Task(TResult) Class (System.Threading.Tasks)

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.NET Framework Class Library

Task<(Of <(TResult>)>) Class

[This documentation is for preview only, and is subject to change in later releases. Blank topics are included as placeholders.]

Represents an asynchronous operation that can return a value.

Inheritance Hierarchy

System..::.Object
System.Threading.Tasks..::.Task
System.Threading.Tasks..::.Task<(Of <(TResult>)>)

Namespace: System.Threading.Tasks
Assembly: mscorlib (in mscorlib.dll)

Syntax

Visual Basic

<HostProtectionAttribute(SecurityAction.LinkDemand, Synchronization := True,  _
	ExternalThreading := True)> _
Public Class Task(Of TResult) _
	Inherits Task

[HostProtectionAttribute(SecurityAction.LinkDemand, Synchronization = true, 
	ExternalThreading = true)]
public class Task<TResult> : Task

Visual C++

[HostProtectionAttribute(SecurityAction::LinkDemand, Synchronization = true, 
	ExternalThreading = true)]
generic<typename TResult>
public ref class Task : public Task

[<HostProtectionAttribute(SecurityAction.LinkDemand, Synchronization = true, 
    ExternalThreading = true)>]
type Task<'TResult> =  
    class
        inherit Task
    end

Type Parameters

TResult: The type of the result produced by this Task<(Of <(TResult>)>).

The Task<(Of <(TResult>)>) type exposes the following members.

Constructors

	Name	Description
	Task<(Of <(TResult>)>)(Func<(Of <(TResult>)>))	Initializes a new Task<(Of <(TResult>)>) with the specified function.
	Task<(Of <(TResult>)>)(Func<(Of <(TResult>)>), CancellationToken)	Initializes a new Task<(Of <(TResult>)>) with the specified function.
	Task<(Of <(TResult>)>)(Func<(Of <(TResult>)>), TaskCreationOptions)	Initializes a new Task<(Of <(TResult>)>) with the specified function and creation options.
	Task<(Of <(TResult>)>)(Func<(Of <(Object, TResult>)>), Object)	Initializes a new Task<(Of <(TResult>)>) with the specified function and state.
	Task<(Of <(TResult>)>)(Func<(Of <(TResult>)>), CancellationToken, TaskCreationOptions)	Initializes a new Task<(Of <(TResult>)>) with the specified function and creation options.
	Task<(Of <(TResult>)>)(Func<(Of <(Object, TResult>)>), Object, CancellationToken)	Initializes a new Task<(Of <(TResult>)>) with the specified action, state, and options.
	Task<(Of <(TResult>)>)(Func<(Of <(Object, TResult>)>), Object, TaskCreationOptions)	Initializes a new Task<(Of <(TResult>)>) with the specified action, state, and options.
	Task<(Of <(TResult>)>)(Func<(Of <(Object, TResult>)>), Object, CancellationToken, TaskCreationOptions)	Initializes a new Task<(Of <(TResult>)>) with the specified action, state, and options.

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Properties

	Name	Description
	AsyncState	Gets the state object supplied when the Task was created, or null if none was supplied. (Inherited from Task.)
	CreationOptions	Gets the TaskCreationOptions used to create this task. (Inherited from Task.)
	Exception	Gets the AggregateException that caused the Task to end prematurely. If the Task completed successfully or has not yet thrown any exceptions, this will return null. (Inherited from Task.)
	Factory	Provides access to factory methods for creating Task<(Of <(TResult>)>) instances.
	Id	Gets a unique ID for this Task instance. (Inherited from Task.)
	IsCanceled	Gets whether this Task instance has completed execution due to being canceled. (Inherited from Task.)
	IsCompleted	Gets whether this Task has completed. (Inherited from Task.)
	IsFaulted	Gets whether the Task completed due to an unhandled exception. (Inherited from Task.)
	Result	Gets the result value of this Task<(Of <(TResult>)>).
	Status	Gets the TaskStatus of this Task. (Inherited from Task.)

