SparkFun is having a special IoT deal: Free Shipping on the MiP Robotic Platform $99.95 (while supplies last!)
This robot comes with documentation and apps are available to control it with an iOS and Android smartphone. But, with a bit of tweaking, I'm guessing you could also get it to work with a Raspberry Pi and a Java app... Just sayin'...
Here's a quote:
Description: The MiP Robotic Platform
Great as an IoT stocking stuffer!