C# show timer in textbox

Question

I'm trying to make a timer run in a textbox and I haven't had any luck.

This is the code I'm using:

private static System.Timers.Timer timer;
...
private void StartBtn_Click(object sender, EventArgs e)
{
    timer = new System.Timers.Timer(1000);
    timer.Elapsed += new ElapsedEventHandler(OnTimedEvent);
    timer.Enabled = true;
}
...
private void OnTimedEvent(object source, ElapsedEventArgs e)
{
    TimeTb.Text = e.SignalTime.ToString();
}

But nothing happens.

I tried this:

private void OnTimedEvent(object source, ElapsedEventArgs e)
{
    MessageBox.Show(e.SignalTime.ToString(), 
    "Question", MessageBoxButtons.YesNo, MessageBoxIcon.Question);
}

And it worked fine. Anyone know why it isn't working with my textbox?

You must have another long running process that's actually running on the UI thread. This code would work. — Mike Perrenoud, Sep 23 '13 at 12:17
@RameshRajendran, for a `MessageBox` to work it would have to be a Windows application. — Mike Perrenoud, Sep 23 '13 at 12:18
Assuming you're in **WinForms**, have you tried with `TimeTb.Update();`? — Alessandro D'Andria, Sep 23 '13 at 12:23

score 4 · Accepted Answer · edited Sep 23 '13 at 12:28

4

The Elapsed Event runs on a different Thread then the UI. Its not allowed to manipulate UI Objects from a different thread and an Exception should surface in your EventHandler. Since you don't handle Exceptions there you won't notice it.

In StartBtn_Click set the SynchronizingObject Property of the Timer to this (the form). Then the elapsed Event will be synchronized with the main thread.

edited Sep 23 '13 at 12:28

King King

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answered Sep 23 '13 at 12:26

Ralf

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score 1 · Answer 2 · answered Sep 23 '13 at 12:18

1

May be you should start the timer first.

Take a look at:

http://msdn.microsoft.com/en-us/library/system.timers.timer.start.aspx

So add:

timer.Start();

answered Sep 23 '13 at 12:18

Stofkn

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I thought `timer.Enabled = true;` did that :O – Johan Hjalmarsson Sep 23 '13 at 12:19
@Litari, no, `Start` must be called. – Mike Perrenoud Sep 23 '13 at 12:19
@Litari if you were never calling start how could "it worked fine" be the case? – Squirrel5853 Sep 23 '13 at 12:22
1

There might be an exception being thrown if the Timer is running on a different thread. Have you tried using the Windows.Forms.Timer class? http://msdn.microsoft.com/en-us/library/system.windows.forms.timer.aspx – Ric Sep 23 '13 at 12:23
1

@Secret Squirrel: In the link: "You can also start timing by setting Enabled to true." – Johan Hjalmarsson Sep 23 '13 at 12:25
As in the documentation page, it says ***You can also start timing by setting Enabled to true.*** – King King Sep 23 '13 at 12:29
Setting enabled to true will start the timer. – Justin Harvey Sep 23 '13 at 12:33
@Litari Thanks now I have learnt something :D, although I did suspect as my question stated how could it have worked before without using `start` method http://stackoverflow.com/questions/1012948/using-system-windows-forms-timer-start-stop-versus-enabled-true-false – Squirrel5853 Sep 23 '13 at 16:20

score 1 · Answer 3 · answered Sep 23 '13 at 12:26

Put a try catch around OnTimedEvent and see if there are any issues with threading. If there are, try using the System.Windows.Forms.Timer which can resolve the issues of cross threading.

http://msdn.microsoft.com/en-us/library/system.windows.forms.timer.aspx

As stated:

Implements a timer that raises an event at user-defined intervals. This timer is optimized for use in Windows Forms applications and must be used in a window.

score 1 · Answer 4 · answered Sep 23 '13 at 12:28

Your OnTimedEvent callback will not be called on the UI thread, so you will get an exception in there trying to set the textbox text. So you need to change the event handler to look like this:

private void OnTimedEvent(object source, ElapsedEventArgs e)
{
  if (TimeTb.InvokeRequired)
  {
    TimeTb.Invoke((MethodInvoker)delegate
                {
                  OnTimedEvent(source, e);
                });

  }

  TimeTb.Text = e.SignalTime.ToString();
}

Ramesh Rajendran · Answer 5 · 2013-09-23T12:30:49.170

0

you could do something like

private void Button_Click(object sender, RoutedEventArgs e)
    {
        this._timer = new DispatcherTimer();
        this._timer.Interval = TimeSpan.FromMilliseconds(1);
        this._timer.Tick += new EventHandler(_timer_Tick);
        _timer.Start();
    }

void _timer_Tick(object sender, EventArgs e)
{
    t= t.Add(TimeSpan.FromMilliseconds(1));
    textBox.Text = t.Hours + ":" + t.Minutes + ":" + t.Seconds + ":" + t.Milliseconds;
}

Edit :

How to add Assembly: WindowsBase

enter image description here

edited Sep 23 '13 at 12:30

answered Sep 23 '13 at 12:20

Ramesh Rajendran

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what do I have to include to be able to use DispatcherTimer? `using System.Windows.Threading` doesn't seem to exist. – Johan Hjalmarsson Sep 23 '13 at 12:26
Use Assembly: WindowsBase – Ramesh Rajendran Sep 23 '13 at 12:30

score 0 · Answer 6 · edited May 23 '17 at 11:58

0

Maybe using Application.DoEvents(); after TimeTb.Text = e.SignalTime.ToString(); would work, though using it would not be recommended (Use of Application.DoEvents()).

edited May 23 '17 at 11:58

Community

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answered Sep 23 '13 at 12:20

Anderson Pimentel

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C# show timer in textbox

6 Answers6