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Methods

	Name	Description
	ConfigureAwait	Configures an awaiter used to await this Task<(Of <(TResult>)>).
	ContinueWith(Action<(Of <(Task>)>))	Creates a continuation that executes asynchronously when the target Task completes. (Inherited from Task.)
	ContinueWith(Action<(Of <(Task<(Of <(TResult>)>)>)>))	Creates a continuation that executes asynchronously when the target Task<(Of <(TResult>)>) completes.
	ContinueWith(Action<(Of <(Task>)>), CancellationToken)	Creates a continuation that executes asynchronously when the target Task completes. (Inherited from Task.)
	ContinueWith(Action<(Of <(Task>)>), TaskContinuationOptions)	Creates a continuation that executes according to the specified TaskContinuationOptions. (Inherited from Task.)
	ContinueWith(Action<(Of <(Task>)>), TaskScheduler)	Creates a continuation that executes asynchronously when the target Task completes. (Inherited from Task.)
	ContinueWith(Action<(Of <(Task, Object>)>), Object)	Creates a continuation that executes when the target Task completes. (Inherited from Task.)
	ContinueWith(Action<(Of <(Task<(Of <(TResult>)>)>)>), CancellationToken)	Creates a continuation that executes asynchronously when the target Task<(Of <(TResult>)>) completes.
	ContinueWith(Action<(Of <(Task<(Of <(TResult>)>)>)>), TaskContinuationOptions)	Creates a continuation that executes according the condition specified in continuationOptions.
	ContinueWith(Action<(Of <(Task<(Of <(TResult>)>)>)>), TaskScheduler)	Creates a continuation that executes asynchronously when the target Task<(Of <(TResult>)>) completes.
	ContinueWith(Action<(Of <(Task<(Of <(TResult>)>), Object>)>), Object)	Creates a continuation that executes when the target Task<(Of <(TResult>)>) completes.
	ContinueWith(Action<(Of <(Task, Object>)>), Object, CancellationToken)	Creates a continuation that executes when the target Task completes. (Inherited from Task.)
	ContinueWith(Action<(Of <(Task, Object>)>), Object, TaskContinuationOptions)	Creates a continuation that executes when the target Task completes. (Inherited from Task.)
	ContinueWith(Action<(Of <(Task, Object>)>), Object, TaskScheduler)	Creates a continuation that executes when the target Task completes. (Inherited from Task.)
	ContinueWith(Action<(Of <(Task<(Of <(TResult>)>), Object>)>), Object, CancellationToken)	Creates a continuation that executes when the target Task<(Of <(TResult>)>) completes.
	ContinueWith(Action<(Of <(Task<(Of <(TResult>)>), Object>)>), Object, TaskContinuationOptions)	Creates a continuation that executes when the target Task<(Of <(TResult>)>) completes.
	ContinueWith(Action<(Of <(Task<(Of <(TResult>)>), Object>)>), Object, TaskScheduler)	Creates a continuation that executes when the target Task<(Of <(TResult>)>) completes.
	ContinueWith(Action<(Of <(Task>)>), CancellationToken, TaskContinuationOptions, TaskScheduler)	Creates a continuation that executes according to the specified TaskContinuationOptions. (Inherited from Task.)
	ContinueWith(Action<(Of <(Task<(Of <(TResult>)>)>)>), CancellationToken, TaskContinuationOptions, TaskScheduler)	Creates a continuation that executes according the condition specified in continuationOptions.
	ContinueWith(Action<(Of <(Task, Object>)>), Object, CancellationToken, TaskContinuationOptions, TaskScheduler)	Creates a continuation that executes when the target Task completes. (Inherited from Task.)
	ContinueWith(Action<(Of <(Task<(Of <(TResult>)>), Object>)>), Object, CancellationToken, TaskContinuationOptions, TaskScheduler)	Creates a continuation that executes when the target Task<(Of <(TResult>)>) completes.
	ContinueWith<(Of <(TResult>)>)(Func<(Of <(Task, TResult>)>))	Creates a continuation that executes asynchronously when the target Task completes. (Inherited from Task.)
	ContinueWith<(Of <(TNewResult>)>)(Func<(Of <(Task<(Of <(TResult>)>), TNewResult>)>))	Creates a continuation that executes asynchronously when the target Task<(Of <(TResult>)>) completes.
	ContinueWith<(Of <(TResult>)>)(Func<(Of <(Task, TResult>)>), CancellationToken)	Creates a continuation that executes asynchronously when the target Task completes. (Inherited from Task.)
	ContinueWith<(Of <(TResult>)>)(Func<(Of <(Task, TResult>)>), TaskContinuationOptions)	Creates a continuation that executes according to the condition specified in continuationOptions. (Inherited from Task.)
	ContinueWith<(Of <(TResult>)>)(Func<(Of <(Task, TResult>)>), TaskScheduler)	Creates a continuation that executes asynchronously when the target Task completes. (Inherited from Task.)
	ContinueWith<(Of <(TResult>)>)(Func<(Of <(Task, Object, TResult>)>), Object)	Creates a continuation that executes when the target Task completes. (Inherited from Task.)
