Question

Because val is similar to final in Java, should most Java object references be marked as final as using val is good practice in Scala?

Answer 1

Certainly it’s good practice to make class variables final in Java, encouraging immutability wherever possible.

As for whether local variables — method parameters, etc. — should be marked final when not necessary, that’s a question of style. Personally, I feel it tends to clutter things when used, unless it’s otherwise necessary (e.g. to make a variable accessible in an anonymous inner class).