Correct - I programmed nothing in java, but ultimately the python ran in a python interpreter, implemented in java. So what java classes does the j-python interpreter call for file IO?

For those unfamiliar with Java's java.io.File package, consider yourselves lucky. In comparison to Perl's File modules, Java's API is clumsy, slow, and incomplete. The text processing piece is a no brainer; clearly Perl has the upper hand.

Irrelevant ? I can't really say, I don't program in java.