I just recently stumbled across this interesting presentation from Ben Christensen, a Software Engineer in Netflix. Netflix has developed an interesting approach to create a high performance and scalable system. This approach gives Java capability of Functional Programming, before Java 8 with Lambda support went public. They call it ReactiveJava, or RxJava for short. RxJava is a library for creating event-based application, using technique called Observable pattern. More detailed informations are available on their site or their github repo.
I just started learning this, and all I can say is RxJava is a very interesting library. It will take some time to learn (or adopt), but resources below I found very helpful.