Today many systems,software written in Java(JVM languages). Recent popularity of Haskell,Erlang,Scala is attributed to their functional features. Scala- Actor model,Erlang-lightweight processes,List comprehensions etc.
What are the advantages of FP in Java over features offered by these languages ?
The main advantage of the ability to program in functional style in Java compared to those other languages is that we get to use Java in a better way if we're already using it.
In other words, I would not be choosing Java to do functional programming, for an arbitrary application on hand, if I truly had a choice of these languages you've mentioned.
Instead I would be choosing to program functionally moving forward in systems that are currently programmed in Java. In other words, my interest in functional programming in
Java is not about how I would use it compared to other languages, but why I would use it in comparison to how I have been using Java before 1.8.