[java] Files within files within files.

I need some pointers as to how to go about creating a filesystem within a file. What I want to do is to put files (and preferably directories) into a single file, packing them together (preferbly with LZW compression too). So basically I want to be able to make a .zip file. Surely there must be an easy way of doing this in code in Java without having to write my own code to all this? For interest, the reason I want to do this is that I want to make an editor for a game (this is all in my head atm) that can create levels, sprites, weapons, items, particle systems and other cool things and then create single files (.mod or something) that can describe the game and that can be read by the game engine. I''m probably going way over my abilities here and I''ll start with something simple but this something useful that I would like to know anyway. I know there is a way to do this in C++ using MFC so surely there must be some class in Java can do it, I just haven''t found it yet =)