	ContinueWith<(Of <(TNewResult>)>)(Func<(Of <(Task<(Of <(TResult>)>), TNewResult>)>), CancellationToken)	Creates a continuation that executes asynchronously when the target Task<(Of <(TResult>)>) completes.
	ContinueWith<(Of <(TNewResult>)>)(Func<(Of <(Task<(Of <(TResult>)>), TNewResult>)>), TaskContinuationOptions)	Creates a continuation that executes according the condition specified in continuationOptions.
	ContinueWith<(Of <(TNewResult>)>)(Func<(Of <(Task<(Of <(TResult>)>), TNewResult>)>), TaskScheduler)	Creates a continuation that executes asynchronously when the target Task<(Of <(TResult>)>) completes.
	ContinueWith<(Of <(TNewResult>)>)(Func<(Of <(Task<(Of <(TResult>)>), Object, TNewResult>)>), Object)	Creates a continuation that executes when the target Task<(Of <(TResult>)>) completes.
	ContinueWith<(Of <(TResult>)>)(Func<(Of <(Task, Object, TResult>)>), Object, CancellationToken)	Creates a continuation that executes when the target Task completes. (Inherited from Task.)
	ContinueWith<(Of <(TResult>)>)(Func<(Of <(Task, Object, TResult>)>), Object, TaskContinuationOptions)	Creates a continuation that executes when the target Task completes. (Inherited from Task.)
	ContinueWith<(Of <(TResult>)>)(Func<(Of <(Task, Object, TResult>)>), Object, TaskScheduler)	Creates a continuation that executes when the target Task completes. (Inherited from Task.)
	ContinueWith<(Of <(TNewResult>)>)(Func<(Of <(Task<(Of <(TResult>)>), Object, TNewResult>)>), Object, CancellationToken)	Creates a continuation that executes when the target Task<(Of <(TResult>)>) completes.
	ContinueWith<(Of <(TNewResult>)>)(Func<(Of <(Task<(Of <(TResult>)>), Object, TNewResult>)>), Object, TaskContinuationOptions)	Creates a continuation that executes when the target Task<(Of <(TResult>)>) completes.
	ContinueWith<(Of <(TNewResult>)>)(Func<(Of <(Task<(Of <(TResult>)>), Object, TNewResult>)>), Object, TaskScheduler)	Creates a continuation that executes when the target Task<(Of <(TResult>)>) completes.
	ContinueWith<(Of <(TResult>)>)(Func<(Of <(Task, TResult>)>), CancellationToken, TaskContinuationOptions, TaskScheduler)	Creates a continuation that executes according to the condition specified in continuationOptions. (Inherited from Task.)
	ContinueWith<(Of <(TNewResult>)>)(Func<(Of <(Task<(Of <(TResult>)>), TNewResult>)>), CancellationToken, TaskContinuationOptions, TaskScheduler)	Creates a continuation that executes according the condition specified in continuationOptions.
	ContinueWith<(Of <(TResult>)>)(Func<(Of <(Task, Object, TResult>)>), Object, CancellationToken, TaskContinuationOptions, TaskScheduler)	Creates a continuation that executes when the target Task completes. (Inherited from Task.)
	ContinueWith<(Of <(TNewResult>)>)(Func<(Of <(Task<(Of <(TResult>)>), Object, TNewResult>)>), Object, CancellationToken, TaskContinuationOptions, TaskScheduler)	Creates a continuation that executes when the target Task<(Of <(TResult>)>) completes.
	Dispose()()()	Releases all resources used by the current instance of the Task class. (Inherited from Task.)
	Dispose(Boolean)	Disposes the Task, releasing all of its unmanaged resources. (Inherited from Task.)
	Equals(Object)	Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
	Finalize	Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
	GetAwaiter	Gets an awaiter used to await this Task<(Of <(TResult>)>).
	GetHashCode	Serves as a hash function for a particular type. (Inherited from Object.)
	GetType	Gets the Type of the current instance. (Inherited from Object.)
	MemberwiseClone	Creates a shallow copy of the current Object. (Inherited from Object.)
	RunSynchronously()()()	Runs the Task synchronously on the current TaskScheduler. (Inherited from Task.)
	RunSynchronously(TaskScheduler)	Runs the Task synchronously on the TaskScheduler provided. (Inherited from Task.)
	Start()()()	Starts the Task, scheduling it for execution to the current TaskScheduler. (Inherited from Task.)
	Start(TaskScheduler)	Starts the Task, scheduling it for execution to the specified TaskScheduler. (Inherited from Task.)
	ToString	Returns a string that represents the current object. (Inherited from Object.)
	Wait()()()	Waits for the Task to complete execution. (Inherited from Task.)
	Wait(CancellationToken)	Waits for the Task to complete execution. (Inherited from Task.)
	Wait(Int32)	Waits for the Task to complete execution. (Inherited from Task.)
	Wait(TimeSpan)	Waits for the Task to complete execution. (Inherited from Task.)
	Wait(Int32, CancellationToken)	Waits for the Task to complete execution. (Inherited from Task.)

