Java FileLock for Reading and Writing

1. Are you aware that locking the file won't keep other processes from touching it unless they also use locks?
2. You have to lock via a writable channel. Get the lock via a RandomAccessFile in "rw" mode and then open your FileInputStream. Make sure to close both!

It would be better if you created the lock using tryLock(0L, Long.MAX_VALUE, true).

This creates a shared lock which is the right thing to do for reading.

tryLock() is a shorthand for tryLock(0L, Long.MAX_VALUE, false), i.e. it requests an exclusive write-lock.