Concurrent file write in Java on Windows

Question

What happens when you concurrently open two (or more) FileOutputStreams on the same file?

The Java API says this:

Some platforms, in particula

Answer 1

I would be wary of letting the OS determine file status for you (since this is OS-dependent). If you've got a shared resource I would restrict access to it using a Re-entrant lock

Using this lock means one thread can get the resource (file) and write to it. The next thread can check for this lock being held by another thread, and/or block indefinitely until the first thread releases it.

Windows (I think) would restrict two processes writing to the same file. I don't believe Unix would do the same.