Question

I’m trying to create a Windows Form application that searches for a string and has three possible scenarios:

1. String 1 found – wait
2. String 2 found – stop
3. Else – Perform action and wait 1 minute

I am encountering my problem only on the times when it is expected to wait. When this happens, the newTimer_Tick starts to tick every second. I have tried disabling the timer when it ticks and a few other things but none appeared to work. Below is the code:

public void Action(string result)
{
    if (result.Contains("string1"))
    {
        // Check again in 10 + x seconds
        int n = new Random().Next(0, 5000);
        int newtime = 10000 + n;
        newTimer.Tick += new EventHandler(newTimer_Tick);
        newTimer.Interval = newtime;
        newTimer.Enabled = true;
    }
    else if (result.Contains("string2"))
    {
        // Turn off
        newTimer.Enabled = false;
    }
    else
    {
        // Perform action and tick again in 1min + x seconds
        action1();

        int n = new Random().Next(0, 5000);
        int newtime = 600000 + n;
        newTimer.Tick += new EventHandler(newTimer_Tick);
        newTimer.Interval = newtime;
        newTimer.Enabled = true;
    }
}

private void newTimer_Tick(object sender, EventArgs e)
{
    Action( result );
}

What have I done wrong?

Answer 1

Each time the following line is called, an new instance of the event handler newTimerTick is added to the invocation list for the Tick event:

newTimer.Tick += new System.EventHandler(newTimer_Tick);

So every time the time tick goes off newTimerTick is going to be called multiple times, which is going to give you unexpected results.

Configure your event handler once only. In the constructor would be a sensible place.