:: Task.cs

Source:: Task.cs

Source:: Task.cs

Creates a continuation that executes according to the specified continuation options and returns a value. The continuation is passed a cancellation token and uses a specified scheduler.

public:
generic <typename TResult>
 System::Threading::Tasks::Task<TResult> ^ ContinueWith(Func<System::Threading::Tasks::Task ^, TResult> ^ continuationFunction, System::Threading::CancellationToken cancellationToken, System::Threading::Tasks::TaskContinuationOptions continuationOptions, System::Threading::Tasks::TaskScheduler ^ scheduler);

public System.Threading.Tasks.Task<TResult> ContinueWith<TResult> (Func<System.Threading.Tasks.Task,TResult> continuationFunction, System.Threading.CancellationToken cancellationToken, System.Threading.Tasks.TaskContinuationOptions continuationOptions, System.Threading.Tasks.TaskScheduler scheduler);

member this.ContinueWith : Func<System.Threading.Tasks.Task, 'Result> * System.Threading.CancellationToken * System.Threading.Tasks.TaskContinuationOptions * System.Threading.Tasks.TaskScheduler -> System.Threading.Tasks.Task<'Result>

Public Function ContinueWith(Of TResult) (continuationFunction As Func(Of Task, TResult), cancellationToken As CancellationToken, continuationOptions As TaskContinuationOptions, scheduler As TaskScheduler) As Task(Of TResult)

Type Parameters

TResult

The type of the result produced by the continuation.

Parameters

continuationFunction: Func<Task,TResult>

A function to run according to the specified continuationOptions. When run, the delegate will be passed the completed task as an argument.

cancellationToken: CancellationToken

The CancellationToken that will be assigned to the new continuation task.

continuationOptions: 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: TaskScheduler

The TaskScheduler to associate with the continuation task and to use for its execution.

Returns

Task<TResult>

A new continuation Task<TResult>.

Exceptions

ObjectDisposedException

The Task has been disposed.

-or-

The CancellationTokenSource that created the token has already been disposed.

ArgumentNullException

The continuationFunction argument is null.

-or-

The scheduler argument is null.

ArgumentOutOfRangeException

The continuationOptions argument specifies an invalid value for TaskContinuationOptions.

Examples

The following example shows how to use the ContinueWith method with continuation options:

using System;
using System.Threading;
using System.Threading.Tasks;

class ContinuationOptionsDemo
{
    // Demonstrated features:
    //      TaskContinuationOptions
    //		Task.ContinueWith()
    // 		Task.Factory
    //		Task.Wait()
    // Expected results:
    // 		This sample demonstrates branched continuation sequences - Task+Commit or Task+Rollback.
    //      Notice that no if statements are used.
    //		The first sequence is successful - tran1 and commitTran1 are executed. rollbackTran1 is canceled.
    //		The second sequence is unsuccessful - tran2 and rollbackTran2 are executed. tran2 is faulted, and commitTran2 is canceled.
    // Documentation:
    //		http://msdn.microsoft.com/library/system.threading.tasks.taskcontinuationoptions(VS.100).aspx
    static void Main()
    {
        Action success = () => Console.WriteLine("Task={0}, Thread={1}: Begin successful transaction",
                                                Task.CurrentId, Thread.CurrentThread.ManagedThreadId);
        Action failure = () =>
        {
            Console.WriteLine("Task={0}, Thread={1}: Begin transaction and encounter an error",
                                Task.CurrentId, Thread.CurrentThread.ManagedThreadId);
            throw new InvalidOperationException("SIMULATED EXCEPTION");
        };

        Action<Task> commit = (antecendent) => Console.WriteLine("Task={0}, Thread={1}: Commit transaction",
                                                                Task.CurrentId, Thread.CurrentThread.ManagedThreadId);
        Action<Task> rollback = (antecendent) =>
        {
            // "Observe" your antecedent's exception so as to avoid an exception
            // being thrown on the finalizer thread
            var unused = antecendent.Exception;

            Console.WriteLine("Task={0}, Thread={1}: Rollback transaction",
                  Task.CurrentId, Thread.CurrentThread.ManagedThreadId);
        };

