Java was one step along the way, but let's say it had adequate representation of heavy-handed tools we already had in C/C++ that made some forms of concurrency somewhat easier. But it was still some ways from promoting concurrency in that threads were pretty costly and you still depended on locking to move state between threads. And it isn't like CSP hadn't been thought of.
After about 20 years of programming Java and 5-6 years programming Go I wouldn't really list concurrency as a main feature of Java. Because you kind of go at it the way you go at it in C/C++. I think someone who has programmed (for instance) Erlang would feel much the same way.
Java exposes the low-level details of parallelism, but it also allows for high level abstractions on top. Thanks to that there are indeed libraries like Akka to provide something for those that prefer the actor model, but also clojure with its immutable data structure-using concurrency and anything in between like reactive libs. Of course concurrency has never been easy in practice so the low level details are hard to get right, but they are there in a sane and easy to use way, so if not the main point of the language, I would absolutely mention it as one of the most important plus features.
Java was one step along the way, but let's say it had adequate representation of heavy-handed tools we already had in C/C++ that made some forms of concurrency somewhat easier. But it was still some ways from promoting concurrency in that threads were pretty costly and you still depended on locking to move state between threads. And it isn't like CSP hadn't been thought of.
After about 20 years of programming Java and 5-6 years programming Go I wouldn't really list concurrency as a main feature of Java. Because you kind of go at it the way you go at it in C/C++. I think someone who has programmed (for instance) Erlang would feel much the same way.