Hi,
in my application I start many threads, and them open files. Those threads are like daemons waiting for changes in those files.
If i.e. a critical error is detected, is valid to finish the app a "System.exit()", or do I have to close every file and stop every thread?
Thanx
Do all the close down using 'shutdown hooks'. Google will find you the information you need to use them.
I was under the impression that System.exit() would close the files and stop the threads? Was I wrong?
Yes, Runtime.addShutdownHook(Thread hook) and related methods exist in version 1.4.2. Do use your favourite search engine for more information.
OK, shutdown hooks allow you to make a perfect shutdown, I'll use them if necessary.
But what happens with the threads and opened files if I just make a System.exit() ?
Let's assume I just want to release those resources, no other processing. Perhaps I get all that done with the System.exit().
System resources (file handles, sockets etc) get released back to the system when Java exits. Streams and files don't get closed nicely so you may loose any data that has been buffered before being written.
> System resources (file handles, sockets etc) get
> released back to the system when Java exits. Streams
> and files don't get closed nicely so you may loose
> any data that has been buffered before being written.
If you are writing to (any of) those files, that is. And haven't called flush(). No problem if you're only reading.
I'm trying to complement the answer to the original poster. I am not trying to argue that just calling System.exit() is a nice and clean solution.
If you do setDaemon(true) on these background threads then they won't stop the program from terminating normally without System.exit(();
