Thread.TrySetApartmentState(ApartmentState) Method
Important
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Sets the apartment state of a thread before it is started.
public:
bool TrySetApartmentState(System::Threading::ApartmentState state);
public bool TrySetApartmentState (System.Threading.ApartmentState state);
member this.TrySetApartmentState : System.Threading.ApartmentState -> bool
Public Function TrySetApartmentState (state As ApartmentState) As Boolean
- state
- ApartmentState
The new apartment state.
true
if the apartment state is set; otherwise, false
.
.NET Core and .NET 5+ only: In all cases on macOS and Linux.
state
is not a valid apartment state.
The thread was started and has terminated, or the call is not being made from the thread's context while the thread is running.
The following code example demonstrates the GetApartmentState, SetApartmentState, and TrySetApartmentState methods. The code example creates a thread. Before the thread is started, GetApartmentState displays the initial ApartmentState.Unknown state and SetApartmentState changes the state to ApartmentState.STA. The TrySetApartmentState method then returns false
when attempting to change the state to ApartmentState.MTA because the apartment state is already set. If the same operation had been attempted with SetApartmentState, InvalidOperationException would have been thrown.
After the thread is started, the TrySetApartmentState method is used again. This time it throws ThreadStateException because the thread has already been started.
using namespace System;
using namespace System::Threading;
void ThreadProc()
{
Thread::Sleep(2000);
};
void main()
{
Thread^ t = gcnew Thread(gcnew ThreadStart(ThreadProc));
Console::WriteLine("Before setting apartment state: {0}",
t->GetApartmentState());
t->SetApartmentState(ApartmentState::STA);
Console::WriteLine("After setting apartment state: {0}",
t->GetApartmentState());
bool result = t->TrySetApartmentState(ApartmentState::MTA);
Console::WriteLine("Try to change state: {0}", result);
t->Start();
Thread::Sleep(500);
try
{
t->TrySetApartmentState(ApartmentState::STA);
}
catch (ThreadStateException^)
{
Console::WriteLine("ThreadStateException occurs " +
"if apartment state is set after starting thread.");
}
t->Join();
}
/* This code example produces the following output:
Before setting apartment state: Unknown
After setting apartment state: STA
Try to change state: False
ThreadStateException occurs if apartment state is set after starting thread.
*/
using System;
using System.Threading;
class Example
{
public static void Main()
{
Thread t = new Thread(ThreadProc);
Console.WriteLine("Before setting apartment state: {0}",
t.GetApartmentState());
t.SetApartmentState(ApartmentState.STA);
Console.WriteLine("After setting apartment state: {0}",
t.GetApartmentState());
bool result = t.TrySetApartmentState(ApartmentState.MTA);
Console.WriteLine("Try to change state: {0}", result);
t.Start();
Thread.Sleep(500);
try
{
t.TrySetApartmentState(ApartmentState.STA);
}
catch (ThreadStateException)
{
Console.WriteLine("ThreadStateException occurs " +
"if apartment state is set after starting thread.");
}
t.Join();
}
public static void ThreadProc()
{
Thread.Sleep(2000);
}
}
/* This code example produces the following output:
Before setting apartment state: Unknown
After setting apartment state: STA
Try to change state: False
ThreadStateException occurs if apartment state is set after starting thread.
*/
open System.Threading
let threadProc () = Thread.Sleep 2000
let t = Thread threadProc
printfn $"Before setting apartment state: {t.GetApartmentState()}"
t.SetApartmentState ApartmentState.STA
printfn $"After setting apartment state: {t.GetApartmentState()}"
let result = t.TrySetApartmentState ApartmentState.MTA
printfn $"Try to change state: {result}"
t.Start()
Thread.Sleep 500
try
t.TrySetApartmentState ApartmentState.STA |> ignore
with :? ThreadStateException ->
printfn "ThreadStateException occurs if apartment state is set after starting thread."
t.Join()
// This code example produces the following output:
// Before setting apartment state: Unknown
// After setting apartment state: STA
// Try to change state: False
// ThreadStateException occurs if apartment state is set after starting thread.
Imports System.Threading
Module Example
Sub Main()
Dim t As New Thread(AddressOf ThreadProc)
Console.WriteLine("Before setting apartment state: {0}", _
t.GetApartmentState())
t.SetApartmentState(ApartmentState.STA)
Console.WriteLine("After setting apartment state: {0}", _
t.GetApartmentState())
Dim result As Boolean = _
t.TrySetApartmentState(ApartmentState.MTA)
Console.WriteLine("Try to change state: {0}", result)
t.Start()
Thread.Sleep(500)
Try
t.TrySetApartmentState(ApartmentState.STA)
Catch ex As ThreadStateException
Console.WriteLine("ThreadStateException occurs " & _
"if apartment state is set after starting thread.")
End Try
t.Join()
End Sub
Sub ThreadProc()
Thread.Sleep(2000)
End Sub
End Module
' This code example produces the following output:
'
'Before setting apartment state: Unknown
'After setting apartment state: STA
'Try to change state: False
'ThreadStateException occurs if apartment state is set after starting thread.
New threads are initialized as ApartmentState.MTA if their apartment state has not been set before they are started. Apartment state must be set before a thread is started.
Nota
The main application thread is initialized to ApartmentState.MTA by default. The only way to set the apartment state of the main application thread to ApartmentState.STA is to apply the STAThreadAttribute attribute to the entry point method.
The TrySetApartmentState method, along with the GetApartmentState method and the SetApartmentState method, replaces the ApartmentState property.
Prodotto | Versioni |
---|---|
.NET | Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9 |
.NET Framework | 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
.NET Standard | 2.0, 2.1 |
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