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ElapsedEventHandler Delegate

Represents the method that will handle the Elapsed event of a Timer.

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

public delegate void ElapsedEventHandler(
	Object sender,
	ElapsedEventArgs e
)

Parameters

sender
Type: System.Object

The source of the event.

e
Type: System.Timers.ElapsedEventArgs

An ElapsedEventArgs object that contains the event data.

When you create an ElapsedEventHandler delegate, you identify the method that will handle the event. To associate the event with your event handler, add an instance of the delegate to the event. The event handler is called whenever the event occurs, unless you remove the delegate. For more information about event handler delegates, see Handling and Raising Events.

The following code example sets up an event handler for the Timer.Elapsed event, creates a timer, and starts the timer. The event handler has the same signature as the ElapsedEventHandler delegate. The event handler displays the SignalTime property each time it is raised.

using System;
using System.Timers;

public class Timer1
{
    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 with a ten second interval.
        aTimer = new System.Timers.Timer(10000);

        // 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();

        // 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);
    }

    // Specify what you want to happen when the Elapsed event is  
    // raised. 
    private static void OnTimedEvent(object source, ElapsedEventArgs e)
    {
        Console.WriteLine("The Elapsed event was raised at {0}", e.SignalTime);
    }
}

/* 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
...
 */

.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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