What does HackerNews think of beakerx?
Beaker Extensions for Jupyter Notebook
https://github.com/twosigma/beakerx
It has some quirks, but it works amazingly well really, esp. with the enhanced widgets BeakerX gives you.
I do lots of ML in Groovy using beakerx [0] which is pretty much the last thing anybody would expect but it works great.
https://github.com/twosigma/beakerx
It'll give you Java, Scala, Kotlin, and Groovy kernels.
I would particularly suggest the Groovy kernels (and Groovy in general) for munging around data with Java. I actually prefer it to pandas/Python except for the less rich ecosystem around machine learning / stats / deep learning.
NB: For the SPA-like side, have a look at Micronaut which will work nicely with Groovy / Kotlin / Java and then you don't need Node, just interface Micronaut directly with your React code.
You can read more about it here, too: http://beakernotebook.com
Jane Street is also pretty awesome - they open sourced their in-house standard library for OCaml, called Base: https://github.com/janestreet/base (they use a lot of OCaml).