Timer.Enabled Property (System.Timers)

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.NET Framework Class Library
Timer.Enabled Property

Gets or sets a value indicating whether the Timer should raise the Elapsed event.

Namespace: System.Timers
Assembly: System (in system.dll)

Syntax
Visual Basic (Declaration)
Public Property Enabled As Boolean
Visual Basic (Usage)
Dim instance As Timer
Dim value As Boolean

value = instance.Enabled

instance.Enabled = value
C#
public bool Enabled { get; set; }
C++
public:
property bool Enabled {
	bool get ();
	void set (bool value);
}
J#
/** @property */
public boolean get_Enabled ()

/** @property */
public void set_Enabled (boolean value)
JScript
public function get Enabled () : boolean

public function set Enabled (value : boolean)

Property Value

true if the Timer should raise the Elapsed event; otherwise, false. The default is false.
Remarks

Setting Enabled to true is the same as calling Start, while setting Enabled to false is the same as calling Stop.

NoteNote

The Elapsed event is raised on a ThreadPool thread, so the event-handling method might run on one thread at the same time that the Enabled property is set to false on another 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 prevent 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.

NoteNote

Some visual designers, such as those in Microsoft Visual Studio, set the Enabled property to true when inserting a new Timer.

Example

The following example creates a Timer that displays "Hello World!" on the console every five seconds.

Use the System.Timers namespace for this example.

Visual Basic
Imports System
Imports System.Timers

Public Class Timer1
    
    Public Shared Sub Main()
        ' Normally, the timer is declared at the class level, so
        ' that it doesn't go out of scope when the method ends.
        ' In this example, the timer is needed only while Main 
        ' is executing. However, KeepAlive must be used at the
        ' end of Main, to prevent the JIT compiler from allowing 
        ' aggressive garbage collection to occur before Main 
        ' ends.
        Dim aTimer As New System.Timers.Timer()

        ' Hook up the Elapsed event for the timer.
        AddHandler aTimer.Elapsed, AddressOf 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()

        ' Keep the timer alive until the end of Main.
        GC.KeepAlive(aTimer)
    End Sub
        
    ' Specify what you want to happen when the Elapsed event is 
    ' raised.
    Private Shared Sub OnTimedEvent(source As Object, e As ElapsedEventArgs)
        Console.WriteLine("Hello World!")
    End Sub
End Class
C#
using System;
using System.Timers;

public class Timer1
{
    public static void Main()
    {
        // Normally, the timer is declared at the class level, so
        // that it doesn't go out of scope when the method ends.
        // In this example, the timer is needed only while Main 
        // is executing. However, KeepAlive must be used at the
        // end of Main, to prevent the JIT compiler from allowing 
        // aggressive garbage collection to occur before Main 
        // ends.
        System.Timers.Timer aTimer = new System.Timers.Timer();

        // Hook up the Elapsed event for the timer.
        aTimer.Elapsed += new ElapsedEventHandler(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();

        // Keep the timer alive until the end of Main.
        GC.KeepAlive(aTimer);
    }
 
    // Specify what you want to happen when the Elapsed event is 
    // raised.
    private static void OnTimedEvent(object source, ElapsedEventArgs e)
    {
        Console.WriteLine("Hello World!");
    }
}
C++
#using <system.dll>

using namespace System;
using namespace System::Timers;

public ref class Timer1
{
public:
   static void Demo()
   {
      // Normally, the timer is declared at the class level, so
      // that it doesn't go out of scope when the method ends.
      // In this example, the timer is needed only while Demo
      // is executing. However, KeepAlive must be used at the
      // end of Demo, to prevent the JIT compiler from allowing 
      // aggressive garbage collection to occur before Demo
      // ends.
      System::Timers::Timer^ aTimer = gcnew System::Timers::Timer;

      // 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();

      // Keep the timer alive until the end of the Demo method.
      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( "Hello World!" );
   }

};

int main()
{
   Timer1::Demo();
}
Platforms

Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.

Version Information

.NET Framework

Supported in: 2.0, 1.1, 1.0
See Also