Writing to files on windows

Question

Hi
I have a jvm that will write some text to a file on a windows file system. There is some another process that will read it. This other process is beyond my control i.e. it wont be written by me and won't be java.
How do i ensure that my jvm that writes to this file only when no other process is reading and also blocks on the write to prevent the other process trying to read when a write is in progress?
I have read about FileChannel and FileLock and have tried writing a test app. My FileChannel tryLock call always seems to succeed, meaning that my write then goes ahead even when the other process is reading, which can cause this read to then fail.
Any ideas? I know there are lots of hits for FileChannel and FileLock on this forum but nothing matching my requirements that i can see.
appreciate any advice
thanks

Answer 1

Locks tend to be [advisory versus mandatory|http://java.sun.com/javase/6/docs/api/java/nio/channels/FileLock.html], so unless both processes are using locks, they don't work.
One way to keep the reader from reading while you are writing is to write to a different fille in the same folder (say fileXXXXXXXX.tmp) then when you are done writing, rename it (say fileXXXXXXXX.txt).
To keep from over-writing the file while another process is reading an earlier version.... hmmm.. include a unique timestamp in the name of the file?