How to get through Java to Scala?

Question

Java

1) how best to comprehend the basics of OOP and FP: in parallel or sequentially?
2) Is it practiced to replace Java with Scala in commercial development and, accordingly, master Scala in the process of work? (no work experience, so I don't know if it's possible)

Answer 1

Although Scala runs on jvm, it has a different ideology. If you don't plan to work with Java, then focus on Scala and FP. Just keep in mind that there are "millions" of libraries in Java and most likely you will use them when working with Scala, so at least a superficial understanding of Java is still needed.

Answer 2

It makes no sense. Scala is little used. Java 8 introduced lambdas.

Answer 3

Scala is quite widespread in corporate programming.
I easily managed to master it with little or no experience in using java (though with decent experience in Haskell and C ++, which helped a lot), when it was necessary to use libraries available only for jvm. And then it was not a big deal to find a decent job in Scala without java.
In addition to lambdas, Scala has pattern matching and a good REPL. The latter makes learning third-party java libraries much easier than using java (even with the best IDEs ;-)).