        // Successful transaction - Begin + Commit
        Console.WriteLine("Demonstrating a successful transaction");

        // Initial task
        // Treated as "fire-and-forget" -- any exceptions will be cleaned up in rollback continuation
        Task tran1 = Task.Factory.StartNew(success);

        // The following task gets scheduled only if tran1 completes successfully
        var commitTran1 = tran1.ContinueWith(commit, TaskContinuationOptions.OnlyOnRanToCompletion);

        // The following task gets scheduled only if tran1 DOES NOT complete successfully
        var rollbackTran1 = tran1.ContinueWith(rollback, TaskContinuationOptions.NotOnRanToCompletion);

        // For demo purposes, wait for the sample to complete
        commitTran1.Wait();

        // -----------------------------------------------------------------------------------

        // Failed transaction - Begin + exception + Rollback
        Console.WriteLine("\nDemonstrating a failed transaction");

        // Initial task
        // Treated as "fire-and-forget" -- any exceptions will be cleaned up in rollback continuation
        Task tran2 = Task.Factory.StartNew(failure);

        // The following task gets scheduled only if tran2 completes successfully
        var commitTran2 = tran2.ContinueWith(commit, TaskContinuationOptions.OnlyOnRanToCompletion);

        // The following task gets scheduled only if tran2 DOES NOT complete successfully
        var rollbackTran2 = tran2.ContinueWith(rollback, TaskContinuationOptions.NotOnRanToCompletion);

        // For demo purposes, wait for the sample to complete
        rollbackTran2.Wait();
    }
}

open System
open System.Threading
open System.Threading.Tasks

// Demonstrated features:
//      TaskContinuationOptions
//		Task.ContinueWith()
// 		Task.Factory
//		Task.Wait()
// Expected results:
// 		This sample demonstrates branched continuation sequences - Task+Commit or Task+Rollback.
//      Notice that no if statements are used.
//		The first sequence is successful - tran1 and commitTran1 are executed. rollbackTran1 is canceled.
//		The second sequence is unsuccessful - tran2 and rollbackTran2 are executed. tran2 is faulted, and commitTran2 is canceled.
// Documentation:
//		http://msdn.microsoft.com/library/system.threading.tasks.taskcontinuationoptions(VS.100).aspx
let success =
    fun () ->
        printfn $"Task={Task.CurrentId}, Thread={Thread.CurrentThread.ManagedThreadId}: Begin successful transaction"

let failure =
    fun () ->

        printfn
            $"Task={Task.CurrentId}, Thread={Thread.CurrentThread.ManagedThreadId}: Begin transaction and encounter an error"

        raise (InvalidOperationException "SIMULATED EXCEPTION")

let commit =
    fun antecendent ->
        printfn $"Task={Task.CurrentId}, Thread={Thread.CurrentThread.ManagedThreadId}: Commit transaction"

let rollback =
    fun (antecendent: Task) ->

        // "Observe" your antecedent's exception so as to avoid an exception
        // being thrown on the finalizer thread
        let unused = antecendent.Exception

        printfn $"Task={Task.CurrentId}, Thread={Thread.CurrentThread.ManagedThreadId}: Rollback transaction"

// Successful transaction - Begin + Commit
printfn "Demonstrating a successful transaction"

// Initial task
// Treated as "fire-and-forget" -- any exceptions will be cleaned up in rollback continuation
let tran1 = Task.Factory.StartNew success

// The following task gets scheduled only if tran1 completes successfully
let commitTran1 =
    tran1.ContinueWith(commit, TaskContinuationOptions.OnlyOnRanToCompletion)

// The following task gets scheduled only if tran1 DOES NOT complete successfully
let rollbackTran1 =
    tran1.ContinueWith(rollback, TaskContinuationOptions.NotOnRanToCompletion)

// For demo purposes, wait for the sample to complete
commitTran1.Wait()

// -----------------------------------------------------------------------------------

// Failed transaction - Begin + exception + Rollback
printfn "\nDemonstrating a failed transaction"

