proper architecture of Android App, best practices, estabilished solutions ?

Hi

I'm experienced java developer, i know how to use IDE, Java, Spring, Dependency Injection, SQL, XML, JSON, REST, WebServices, SSL etc.. I'm looking for advanced tutorials about android app architectures.
I've started learning Android about 5-6 years ago (And 2.x), i had a long break, now i want to learn more...but...

I'm searching for online courses, looking at developer.android.com ,but still i can see only 'simple description' of every component (like Intent, Activity, Fragment, Views etc.)
without information how to create proper app (with proper layout/architecture etc.) - so i don't have to reinvent the wheel !

I'm able to create Android App with few Activites, database, few screens, fragments etc.
but i feel that if i add a little more it'll be a mess. That's why i'm looking for 'best practices' about 'laying out' android apps

For example, if i want to create standalone pc app (service or desktop app), instead of creating everything from scratch, i would use Spring Boot, or Tomcat with Spring MVC/Core and Dependency Injection etc.
i would layer my app - controllers, services, repositories, model
- estabilished way / best practices.

but i can't find anything like that for Android App. Do you know anything about such tutorials/examples/materials ?

Regards,
Lukasz

— modified on Aug 3, 2017, 2:17:53 PM