Represents the method that executes on a Thread.
Assembly: mscorlib (in mscorlib.dll)
<ComVisibleAttribute(True)> _ Public Delegate Sub ThreadStart
[ComVisibleAttribute(true)] public delegate void ThreadStart()
[ComVisibleAttribute(true)] public delegate void ThreadStart()
[<ComVisibleAttribute(true)>] type ThreadStart = delegate of unit -> unit
When a managed thread is created, the method that executes on the thread is represented by a ThreadStart delegate or a ParameterizedThreadStart delegate that is passed to the Thread constructor. The thread does not begin executing until the Thread.Start method is called. Execution begins at the first line of the method represented by the ThreadStart or ParameterizedThreadStart delegate.
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Visual Basic and C# users can omit the ThreadStart or ParameterizedThreadStart delegate constructor when creating a thread. In Visual Basic, use the AddressOf operator when passing your method to the Thread constructor; for example, Dim t As New Thread(AddressOf ThreadProc). In C#, simply specify the name of the thread procedure. The compiler selects the correct delegate constructor. |
[C++]
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In version 2.0 of the .NET Framework, creating a ThreadStart delegate for a static method in C++ requires only one parameter: the address of the callback method, qualified by the class name. In earlier versions two parameters were required when creating a delegate for a static method: zero (null) and the method address. For an instance method, all versions require two parameters: the instance variable and the method address. |
The following code example shows the syntax for creating and using a ThreadStart delegate with an instance method and with a static method.
For another simple example that demonstrates how to create a ThreadStart delegate, see the Thread.Start() method overload. For more information about thread creation, see Creating Threads and Passing Data at Start Time.
Imports System Imports System.Threading Public Class Test <MTAThread> _ Shared Sub Main() ' To start a thread using a static thread procedure, use the ' class name and method name when you create the ThreadStart ' delegate. Visual Basic expands the AddressOf expression ' to the appropriate delegate creation syntax: ' New ThreadStart(AddressOf Work.DoWork) ' Dim newThread As New Thread(AddressOf Work.DoWork) newThread.Start() ' To start a thread using an instance method for the thread ' procedure, use the instance variable and method name when ' you create the ThreadStart delegate. Visual Basic expands ' the AddressOf expression to the appropriate delegate ' creation syntax: ' New ThreadStart(AddressOf w.DoMoreWork) ' Dim w As New Work() w.Data = 42 newThread = new Thread(AddressOf w.DoMoreWork) newThread.Start() End Sub End Class Public Class Work Public Shared Sub DoWork() Console.WriteLine("Static thread procedure.") End Sub Public Data As Integer Public Sub DoMoreWork() Console.WriteLine("Instance thread procedure. Data={0}", Data) End Sub End Class ' This code example produces the following output (the order ' of the lines might vary): ' 'Static thread procedure. 'Instance thread procedure. Data=42
using System; using System.Threading; class Test { static void Main() { // To start a thread using a static thread procedure, use the // class name and method name when you create the ThreadStart // delegate. Beginning in version 2.0 of the .NET Framework, // it is not necessary to create a delegate explicitly. // Specify the name of the method in the Thread constructor, // and the compiler selects the correct delegate. For example: // // Thread newThread = new Thread(Work.DoWork); // ThreadStart threadDelegate = new ThreadStart(Work.DoWork); Thread newThread = new Thread(threadDelegate); newThread.Start(); // To start a thread using an instance method for the thread // procedure, use the instance variable and method name when // you create the ThreadStart delegate. Beginning in version // 2.0 of the .NET Framework, the explicit delegate is not // required. // Work w = new Work(); w.Data = 42; threadDelegate = new ThreadStart(w.DoMoreWork); newThread = new Thread(threadDelegate); newThread.Start(); } } class Work { public static void DoWork() { Console.WriteLine("Static thread procedure."); } public int Data; public void DoMoreWork() { Console.WriteLine("Instance thread procedure. Data={0}", Data); } } /* This code example produces the following output (the order of the lines might vary): Static thread procedure. Instance thread procedure. Data=42 */
using namespace System; using namespace System::Threading; ref class Work { public: static void DoWork() { Console::WriteLine( "Static thread procedure." ); } int Data; void DoMoreWork() { Console::WriteLine( "Instance thread procedure. Data={0}", Data ); } }; int main() { // To start a thread using an instance method for the thread // procedure, specify the object as the first argument of the // ThreadStart constructor. // Work^ w = gcnew Work; w->Data = 42; ThreadStart^ threadDelegate = gcnew ThreadStart( w, &Work::DoMoreWork ); Thread^ newThread = gcnew Thread( threadDelegate ); newThread->Start(); // To start a thread using a static thread procedure, specify // only the address of the procedure. This is a change from // earlier versions of the .NET Framework, which required // two arguments, the first of which was null (0). // threadDelegate = gcnew ThreadStart( &Work::DoWork ); newThread = gcnew Thread( threadDelegate ); newThread->Start(); } /* This code example produces the following output (the order of the lines might vary): Static thread procedure. Instance thread procedure. Data=42 */
.NET Framework
Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0.NET Framework Client Profile
Supported in: 4, 3.5 SP1Portable Class Library
Supported in: Portable Class LibraryWindows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
Reference
Other Resources
Beginning with the .NET Framework 2.0, C++ code requires only one argument to create a delegate for a static method. (See the note in Remarks.) Please let me know where you found the MSDN example that uses two arguments, so I can correct it. Thx!
Glenn Hackney
CLR Documentation Team
Note