// Initial task
// Treated as "fire-and-forget" -- any exceptions will be cleaned up in rollback continuation
let tran2: Task = Task.Factory.StartNew failure

// The following task gets scheduled only if tran2 completes successfully
let commitTran2 =
    tran2.ContinueWith(Action<Task> commit, TaskContinuationOptions.OnlyOnRanToCompletion)

// The following task gets scheduled only if tran2 DOES NOT complete successfully
let rollbackTran2 =
    tran2.ContinueWith(Action<Task> rollback, TaskContinuationOptions.NotOnRanToCompletion)

// For demo purposes, wait for the sample to complete
rollbackTran2.Wait()

Imports System.Threading
Imports System.Threading.Tasks

Module ContuationOptionsDemo
    ' Demonstrated features:
    '   TaskContinuationOptions
    '   Task.ContinueWith()
    '   Task.Factory
    '   Task.Wait()
    ' Expected results:
    '   This sample demonstrates branched continuation sequences - Task+Commit or Task+Rollback.
    '   Notice that no if statements are used.
    '   The first sequence is successful - tran1 and commitTran1 are executed. rollbackTran1 is canceled.
    '   The second sequence is unsuccessful - tran2 and rollbackTran2 are executed. tran2 is faulted, and commitTran2 is canceled.
    ' Documentation:
    '   http://msdn.microsoft.com/library/system.threading.tasks.taskcontinuationoptions(VS.100).aspx
    Private Sub Main()
        Dim success As Action = Sub()
                                    Console.WriteLine("Task={0}, Thread={1}: Begin successful transaction", Task.CurrentId, Thread.CurrentThread.ManagedThreadId)
                                End Sub

        Dim failure As Action = Sub()
                                    Console.WriteLine("Task={0}, Thread={1}: Begin transaction and encounter an error", Task.CurrentId, Thread.CurrentThread.ManagedThreadId)
                                    Throw New InvalidOperationException("SIMULATED EXCEPTION")
                                End Sub

        Dim commit As Action(Of Task) = Sub(antecendent)
                                            Console.WriteLine("Task={0}, Thread={1}: Commit transaction", Task.CurrentId, Thread.CurrentThread.ManagedThreadId)
                                        End Sub

        Dim rollback As Action(Of Task) = Sub(antecendent)
                                              ' "Observe" your antecedent's exception so as to avoid an exception
                                              ' being thrown on the finalizer thread
                                              Dim unused = antecendent.Exception

                                              Console.WriteLine("Task={0}, Thread={1}: Rollback transaction", Task.CurrentId, Thread.CurrentThread.ManagedThreadId)
                                          End Sub

        ' Successful transaction - Begin + Commit
        Console.WriteLine("Demonstrating a successful transaction")

        ' Initial task
        ' Treated as "fire-and-forget" -- any exceptions will be cleaned up in rollback continuation
        Dim tran1 As Task = Task.Factory.StartNew(success)

        ' The following task gets scheduled only if tran1 completes successfully
        Dim commitTran1 = tran1.ContinueWith(commit, TaskContinuationOptions.OnlyOnRanToCompletion)

        ' The following task gets scheduled only if tran1 DOES NOT complete successfully
        Dim rollbackTran1 = tran1.ContinueWith(rollback, TaskContinuationOptions.NotOnRanToCompletion)

        ' For demo purposes, wait for the sample to complete
        commitTran1.Wait()

        ' -----------------------------------------------------------------------------------


        ' Failed transaction - Begin + exception + Rollback 
        Console.WriteLine(vbLf & "Demonstrating a failed transaction")

        ' Initial task
        ' Treated as "fire-and-forget" -- any exceptions will be cleaned up in rollback continuation
        Dim tran2 As Task = Task.Factory.StartNew(failure)

        ' The following task gets scheduled only if tran2 completes successfully
        Dim commitTran2 = tran2.ContinueWith(commit, TaskContinuationOptions.OnlyOnRanToCompletion)

        ' The following task gets scheduled only if tran2 DOES NOT complete successfully
        Dim rollbackTran2 = tran2.ContinueWith(rollback, TaskContinuationOptions.NotOnRanToCompletion)

