Timer::Enabled Property
Namespace: System.Timers
Assembly: System (in System.dll)
| Exception | Condition |
|---|---|
| ObjectDisposedException | This property cannot be set because the timer has been disposed. |
| ArgumentException | The Interval property was set to a value greater than Int32::MaxValue before the timer was enabled. |
Setting Enabled to true is the same as calling Start, while setting Enabled to false is the same as calling Stop.
Note |
|---|
The signal to raise the Elapsed event is always queued for execution on a ThreadPool thread. This might result in the Elapsed event being raised after the Enabled property is set to false. The code example for the Stop method shows one way to work around this race condition. |
If Enabled is set to true and AutoReset is set to false, the Timer raises the Elapsed event only once, the first time the interval elapses.
If the interval is set after the Timer has started, the count is reset. For example, if you set the interval to 5 seconds and then set the Enabled property to true, the count starts at the time Enabled is set. If you reset the interval to 10 seconds when count is 3 seconds, the Elapsed event is raised for the first time 13 seconds after Enabled was set to true.
Note |
|---|
Some visual designers, such as those in Microsoft Visual Studio, set the Enabled property to true when inserting a new Timer. |
The following code example sets up an event handler for the Timer::Elapsed event, creates a timer, and uses the Enabled event to start the timer. The event handler displays the SignalTime property each time it is raised.
#using <system.dll> using namespace System; using namespace System::Timers; public ref class Timer1 { private: static System::Timers::Timer^ aTimer; public: static void Demo() { // Normally, the timer is declared at the class level, // so that it stays in scope as long as it is needed. // If the timer is declared in a long-running method, // KeepAlive must be used to prevent the JIT compiler // from allowing aggressive garbage collection to occur // before the method ends. You can experiment with this // by commenting out the class-level declaration and // uncommenting the declaration below; then uncomment // the GC::KeepAlive(aTimer) at the end of the method. //System::Timers::Timer^ aTimer; // Create a new Timer with Interval set to 10 seconds. aTimer = gcnew System::Timers::Timer( 10000 ); // Hook up the Elapsed event for the timer. aTimer->Elapsed += gcnew ElapsedEventHandler( Timer1::OnTimedEvent ); // Set the Interval to 2 seconds (2000 milliseconds). aTimer->Interval = 2000; aTimer->Enabled = true; Console::WriteLine("Press the Enter key to exit the program."); Console::ReadLine(); // If the timer is declared in a long-running method, use // KeepAlive to prevent garbage collection from occurring // before the method ends. //GC::KeepAlive(aTimer); } private: // Specify what you want to happen when the Elapsed event is // raised. static void OnTimedEvent( Object^ source, ElapsedEventArgs^ e ) { Console::WriteLine( "The Elapsed event was raised at {0}", e->SignalTime ); } }; int main() { Timer1::Demo(); } /* This code example produces output similar to the following: Press the Enter key to exit the program. The Elapsed event was raised at 5/20/2007 8:42:27 PM The Elapsed event was raised at 5/20/2007 8:42:29 PM The Elapsed event was raised at 5/20/2007 8:42:31 PM ... */
Windows 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.
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