If you are interested in using the Push 2 from Java, Clojure, or another JVM language, there is some good news.
Last week Ableton finally released documentation on how to control the Push 2 hardware, both from MIDI for the majority of its capabilities, and as a raw USB serial device to draw on the graphical display.
I had been waiting impatiently (and pestering them) for this information since they announced the device last fall, so I pounced on the specs, and have created an open-source Java library, Wayang, that makes it extremely easy to draw on the display.
If you are going down that path, you may also be interested in some of my Clojure code for driving a fluid tactile interface on the Push. That is more intimately intertwined with Afterglow, my live-coding environment for light shows, but could still be mined for useful pieces. There is a polished driver for the original Push, and a barely-started port to the Push 2 that will be changing rapidly this week. There is also illustrated documentation of how the interface works from a user perspective.
Cheers, and happy hacking!