Search:

That's a lot of code, and chances are that nobody will want to wade through it. You're welcome to wait and hope that somebody does, but you'd be more likely to get help if you narrowed the problem...

I'd start with a google search. The first page of results seems extremely promising.

Hate to disagree with a seasoned vet, but I see two problems with this:

Assuming MainTextArea (er, mainTextArea?) is a JTextArea, you don't want to be updating it off of the EDT, right? Actually,...

Still sounds like a job for SwingWorker to me...

I think you're looking for SwingWorker. Google is your friend.