Check if file is already open

Question

I need to write a custom batch File renamer. I've got the bulk of it done except I can't figure out how to check if a file is already open. I'm just using the java.io.File package and there is a canWrite() method but that doesn't seem to test if the file is in use by another program. Any ideas on how I can make this work?

Answer 1

I don't think you'll ever get a definitive solution for this, the operating system isn't necessarily going to tell you if the file is open or not.

You might get some mileage out of java.nio.channels.FileLock, although the javadoc is loaded with caveats.

Answer 2

If file is in use FileOutputStream fileOutputStream = new FileOutputStream(file); returns java.io.FileNotFoundException with 'The process cannot access the file because it is being used by another process' in the exception message.