nio - Java - how to find out if a directory is being used by another process? -

i want use java 7's watchservice monitor changes directory.
seems tries lock folder, , throw exception if fails, not seem provide method of locking before-hand / checking if locked.

i need know if directory being used process or not. since can't lock or open stream (because it's directory), i'm looking more intelligent trying modify , sleeping if failed, or try/catch sleep.

ideally, blocking call until available.

edit: can't seem acquire filelock on folder. when try lock folder, "filenotfoundexception (access denied)". googling suggests can't use object on directory.

registration code:

watchservice watchservice = path.getfilesystem().newwatchservice() path.register(watchservice,                     standardwatcheventkinds.entry_create,                     standardwatcheventkinds.entry_modify,                     standardwatcheventkinds.entry_delete) 

failing scenario:
let's i'm listening folder f new creation.
if sub-folder g created in it, want listen changes in g. however, if create new folder in f (in windows), fail because windows locking folder until name given.

thanks

taken here

file file = new file(filename); filechannel channel = new randomaccessfile(file, "rw").getchannel(); // exclusive lock on whole file filelock lock = channel.lock(); try {     lock = channel.trylock();     // ok. lock } catch (overlappingfilelockexception e) {     // file open else } {     lock.release(); }