A Linux Distro is one Based on the linux kernel. The user interface whether it is java based QT based or GTK or python has nothing to do with linux except that it is on top. You could say that ubuntu is more Gnome than it is linux and it is still a flawed statement. Java cannot run on its own. It must have a kernel (linux, unix, dos etc. etc.) for it to be usable just like any other UI. So Android IS a linux distro with a Java desktop environment.