How to reset a timer in C#?

Question

There are three Timer classes that I am aware of, System.Threading.Timer, System.Timers.Timer, and System.Windows.Forms.Timer, but none of these have a .Reset() function which would reset the current elapsed time to 0.

Is there a BCL class that has this functionality? Is there a non-hack way of doing it? (I thought perhaps changing the time limit on it might reset it) Thought on how hard it would be to reimplement a Timer class that had this functionality, or how to do it reliably with one of the BCL classes?

Answer 1

i do this

//Restart the timer
queueTimer.Enabled = true;

Answer 2

For a Timer (System.Windows.Forms.Timer).

The .Stop, then .Start methods worked as a reset.

Answer 3

I just assigned a new value to the timer:

mytimer.Change(10000, 0); // reset to 10 seconds

it works fine for me.

at the top of the code define the timer: System.Threading.Timer myTimer;

if (!active)
        {
            myTimer= new System.Threading.Timer(new TimerCallback(TimerProc));
        }
        myTimer.Change(10000, 0);
        active = true;

private void TimerProc(object state)
    {
        // The state object is the Timer object.
        System.Threading.Timer t = (System.Threading.Timer)state;
        t.Dispose();
        Console.WriteLine("The timer callback executes.");
        active = false;
        //action to do when timer is back to zero
    }

Answer 4

For System.Timers.Timer, according to MSDN documentation, http://msdn.microsoft.com/en-us/library/system.timers.timer.enabled.aspx:

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.

So,

    const double TIMEOUT = 5000; // milliseconds

    aTimer = new System.Timers.Timer(TIMEOUT);
    aTimer.Start();     // timer start running

    :
    :

    aTimer.Interval = TIMEOUT;  // restart the timer

Answer 5

You could write an extension method called Reset(), which

• calls Stop()-Start() for Timers.Timer and Forms.Timer
• calls Change for Threading.Timer

Answer 6

For clarity since some other comments are incorrect, when using System.Timers setting Enabled to true will reset the elapsed time. I just tested the behavior with the below:

Timer countDown= new Timer(3000);

Main()
{
    TextBox.TextDidChange += TextBox_TextDidChange;
    countdown.Elapsed += CountDown_Elapsed;
}

void TextBox_TextDidChange(Object sender, EventArgs e)
{
    countdown.Enabled = true;
}

void CountDown_Elapsed(object sender, EventArgs e)
{
    System.Console.WriteLine("Elapsed");
}

I would input text to the text box repeatedly and the timer would only run 3 seconds after the last keystroke. It's hinted at in the docs as well, as you'll see: calling Timers.Start() simply sets Enabled to true.

And to be sure, which I should've just went straight to from the beginning, you'll see in the .NET reference source that if enabling an already Enabled timer it calls the private UpdateTimer() method, which internally calls Change().