Java should be available through the standard package repository on your system.
I don't think the official NX client supports ARM. I have used OpenNX before together with the official NX server software (see "NX client for Efika MX" entry here):
with very good results. You did not specify what your exact requirements were for your specific application, and why this would not work.
Johan Dams, Genesi USA Inc.
Director, Software Engineering
Yep, I have a blog... PurpleAlienPlanet