Scala vs Java if you're NOT going to use Spark? I'm facing some indecision when choosing how to allocate my scarce learning time for the next few months between Scala and Java. 

I would like help objectively understanding the practical tradeoffs.

The reason I am interested in Java is that I think some of my production, frequently refreshed, forecasts and analyses at work would run much faster in Java (compared to R or Python) and by becoming more proficient in Java I would enable myself to work on interesting side projects, such as non-Data-Science apps I'd like to develop. Currently I've taken a couple of Java courses, but I need much more education and practice to master it.

The reason I started considering learning Scala is very similar -- I figured that the statistical/ML orientation would make it good for my work as a Data Scientist, and since it is based on Java I would be getting practice at work that helps me with my side-interest in Java, even though there are a few major differences such as functional vs. imperative and traits vs. interfaces.

It seems like a lot of the advantages of Scala revolve around integration with Spark. I am thinking that this should be the tipping point for my decision, because my team is not currently using Spark and I don't have a good enough reason to request it. However, I thought I should ask here so that I don't waste too much time if Scala is still a better choice.

For the purposes of this question please ignore alternatives such as Python, R, Julia, etc (I've eliminated those from consideration for other reasons, such as already being sufficiently familiar with them for my use cases).
This is a bit off topic for this SE, or maybe opinion-based, but, I work in this field and I'd recommend Scala.

No I would not characterize Scala as a "stats-oriented" Java. I'd describe it as what you get if you asked 3 people to design "Java 11" and then used all of their ideas at once.

Java 8 remains great, but Scala fully embraces just about all the good ideas from languages that you'd want, like type safety and closures and functional paradigms, and a more elaborate types/generics system, down to more syntactic sugar conveniences like case classes and lazy vals. Plus you get to run everything in the same JVM and interoperate with any Java libraries. 

The price is complexity: understanding all of Scala is a lot more difficult than all of Java. And some bits of Scala maybe were a bridge too far. And, the tooling ecosystem isn't great IMHO in comparison to the standard Java tools. But there again you can for example use Maven instead of SBT. But you can mostly avoid the parts of Scala that are complex if you don't need them. Designing Scala libraries takes a lot of skill and know-how; just developing run-of-the-mill code in Scala does not.

From a productivity perspective, once you're used to Scala, you'll be more productive. If you're an experienced Java dev, I actually think you'll appreciate Scala. I have not liked any other JVM language, which tend to be sort of one-issue languages that change lots of stuff for marginal gains.

Certainly, for analytics, the existence of Spark argues for Scala. You'll use it eventually.