Which third party libraries is good to learn for android development?

Question

As above. which libraries are good to learn and why (please give some description and comment about it). Also I am interested which libraries are good from job point of view.

Answer 1

(assuming you use Java, no idea if it works with Kotlin) RxJava - reactive programming, it can be a bit hard to grasp its concepts but observables can make your code more concise and more effective
Retrofit - Http library, not that difficult to learn but to my knowledge requires an API endpoint to connect to
Dagger - dependency injection, much better than Singleton patterns
ButterKnife (possibly with ButterKnifeZelezny) - easy binding of UI elements in code
If you don't want to fiddle with RecyclerView Adapters, FastAdapter works pretty well
You could also use Room/Realm for database access
For loading and displaying images, I think that Glide works well (though you can use Picasso if you want a smaller package)