Difference between CompletableFuture, Future and RxJava's Observable

Question

I would like to know the difference between CompletableFuture,Future and Observable RxJava.

What I know is all a

Answer 1

I have been working with Rx Java since 0.9, now at 1.3.2 and soon migrating to 2.x I use this in a private project where I already work on for 8 years.

I wouldn't program without this library at all anymore. In the beginning I was skeptic but it is a complete other state of mind you need to create. Quiete difficult in the beginning. I sometimes was looking at the marbles for hours.. lol

It is just a matter of practice and really getting to know the flow (aka contract of observables and observer), once you get there, you'll hate to do it otherwise.

For me there is not really a downside on that library.

Use case: I have a monitor view that contains 9 gauges (cpu, mem, network, etc...). When starting up the view, the view subscribes itselfs to a system monitor class that returns an observable (interval) that contains all the data for the 9 meters. It will push each second a new result to the view (so not polling !!!). That observable uses a flatmap to simultaneously (async!) fetch data from 9 different sources and zips the result into a new model your view will get on the onNext().

How the hell you gonna do that with futures, completables etc ... Good luck ! :)

Rx Java solves many issues in programming for me and makes in a way a lot easier...

Advantages:

• Statelss !!! (important thing to mention, most important maybe)
• Thread management out of the box
• Build sequences that have their own lifecycle
• Everything are observables so chaining is easy
• Less code to write
• Single jar on classpath (very lightweight)
• Highly concurrent
• No callback hell anymore
• Subscriber based (tight contract between consumer and producer)
• Backpressure strategies (circuit breaker a like)
• Splendid error handling and recovering
• Very nice documentation (marbles <3)
• Complete control
• Many more ...

Disadvantages: - Hard to test