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Extension Methods

	Name	Description
	AsAsyncAction	Returns a Windows Runtime asynchronous action that represents a started task. (Defined by WindowsRuntimeSystemExtensions.)
	AsAsyncOperation<(Of <(TResult>)>)	Returns a Windows Runtime asynchronous operation that represents a started task that returns a result. (Defined by WindowsRuntimeSystemExtensions.)
	DispatcherOperationWait()()()	Overloaded. Waits indefinitely for the underlying DispatcherOperation to complete. (Defined by TaskExtensions.)
	DispatcherOperationWait(TimeSpan)	Overloaded. Waits for the specified amount of time for the underlying DispatcherOperation to complete. (Defined by TaskExtensions.)
	IsDispatcherOperationTask	Returns a value that indicates whether this Task is associated with a DispatcherOperation. (Defined by TaskExtensions.)

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Explicit Interface Implementations

	Name	Description
	IAsyncResult..::.AsyncWaitHandle	Gets a WaitHandle that can be used to wait for the task to complete. (Inherited from Task.)
	IAsyncResult..::.CompletedSynchronously	Gets an indication of whether the operation completed synchronously. (Inherited from Task.)

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Remarks

Task<(Of <(TResult>)>) instances may be created in a variety of ways. The most common approach is by using the task's Factory property to retrieve a TaskFactory<(Of <(TResult>)>) instance that can be used to create tasks for several purposes. For example, to create a Task<(Of <(TResult>)>) that runs a function, the factory's StartNew method may be used:

// C# 
var t = Task<int>.Factory.StartNew(() => GenerateResult());

' Visual Basic
Dim t = Task(Of Integer).Factory.StartNew(Function() GenerateResult())

For more complete examples, see Task Parallelism (Task Parallel Library).

The Task<(Of <(TResult>)>) class also provides constructors that initialize the task but that do not schedule it for execution. For performance reasons, the StartNew method should be the preferred mechanism for creating and scheduling computational tasks, but for scenarios where creation and scheduling must be separated, the constructors may be used, and the task's Start method may then be used to schedule the task for execution at a later time.

Note
The HostProtectionAttribute attribute applied to this type or member has the following Resources property value: Synchronization \| ExternalThreading. 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.

Note

The HostProtectionAttribute attribute applied to this type or member has the following Resources property value: Synchronization | ExternalThreading. 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.

Version Information

.NET Framework

Supported in: 4.5, 4

.NET Framework Client Profile

Supported in: 4

Platforms

Windows 8 Consumer Preview, Windows Server 8 Beta, Windows 7, Windows Server 2008 SP2, 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.

Thread Safety

All members of Task<(Of <(TResult>)>), except for Dispose, are thread-safe and may be used from multiple threads concurrently.

Reference

System.Threading.Tasks Namespace

Other Resources

Task Parallel Library

Task Parallelism (Task Parallel Library)