Windows apps
Collapse the table of content
Expand the table of content

TaskFactory.StartNew Method (Action<Object>, Object)

 

Creates and starts a Task.

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

public Task StartNew(
	Action<object> action,
	object state
)

Parameters

action
Type: System.Action<Object>

The action delegate to execute asynchronously.

state
Type: System.Object

An object containing data to be used by the action delegate.

Return Value

Type: System.Threading.Tasks.Task

The started Task.

Exception Condition
ArgumentNullException

The action argument is null.

Calling StartNew is functionally equivalent to creating a Task using one of its constructors and then calling the Start method to schedule it for execution.

Starting with the .NET Framework 4.5, you can use the Run method with an Action object as a quick way to call StartNew with default parameters. For more information and code examples, see Task.Run vs Task.Factory.StartNew in the Parallel Programming with .NET blog.

The following example defines an array of 6-letter words. Each word is then passed to an Action<T> delegate, which scrambles the word and displays the original word and its scrambled version.

using System;
using System.Collections.Generic;
using System.Threading.Tasks;

public class Example
{
   public static void Main()
   {
      var tasks = new List<Task>();
      Random rnd = new Random();
      Object lockObj = new Object();
      String[] words6 = { "reason", "editor", "rioter", "rental",
                          "senior", "regain", "ordain", "rained" };

      foreach (var word6 in words6)
         tasks.Add(Task.Factory.StartNew( (word) => { Char[] chars = word.ToString().ToCharArray();
                                                      double[] order = new double[chars.Length];
                                                      lock (lockObj) {
                                                         for (int ctr = 0; ctr < order.Length; ctr++)
                                                             order[ctr] = rnd.NextDouble();
                                                      }
                                                      Array.Sort(order, chars);
                                                      Console.WriteLine("{0} --> {1}", word,
                                                                        new String(chars));
                                                    }, word6));

      Task.WaitAll(tasks.ToArray());
   }
}
// The example displays output like the following:
//    regain --> irnaeg
//    ordain --> rioadn
//    reason --> soearn
//    rained --> rinade
//    rioter --> itrore
//    senior --> norise
//    rental --> atnerl
//    editor --> oteird

Note that the example initializes a single random number generator, which is protected by a lock. For the need of a lock, see "The System.Random class and thread safety" in the Random class topic.

Universal Windows Platform
Available since 8
.NET Framework
Available since 4.0
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 5.0
Windows Phone Silverlight
Available since 8.0
Windows Phone
Available since 8.1
Return to top
Show:
© 2016 Microsoft