Problems with cross-threading

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I have an application that has these functions:-
If no data file exists, read the files in a folder and create a new data file.
Read the data file.
Display its contents.

It also has a folder watcher which if it detects a newly created file in the folder, raises an event.
This event reads this file and adds it's details to the data file.

But now the problem:
I then try to re-display its contents.
I get a cross thread problem. Obviously raising the event creates a new thread.
I tried using the Delegate method, but there are too many functions, and the code will (I think) get too confusing.

I thought that I could omit the display routine, and put a button on the form to re-display it, thinking that by pressing the button, I would be back in the original thread. Yes and no. Mostly yes, but an important class no longer initialised, so can I be back on the original thread?

I am using Visual Basic in VS2008

Thanks for any ideas.

Posted 21-May-12 22:56pm

Stuart Nathan

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Stuart Nathan 22-May-12 8:27am

I think the answer is because I used a System.Timer instead of a Windows,Form.Timer

Doing some investigation

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Stuart Nathan · Answer 1 · 2012-05-22T05:50:00

Solution 1

This was the problem.
System.Timer creates a different thread.

Posted 22-May-12 5:50am

Stuart Nathan

Comments

Alan N 22-May-12 12:42pm

Yes, it does by default, but if the SynchronizingObject property is set to a form reference then it will raise the Elapsed event on the form's thread.

Stuart Nathan 22-May-12 13:23pm

Yes I also discovered this. However it was easier to change the declaration. Thanks anyway