        ' For demo purposes, wait for the sample to complete
        rollbackTran2.Wait()
    End Sub
End Module

Remarks

Applies to

ContinueWith<TResult>(Func<Task,Object,TResult>, Object, CancellationToken)

Source:: Task.cs

Source:: Task.cs

Source:: Task.cs

Creates a continuation that executes asynchronously when the target Task completes and returns a value. The continuation receives caller-supplied state information and a cancellation token.

public:
generic <typename TResult>
 System::Threading::Tasks::Task<TResult> ^ ContinueWith(Func<System::Threading::Tasks::Task ^, System::Object ^, TResult> ^ continuationFunction, System::Object ^ state, System::Threading::CancellationToken cancellationToken);

public System.Threading.Tasks.Task<TResult> ContinueWith<TResult> (Func<System.Threading.Tasks.Task,object,TResult> continuationFunction, object state, System.Threading.CancellationToken cancellationToken);

public System.Threading.Tasks.Task<TResult> ContinueWith<TResult> (Func<System.Threading.Tasks.Task,object?,TResult> continuationFunction, object? state, System.Threading.CancellationToken cancellationToken);

member this.ContinueWith : Func<System.Threading.Tasks.Task, obj, 'Result> * obj * System.Threading.CancellationToken -> System.Threading.Tasks.Task<'Result>

Public Function ContinueWith(Of TResult) (continuationFunction As Func(Of Task, Object, TResult), state As Object, cancellationToken As CancellationToken) As Task(Of TResult)

Type Parameters

TResult

The type of the result produced by the continuation.

Parameters

continuationFunction: Func<Task,Object,TResult>

A function to run when the Task completes. When run, the delegate will be passed the completed task and the caller-supplied state object as arguments.

state: Object

An object representing data to be used by the continuation function.

cancellationToken: CancellationToken

The CancellationToken that will be assigned to the new continuation task.

Returns

Task<TResult>

A new continuation Task<TResult>.

Exceptions

ArgumentNullException

The continuationFunction argument is null.

ObjectDisposedException

The provided CancellationToken has already been disposed.

Remarks

Applies to

ContinueWith<TResult>(Func<Task,Object,TResult>, Object, TaskContinuationOptions)

Source:: Task.cs

Source:: Task.cs

Source:: Task.cs

Creates a continuation that executes based on the specified task continuation options when the target Task completes. The continuation receives caller-supplied state information.

public:
generic <typename TResult>
 System::Threading::Tasks::Task<TResult> ^ ContinueWith(Func<System::Threading::Tasks::Task ^, System::Object ^, TResult> ^ continuationFunction, System::Object ^ state, System::Threading::Tasks::TaskContinuationOptions continuationOptions);

public System.Threading.Tasks.Task<TResult> ContinueWith<TResult> (Func<System.Threading.Tasks.Task,object,TResult> continuationFunction, object state, System.Threading.Tasks.TaskContinuationOptions continuationOptions);

public System.Threading.Tasks.Task<TResult> ContinueWith<TResult> (Func<System.Threading.Tasks.Task,object?,TResult> continuationFunction, object? state, System.Threading.Tasks.TaskContinuationOptions continuationOptions);

member this.ContinueWith : Func<System.Threading.Tasks.Task, obj, 'Result> * obj * System.Threading.Tasks.TaskContinuationOptions -> System.Threading.Tasks.Task<'Result>

Public Function ContinueWith(Of TResult) (continuationFunction As Func(Of Task, Object, TResult), state As Object, continuationOptions As TaskContinuationOptions) As Task(Of TResult)

Type Parameters

TResult

The type of the result produced by the continuation.

Parameters

continuationFunction: Func<Task,Object,TResult>

A function to run when the Task completes. When run, the delegate will be passed the completed task and the caller-supplied state object as arguments.

state: Object

An object representing data to be used by the continuation function.

continuationOptions: 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.

Returns

Task<TResult>

A new continuation Task<TResult>.

Exceptions

ArgumentNullException

The continuationFunction argument is null.

