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Thread.ApartmentState Property

Gets or sets the apartment state of this thread.

[Visual Basic]
Public Property ApartmentState As ApartmentState
[C#]
public ApartmentState ApartmentState {get; set;}
[C++]
public: __property ApartmentState get_ApartmentState();
public: __property void set_ApartmentState(ApartmentState);
[JScript]
public function get ApartmentState() : ApartmentState;
public function set ApartmentState(ApartmentState);

Property Value

One of the ApartmentState values. The initial value is Unknown.

Exceptions

Exception Type Condition
ArgumentException An attempt is made to set this property to a state that is not a valid apartment state (a state other than single-threaded apartment (STA) or multithreaded apartment (MTA)).

Remarks

The ApartmentState property marks a thread to indicate that it will execute in a single-threaded or multithreaded apartment. This property can be set when the thread is in the Unstarted or Running thread state; however, it can be set only once for a thread. If the property has not been set, it returns Unknown.

Example

[Visual Basic, C#, C++] The following code example demonstrates how to set the apartment state of a thread.

[Visual Basic] 
Imports Microsoft.VisualBasic
Imports System
Imports System.Threading

Public Class ApartmentTest

    Shared Sub Main()
    
        Dim newThread As Thread = New Thread(AddressOf ThreadMethod)
        newThread.ApartmentState = ApartmentState.MTA

        ' The following line is ignored since 
        ' ApartmentState can only be set once.
        newThread.ApartmentState = ApartmentState.STA

        Console.WriteLine("ThreadState: {0}, ApartmentState: {1}", _
            newThread.ThreadState, newThread.ApartmentState)

        newThread.Start()

        ' Wait for newThread to start and go to sleep.
        Thread.Sleep(300)
        Try
            ' This causes an exception since newThread is sleeping.
            newThread.ApartmentState = ApartmentState.STA
        Catch stateException As ThreadStateException
            Console.WriteLine(vbCrLf & "{0} caught:" & vbCrLf & _
                "Thread is not In the Unstarted or Running state.", _
                stateException.GetType().Name)
            Console.WriteLine("ThreadState: {0}, ApartmentState: " & _
                "{1}", newThread.ThreadState, newThread.ApartmentState)
        End Try

    End Sub

    Shared Sub ThreadMethod()
        Thread.Sleep(1000)
    End Sub

End Class

[C#] 
using System;
using System.Threading;

class ApartmentTest
{
    static void Main()
    {
        Thread newThread = 
            new Thread(new ThreadStart(ThreadMethod));
        newThread.ApartmentState = ApartmentState.MTA;

        // The following line is ignored since 
        // ApartmentState can only be set once.
        newThread.ApartmentState = ApartmentState.STA;

        Console.WriteLine("ThreadState: {0}, ApartmentState: {1}", 
            newThread.ThreadState, newThread.ApartmentState);

        newThread.Start();

        // Wait for newThread to start and go to sleep.
        Thread.Sleep(300);
        try
        {
            // This causes an exception since newThread is sleeping.
            newThread.ApartmentState = ApartmentState.STA;
        }
        catch(ThreadStateException stateException)
        {
            Console.WriteLine("\n{0} caught:\n" +
                "Thread is not in the Unstarted or Running state.", 
                stateException.GetType().Name);
            Console.WriteLine("ThreadState: {0}, ApartmentState: {1}",
                newThread.ThreadState, newThread.ApartmentState);
        }
    }

    static void ThreadMethod()
    {
        Thread.Sleep(1000);
    }
}

[C++] 
#using <mscorlib.dll>
using namespace System;
using namespace System::Threading;

__gc class ApartmentTest
{
public :
    static void ThreadMethod()
    {
        Thread::Sleep(1000);
    }
};

void main()
{
    Thread* newThread = 
        new Thread(new ThreadStart(0, &ApartmentTest::ThreadMethod));
        newThread->ApartmentState = ApartmentState::MTA;

        // The following line is ignored since 
        // ApartmentState can only be set once.
        newThread->ApartmentState = ApartmentState::STA;

        Console::WriteLine(S"ThreadState: {0}, ApartmentState: {1}", 
            __box(newThread->ThreadState)->ToString(),
            __box(newThread->ApartmentState)->ToString());

    newThread->Start();

    // Wait for newThread to start and go to sleep.
    Thread::Sleep(300);
    try
    {
        // This causes an exception since newThread is sleeping.
        newThread->ApartmentState = ApartmentState::STA;
    }
    catch(ThreadStateException* stateException)
    {
        Console::WriteLine(S"\n{0} caught:\n"
            S"Thread is not in the Unstarted or Running state.",
            stateException->GetType()->Name);
        Console::WriteLine(S"ThreadState: {0}, ApartmentState: {1}", 
            __box(newThread->ThreadState)->ToString(),
            __box(newThread->ApartmentState)->ToString());
    }
}

[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button Language Filter in the upper-left corner of the page.

Requirements

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family

See Also

Thread Class | Thread Members | System.Threading Namespace | ThreadState

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