Perhaps
The FileOutputStream Class Documentation and the source code:
help to answer this question.
Note that the finalize method may be called automatically by the garbage collector. So, if the programmer forgot to close the stream, when it's no longer in use, the garbage collector may call the finalize method which will close the stream.
Making any sense?
And note that the source code is located in a compressed file named perhaps src.zip or src.jar in the J2SDK installation directory.