ArgumentOutOfRangeException

The continuationOptions argument specifies an invalid value for TaskContinuationOptions.

Remarks

The returned Task<TResult> 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.

Applies to

ContinueWith<TResult>(Func<Task,TResult>, TaskContinuationOptions)

Source:: Task.cs

Source:: Task.cs

Source:: Task.cs

Creates a continuation that executes according to the specified continuation options and returns a value.

public:
generic <typename TResult>
 System::Threading::Tasks::Task<TResult> ^ ContinueWith(Func<System::Threading::Tasks::Task ^, TResult> ^ continuationFunction, System::Threading::Tasks::TaskContinuationOptions continuationOptions);

public System.Threading.Tasks.Task<TResult> ContinueWith<TResult> (Func<System.Threading.Tasks.Task,TResult> continuationFunction, System.Threading.Tasks.TaskContinuationOptions continuationOptions);

member this.ContinueWith : Func<System.Threading.Tasks.Task, 'Result> * System.Threading.Tasks.TaskContinuationOptions -> System.Threading.Tasks.Task<'Result>

Public Function ContinueWith(Of TResult) (continuationFunction As Func(Of Task, TResult), continuationOptions As TaskContinuationOptions) As Task(Of TResult)

Type Parameters

TResult

The type of the result produced by the continuation.

Parameters

continuationFunction: Func<Task,TResult>

A function to run according to the condition specified in continuationOptions. When run, the delegate will be passed the completed task as an argument.

continuationOptions: 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.

Returns

Task<TResult>

A new continuation Task<TResult>.

Exceptions

ObjectDisposedException

The Task has been disposed.

ArgumentNullException

The continuationFunction argument is null.

ArgumentOutOfRangeException

The continuationOptions argument specifies an invalid value for TaskContinuationOptions.

Remarks

Applies to

ContinueWith<TResult>(Func<Task,TResult>, TaskScheduler)

Source:: Task.cs

Source:: Task.cs

Source:: Task.cs

Creates a continuation that executes asynchronously when the target Task completes and returns a value. The continuation uses a specified scheduler.

public:
generic <typename TResult>
 System::Threading::Tasks::Task<TResult> ^ ContinueWith(Func<System::Threading::Tasks::Task ^, TResult> ^ continuationFunction, System::Threading::Tasks::TaskScheduler ^ scheduler);

public System.Threading.Tasks.Task<TResult> ContinueWith<TResult> (Func<System.Threading.Tasks.Task,TResult> continuationFunction, System.Threading.Tasks.TaskScheduler scheduler);

member this.ContinueWith : Func<System.Threading.Tasks.Task, 'Result> * System.Threading.Tasks.TaskScheduler -> System.Threading.Tasks.Task<'Result>

Public Function ContinueWith(Of TResult) (continuationFunction As Func(Of Task, TResult), scheduler As TaskScheduler) As Task(Of TResult)

Type Parameters

TResult

The type of the result produced by the continuation.

Parameters

continuationFunction: Func<Task,TResult>

A function to run when the Task completes. When run, the delegate will be passed the completed task as an argument.

scheduler: TaskScheduler

The TaskScheduler to associate with the continuation task and to use for its execution.

Returns

Task<TResult>

A new continuation Task<TResult>.

Exceptions

ObjectDisposedException

The Task has been disposed.

ArgumentNullException

The continuationFunction argument is null.

-or-

The scheduler argument is null.

Remarks

Applies to

ContinueWith<TResult>(Func<Task,TResult>, CancellationToken)

Source:: Task.cs

Source:: Task.cs

Source:: Task.cs

Creates a continuation that executes asynchronously when the target Task completes and returns a value. The continuation receives a cancellation token.

public:
generic <typename TResult>
 System::Threading::Tasks::Task<TResult> ^ ContinueWith(Func<System::Threading::Tasks::Task ^, TResult> ^ continuationFunction, System::Threading::CancellationToken cancellationToken);

public System.Threading.Tasks.Task<TResult> ContinueWith<TResult> (Func<System.Threading.Tasks.Task,TResult> continuationFunction, System.Threading.CancellationToken cancellationToken);

member this.ContinueWith : Func<System.Threading.Tasks.Task, 'Result> * System.Threading.CancellationToken -> System.Threading.Tasks.Task<'Result>

Public Function ContinueWith(Of TResult) (continuationFunction As Func(Of Task, TResult), cancellationToken As CancellationToken) As Task(Of TResult)

Type Parameters

TResult

The type of the result produced by the continuation.

