Android uses a heavily modifed Linux kernel with seems not to provide patches back to upstream, and an userland software abstraction layer that is not even fully Java-compliant, because it only uses the dialect ("language") but not a compatible VM implementation.

This was obviously done by Google to avoid licensing issues with then current-Java IP holder Sun, which pissed off Sun because they first thought during Google's initial press release that "hey, even Google supports Java, and now even in mobile business!". Where is this deviated mess a "Linux paradise"?