Java is one of those OOPs based languages, along with Python and C++, that’s in demand right now. So, if you want to ride the bandwagon and use the language, you must download it on your system. Not ...
(If you're not sure what that means, I'd really recommend just installing 32-bit Java.) If you choose to use Maestro.jar instead, you won't be able to double-click on Maestro or ABC files to open them ...