Parameters

continuationFunction: Func<Task,TResult>

A function to run when the Task completes. When run, the delegate will be passed the completed task as an argument.

cancellationToken: CancellationToken

The CancellationToken that will be assigned to the new continuation task.

Returns

Task<TResult>

A new continuation Task<TResult>.

Exceptions

ObjectDisposedException

The Task has been disposed.

-or-

The CancellationTokenSource that created the token has already been disposed.

ArgumentNullException

The continuationFunction argument is null.

Remarks

Applies to

ContinueWith<TResult>(Func<Task,Object,TResult>, Object)

Source:: Task.cs

Source:: Task.cs

Source:: Task.cs

Creates a continuation that receives caller-supplied state information and executes asynchronously when the target Task completes and returns a value.

public:
generic <typename TResult>
 System::Threading::Tasks::Task<TResult> ^ ContinueWith(Func<System::Threading::Tasks::Task ^, System::Object ^, TResult> ^ continuationFunction, System::Object ^ state);

public System.Threading.Tasks.Task<TResult> ContinueWith<TResult> (Func<System.Threading.Tasks.Task,object,TResult> continuationFunction, object state);

public System.Threading.Tasks.Task<TResult> ContinueWith<TResult> (Func<System.Threading.Tasks.Task,object?,TResult> continuationFunction, object? state);

member this.ContinueWith : Func<System.Threading.Tasks.Task, obj, 'Result> * obj -> System.Threading.Tasks.Task<'Result>

Public Function ContinueWith(Of TResult) (continuationFunction As Func(Of Task, Object, TResult), state As Object) As Task(Of TResult)

Type Parameters

TResult

The type of the result produced by the continuation.

Parameters

continuationFunction: Func<Task,Object,TResult>

A function to run when the Task completes. When run, the delegate will be passed the completed task and the caller-supplied state object as arguments.

state: Object

An object representing data to be used by the continuation function.

Returns

Task<TResult>

A new continuation Task<TResult>.

Exceptions

ArgumentNullException

The continuationFunction argument is null.

Remarks

Applies to

ContinueWith<TResult>(Func<Task,TResult>)

Source:: Task.cs

Source:: Task.cs

Source:: Task.cs

Creates a continuation that executes asynchronously when the target Task<TResult> completes and returns a value.

public:
generic <typename TResult>
 System::Threading::Tasks::Task<TResult> ^ ContinueWith(Func<System::Threading::Tasks::Task ^, TResult> ^ continuationFunction);

public System.Threading.Tasks.Task<TResult> ContinueWith<TResult> (Func<System.Threading.Tasks.Task,TResult> continuationFunction);

member this.ContinueWith : Func<System.Threading.Tasks.Task, 'Result> -> System.Threading.Tasks.Task<'Result>

Public Function ContinueWith(Of TResult) (continuationFunction As Func(Of Task, TResult)) As Task(Of TResult)

Type Parameters

TResult

The type of the result produced by the continuation.

Parameters

continuationFunction: Func<Task,TResult>

A function to run when the Task<TResult> completes. When run, the delegate will be passed the completed task as an argument.

Returns

Task<TResult>

A new continuation task.

Exceptions

ObjectDisposedException

The Task has been disposed.

ArgumentNullException

The continuationFunction argument is null.

