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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)

[TimersDescriptionAttribute("TimerEnabled")]
public bool Enabled { get; set; }

Property Value

Type: System.Boolean
true if the Timer should raise the Elapsed event; otherwise, false. The default is false.

ExceptionCondition
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.

NoteNote

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.

NoteNote

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

The following example instantiates a Timer object that fires its Timer.Elapsed event every two seconds (2000 milliseconds), sets up an event handler for the event, and starts the timer. The event handler displays the value of the ElapsedEventArgs.SignalTime property each time it is raised.

// Use this code inside a project created with the Visual C# > Windows Desktop > Console Application template.  
// Replace the code in Program.cs with this code.  

using System;

// To avoid confusion with other Timer classes, this sample always uses the fully-qualified 
// name of System.Timers.Timer instead of a using statement for System.Timers. 

public class Example
{
    private static System.Timers.Timer aTimer;

    public static void Main()
    {
        // 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 timer and set a two second interval.
        aTimer = new System.Timers.Timer();
        aTimer.Interval = 2000;

        // Alternate method: create a Timer with an interval argument to the constructor. 
        //aTimer = new System.Timers.Timer(2000); 

        // Create a timer with a two second interval.
        aTimer = new System.Timers.Timer(2000);

        // Hook up the Elapsed event for the timer. 
        aTimer.Elapsed += OnTimedEvent;

        // Have the timer fire repeated events (true is the default)
        aTimer.AutoReset = true;

        // Start the timer
        aTimer.Enabled = true;

        Console.WriteLine("Press the Enter key to exit the program at any time... ");
        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 static void OnTimedEvent(Object source, System.Timers.ElapsedEventArgs e)
    {
        Console.WriteLine("The Elapsed event was raised at {0}", e.SignalTime);
    }
}

// This example displays output like the following:  
//       Press the Enter key to exit the program at any time...  
//       The Elapsed event was raised at 5/20/2015 8:48:58 PM  
//       The Elapsed event was raised at 5/20/2015 8:49:00 PM  
//       The Elapsed event was raised at 5/20/2015 8:49:02 PM  
//       The Elapsed event was raised at 5/20/2015 8:49:04 PM  
//       The Elapsed event was raised at 5/20/2015 8:49:06 PM 

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1
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