start a timer from different thread in c#

问题:

Hi i have stepped into some problem related to timer. hope somebody can help..

1. I have a windows form containing a button
2. when i click on that button i start a parameterised thread

Thread thread1 = new Thread(new ParameterizedThreadStart( execute2));
thread1.Start(externalFileParams);

1. the code inside the thread executes very well
2. at the last line of this thread i start a timer

.

public void execute2(Object ob)
{
    if (ob is ExternalFileParams)
    {
        if (boolean_variable== true)
          executeMyMethod();//this also executes very well if condition is true
        else
        {
            timer1.enabled = true;
            timer1.start();
            }
        }
    }
}

5 but the tick event of the timer is not fired

I am working on VS2008 3.5 framework. I have dragged the timer from toolbox and set its Interval to 300 also tried to set Enabled true/false method is timer1_Tick(Object sender , EventArgs e) but its not fired

can anybody suggest what I am doing wrong?

回答1:

You could try to start the timer this way:

Add in form constructor this:

System.Timers.Timer aTimer = new System.Timers.Timer();
 aTimer.Elapsed += new ElapsedEventHandler(OnTimedEvent);
 // Set the Interval to 1 second.
 aTimer.Interval = 1000;

Add this method to Form1:

 private static void OnTimedEvent(object source, ElapsedEventArgs e)
 {
   //do something with the timer
 }

On button click event add this:

aTimer.Enabled = true;

This timer is already threaded so no need to start a new thread.

回答2:

It is true what Matías Fidemraizer says. But, there is a work around...

When you have a control on your form that is invokable (eg. a statusbar), just invoke that one!

C# Code sample:

private void Form1_Load(object sender, EventArgs e)
{
    Thread sampleThread = new Thread(delegate()
    {
        // Invoke your control like this
        this.statusStrip1.Invoke(new MethodInvoker(delegate()
        {
            timer1.Start();
        }));
    });
    sampleThread.Start();
}

private void timer1_Tick(object sender, EventArgs e)
{
    MessageBox.Show("I just ticked!");
}

回答3:

System.Windows.Forms.Timer works in a single-threaded application.

Check this link:

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

Remarks says:

A Timer is used to raise an event at user-defined intervals. This Windows timer is designed for a single-threaded environment where UI threads are used to perform processing. It requires that the user code have a UI message pump available and always operate from the same thread, or marshal the call onto another thread.

Read more "Remarks" section and you'll find that Microsoft recommends that you use this timer synchronizing it with the UI thread.

回答4:

I would use a BackgroundWorker (instead of a raw thread). The main thread would subscribe to the worker's RunWorkerCompleted event: The event fires in your main thread when the thread completes. Use this event handler to restart your timer.