Examples

The following example shows how to use the ContinueWith method:

using System;
using System.Threading;
using System.Threading.Tasks;

class ContinuationSimpleDemo
{
    // Demonstrated features:
    // 		Task.Factory
    //		Task.ContinueWith()
    //		Task.Wait()
    // Expected results:
    // 		A sequence of three unrelated tasks is created and executed in this order - alpha, beta, gamma.
    //		A sequence of three related tasks is created - each task negates its argument and passes is to the next task: 5, -5, 5 is printed.
    //		A sequence of three unrelated tasks is created where tasks have different types.
    // Documentation:
    //		http://msdn.microsoft.com/library/system.threading.tasks.taskfactory_members(VS.100).aspx
    static void Main()
    {
        Action<string> action =
            (str) =>
                Console.WriteLine("Task={0}, str={1}, Thread={2}", Task.CurrentId, str, Thread.CurrentThread.ManagedThreadId);

        // Creating a sequence of action tasks (that return no result).
        Console.WriteLine("Creating a sequence of action tasks (that return no result)");
        Task.Factory.StartNew(() => action("alpha"))
            .ContinueWith(antecendent => action("beta"))        // Antecedent data is ignored
            .ContinueWith(antecendent => action("gamma"))
            .Wait();

        Func<int, int> negate =
            (n) =>
            {
                Console.WriteLine("Task={0}, n={1}, -n={2}, Thread={3}", Task.CurrentId, n, -n, Thread.CurrentThread.ManagedThreadId);
                return -n;
            };

        // Creating a sequence of function tasks where each continuation uses the result from its antecendent
        Console.WriteLine("\nCreating a sequence of function tasks where each continuation uses the result from its antecendent");
        Task<int>.Factory.StartNew(() => negate(5))
            .ContinueWith(antecendent => negate(antecendent.Result))		// Antecedent result feeds into continuation
            .ContinueWith(antecendent => negate(antecendent.Result))
            .Wait();

        // Creating a sequence of tasks where you can mix and match the types
        Console.WriteLine("\nCreating a sequence of tasks where you can mix and match the types");
        Task<int>.Factory.StartNew(() => negate(6))
            .ContinueWith(antecendent => action("x"))
            .ContinueWith(antecendent => negate(7))
            .Wait();
    }
}

open System
open System.Threading
open System.Threading.Tasks

// Demonstrated features:
// 		Task.Factory
//		Task.ContinueWith()
//		Task.Wait()
// Expected results:
// 		A sequence of three unrelated tasks is created and executed in this order - alpha, beta, gamma.
//		A sequence of three related tasks is created - each task negates its argument and passes is to the next task: 5, -5, 5 is printed.
//		A sequence of three unrelated tasks is created where tasks have different types.
// Documentation:
//		http://msdn.microsoft.com/library/system.threading.tasks.taskfactory_members(VS.100).aspx
let action =
    fun str -> printfn $"Task={Task.CurrentId}, str=%s{str}, Thread={Thread.CurrentThread.ManagedThreadId}"

// Creating a sequence of action tasks (that return no result).
printfn "Creating a sequence of action tasks (that return no result)"

Task
    .Factory
    .StartNew(fun () -> action "alpha")
    .ContinueWith(fun antecendent -> action "beta") // Antecedent data is ignored
    .ContinueWith(fun antecendent -> action "gamma")
    .Wait()

let negate =
    fun n ->
        printfn $"Task={Task.CurrentId}, n={n}, -n={2 - n}, Thread={Thread.CurrentThread.ManagedThreadId}"
        -n

// Creating a sequence of function tasks where each continuation uses the result from its antecendent
printfn "\nCreating a sequence of function tasks where each continuation uses the result from its antecendent"

Task<int>
    .Factory.StartNew(fun () -> negate 5)
    .ContinueWith(Func<Task<int>, int>(fun antecedent -> negate antecedent.Result)) // Antecedent result feeds into continuation
    .ContinueWith(Func<Task<int>, int>(fun antecedent -> negate antecedent.Result))
    .Wait()

// Creating a sequence of tasks where you can mix and match the types
printfn "\nCreating a sequence of tasks where you can mix and match the types"

Task<int>
    .Factory.StartNew(fun () -> negate 6)
    .ContinueWith(Action<Task>(fun antecendent -> action "x"))
    .ContinueWith(fun antecendent -> negate 7)
    .Wait()

