Actually that was my very first thought, but I couldn’t find any (foolproof) instruction on how to install Java in a jail. For instance I came across
this thread, which doesn’t sound very promising to me. Can you point me at an How-to?
Alternatively I have now Ubuntu running under VirtualBox inside a jail (Hackintosh Mac OS X just didn’t work well), the problem though is that I can’t get any screen res higher than 640x480 in Ubuntu respectively the VNC screen, despite having installed the VirtualBox Guest Additions in Ubuntu 14.04.