About 10 years ago, I used something of that description with a Lego Mindstorms robot. The project site (looking at the Wikipedia page, we must've been using Lejos NXT) had API documentation like the Sun site did, links to their cut-down JDK, etc. I don't remember if we flashed the controller brick with a custom firmware, or if the JRE was linked into the class files produces by compilation, but it worked nicely for our purposes.

For reference, the NXT v1 brick has an ARM-based Atmel microcontroller with a clock of ~55MHz, 256KB of flash, and 64KB of RAM, along with a smaller ATMega4 microcontroller.

Oh, this takes me back to my university days where I spent time with Lejos [0] on an RCX brick (32 kilobytes of usable space).

I recall using Eclipse for development and I am sure the build process involved uploading the JVM and program code via a USB infrared interface.

Have to say that I preferred using "Not Quite C" [1] due to it having a simpler syntax and intuitive support for cooperative multitasking.

[0] http://www.lejos.org/ [1] http://bricxcc.sourceforge.net/nqc/

I had a lab partner, and Java was our shared language. I don't remember the decision process that went into choosing our language, but I'm sure that was a big part of it.

Actually, looking at NQC's page, they don't support the NXT, just the RCX. That certainly would've been the killer for us, there.

E.g.:

https://www.oracle.com/java/technologies/embedded.html

http://electronicdesign.com/dev-tools/5-things-you-need-know...

http://www.javaworld.com/article/2077249/client-side-java/cl...

http://www.drdobbs.com/jvm/its-a-java-embedded-world/2400059...

Well, with 512 MB of RAM you're just fine with standard Java and frameworks. That's still A LOT of memory.