Imports System.Threading
Imports System.Threading.Tasks

Module ContinuationDemo

    ' Demonstrated features:
    '   Task.Factory
    '   Task.ContinueWith()
    '   Task.Wait()
    ' Expected results:
    '   A sequence of three unrelated tasks is created and executed in this order - alpha, beta, gamma.
    '   A sequence of three related tasks is created - each task negates its argument and passes is to the next task: 5, -5, 5 is printed.
    '   A sequence of three unrelated tasks is created where tasks have different types.
    ' Documentation:
    '   http://msdn.microsoft.com/library/system.threading.tasks.taskfactory_members(VS.100).aspx
    Sub Main()
        Dim action As Action(Of String) = Sub(str) Console.WriteLine("Task={0}, str={1}, Thread={2}", Task.CurrentId, str, Thread.CurrentThread.ManagedThreadId)

        ' Creating a sequence of action tasks (that return no result).
        Console.WriteLine("Creating a sequence of action tasks (that return no result)")
        ' Continuations ignore antecedent data
        Task.Factory.StartNew(Sub() action("alpha")).ContinueWith(Sub(antecendent) action("beta")).ContinueWith(Sub(antecendent) action("gamma")).Wait()


        Dim negate As Func(Of Integer, Integer) = Function(n)
                                                      Console.WriteLine("Task={0}, n={1}, -n={2}, Thread={3}", Task.CurrentId, n, -n, Thread.CurrentThread.ManagedThreadId)
                                                      Return -n
                                                  End Function

        ' Creating a sequence of function tasks where each continuation uses the result from its antecendent
        Console.WriteLine(vbLf & "Creating a sequence of function tasks where each continuation uses the result from its antecendent")
        Task(Of Integer).Factory.StartNew(Function() negate(5)).ContinueWith(Function(antecendent) negate(antecendent.Result)).ContinueWith(Function(antecendent) negate(antecendent.Result)).Wait()


        ' Creating a sequence of tasks where you can mix and match the types
        Console.WriteLine(vbLf & "Creating a sequence of tasks where you can mix and match the types")
        Task(Of Integer).Factory.StartNew(Function() negate(6)).ContinueWith(Sub(antecendent) action("x")).ContinueWith(Function(antecendent) negate(7)).Wait()
    End Sub
End Module

Remarks

Applies to

Zdieľať cez

Task.ContinueWith Method

Definition

Overloads

ContinueWith(Action<Task,Object>, Object, CancellationToken, TaskContinuationOptions, TaskScheduler)

Parameters

Returns

Exceptions

Remarks

Applies to

ContinueWith(Action<Task>, CancellationToken, TaskContinuationOptions, TaskScheduler)

Parameters

Returns

Exceptions

Examples

Remarks

Applies to

ContinueWith(Action<Task,Object>, Object, TaskScheduler)

Parameters

Returns

Exceptions

Remarks

Applies to

ContinueWith(Action<Task,Object>, Object, TaskContinuationOptions)

Parameters

Returns

Exceptions

Remarks

Applies to

ContinueWith(Action<Task,Object>, Object, CancellationToken)

Parameters

Returns

Exceptions

Remarks

Applies to

ContinueWith(Action<Task>)

Parameters

Returns

Exceptions

Examples

Remarks

Applies to

ContinueWith(Action<Task>, TaskContinuationOptions)

Parameters

Returns

Exceptions

Examples

Remarks

Applies to

ContinueWith(Action<Task>, CancellationToken)

Parameters

Returns

Exceptions

Remarks

Applies to

ContinueWith(Action<Task,Object>, Object)

Parameters

Returns

Exceptions

Remarks

Applies to

ContinueWith(Action<Task>, TaskScheduler)

Parameters

Returns

Exceptions

Remarks

Applies to

ContinueWith<TResult>(Func<Task,Object,TResult>, Object, TaskScheduler)

Type Parameters

Parameters

Returns

Exceptions

Remarks

Applies to

ContinueWith<TResult>(Func<Task,Object,TResult>, Object, CancellationToken, TaskContinuationOptions, TaskScheduler)

Type Parameters

Parameters

Returns

Exceptions

Remarks