Task<TResult> Class

Microsoft Silverlight will reach end of support after October 2021. Learn more.

Represents an asynchronous operation that can return a value.

Inheritance Hierarchy

System.Object
  System.Threading.Tasks.Task
    System.Threading.Tasks.Task<TResult>

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

Syntax

'Declaration
<DebuggerDisplayAttribute("Id = {Id}, Status = {Status}, Method = {DebuggerDisplayMethodDescription}, Result = {DebuggerDisplayResultDescription}")> _
Public Class Task(Of TResult) _
    Inherits Task

[DebuggerDisplayAttribute("Id = {Id}, Status = {Status}, Method = {DebuggerDisplayMethodDescription}, Result = {DebuggerDisplayResultDescription}")]
public class Task<TResult> : Task

Type Parameters

• TResult
  The type of the result produced by this Task<TResult>.

The Task<TResult> type exposes the following members.

Constructors

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

Top

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<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<TResult>.
	Status	Gets the TaskStatus of this Task. (Inherited from Task.)

Top

Methods

	Name	Description
	ContinueWith(Action<Task>)	Creates a continuation that executes asynchronously when the target Task completes. (Inherited from Task.)
	ContinueWith(Action<Task<TResult>>)	Creates a continuation that executes asynchronously when the target Task<TResult> completes.
	ContinueWith(Action<Task>, CancellationToken)	Creates a continuation that executes asynchronously when the target Task completes. (Inherited from Task.)
	ContinueWith(Action<Task>, TaskContinuationOptions)	Creates a continuation that executes according to the specified TaskContinuationOptions. (Inherited from Task.)
	ContinueWith(Action<Task>, TaskScheduler)	Creates a continuation that executes asynchronously when the target Task completes. (Inherited from Task.)
	ContinueWith(Action<Task<TResult>>, CancellationToken)	Creates a continuation that executes asynchronously when the target Task<TResult> completes.
	ContinueWith(Action<Task<TResult>>, TaskContinuationOptions)	Creates a continuation that executes according the condition specified in continuationOptions.
	ContinueWith(Action<Task<TResult>>, TaskScheduler)	Creates a continuation that executes asynchronously when the target Task<TResult> completes.
	ContinueWith(Action<Task>, CancellationToken, TaskContinuationOptions, TaskScheduler)	Creates a continuation that executes according to the specified TaskContinuationOptions. (Inherited from Task.)
	ContinueWith(Action<Task<TResult>>, CancellationToken, TaskContinuationOptions, TaskScheduler)	Creates a continuation that executes according the condition specified in continuationOptions.
	ContinueWith<TResult>(Func<Task, TResult>)	Creates a continuation that executes asynchronously when the target Task completes. (Inherited from Task.)
	ContinueWith<TNewResult>(Func<Task<TResult>, TNewResult>)	Creates a continuation that executes asynchronously when the target Task<TResult> completes.
	ContinueWith<TResult>(Func<Task, TResult>, CancellationToken)	Creates a continuation that executes asynchronously when the target Task completes. (Inherited from Task.)
	ContinueWith<TResult>(Func<Task, TResult>, TaskContinuationOptions)	Creates a continuation that executes according to the condition specified in continuationOptions. (Inherited from Task.)
	ContinueWith<TResult>(Func<Task, TResult>, TaskScheduler)	Creates a continuation that executes asynchronously when the target Task completes. (Inherited from Task.)
	ContinueWith<TNewResult>(Func<Task<TResult>, TNewResult>, CancellationToken)	Creates a continuation that executes asynchronously when the target Task<TResult> completes.
	ContinueWith<TNewResult>(Func<Task<TResult>, TNewResult>, TaskContinuationOptions)	Creates a continuation that executes according the condition specified in continuationOptions.
	ContinueWith<TNewResult>(Func<Task<TResult>, TNewResult>, TaskScheduler)	Creates a continuation that executes asynchronously when the target Task<TResult> completes.
	ContinueWith<TResult>(Func<Task, TResult>, CancellationToken, TaskContinuationOptions, TaskScheduler)	Creates a continuation that executes according to the condition specified in continuationOptions. (Inherited from Task.)
	ContinueWith<TNewResult>(Func<Task<TResult>, TNewResult>, CancellationToken, TaskContinuationOptions, TaskScheduler)	Creates a continuation that executes according the condition specified in continuationOptions.
	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 the Object is reclaimed by garbage collection. (Inherited from Object.)
	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.)

Top

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.)

Top

Remarks

Task<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<TResult> instance that can be used to create tasks for several purposes. For example, to create a Task<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<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.

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.

Thread Safety

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

See Also

Reference

System.Threading.Tasks Namespace

Other Resources

Task Parallel Library Overview

Task Parallelism (Task Parallel Library)