The document discusses implementing Clean Architecture on Android apps. It describes challenges with traditional architectures like MVP where business logic is mixed with views. Clean Architecture separates concerns into layers - presentation, domain, and data. This makes apps easier to understand, maintain, and test. The domain and presentation layers are independent of frameworks, allowing flexibility. Testing can target each layer individually using tools like Espresso, JUnit, and Mockito. Overall Clean Architecture improves testability and decouples the codebase.

1. Clean Architecture on Android
Benjamin / 班傑明

2. A real-world app
Fragment Adapter
AsyncTask
Network API client
AsyncTask
View
View
Data model

3. Challenge
● Hard to understand/maintain
○ The business logic is mixed in Activity/Fragment/Adapter
○ Loose cohesive, high coupled (低內聚，高耦合)
● Hard to test
○ Cannot fully test the logic in Activity/Fragment/Adapter
○ The UI testing is fragile. (Will build fail if there are content or server-side issues)
○ It costs around 30 minutes to finish our UI testing
○ It’s really frustrating and lose productivity when the tests keep failing (lots of 30+ minutes)

4. MVP
From: http://www.captechconsulting.com/blogs/a-mvp-approach-to-lifecycle-safe-requests-with-retrofit-20-and-rxjava

5. MVP - Interfaces
Program to an interface, not an implementation

6. MVP - View

7. MVP - View

8. MVP - Presenter

9. MVP - Model
● Model? NetworkAPIClient?
● Is MVP an Architecture pattern?

10. MVC/MVP/MVVM is NOT an Architecture
● MVP is not an architectural pattern, it’s only responsible
for the presentation layer (delivery mechanism)

11. The Clean Architecture
From: http://blog.8thlight.com/uncle-bob/2012/08/13/the-clean-architecture.html

12. The Clean Architecture (conti.)
From Robert C Martin - Clean Architecture and Design https://www.youtube.com/watch?v=Nsjsiz2A9mg

13. Interactor - Application specific business rules
● Application specific business rules
● Use cases
● ex: Content aggregation logic for your
app’s landing page, add product to cart, ...
● Regular Java object. No android
framework dependency

14. Repository - Data access
● Application independent business rules
● Business object / Domain model
● Access data by network, memory cache
and disk cache, has Android framework
dependency
● ex: RestAPI, Preference, disk cache

15. Boundary
● No direct dependency between
framework and Interactor
● Interactor can be well tested without
framework

16. MVP - Presentation Layer
● Presenter: Define interfaces for all the UI
interactions [Regular Java object, no
android framework dependency]

17. The Clean Architecture on Android
Fragment Adapter
Network API client
View
View
Presenter Interactor RepositoryViewModel
DataCache
Response
Model

18. The Clean Architecture
● Independent of Frameworks
● Testable
● Allow major decisions(UI, framework, databases) to be
deferred

19. Android application architecture: Get ready for the next
billion! - Google I/O 2016
From https://www.youtube.com/watch?v=70WqJxymPr8

20. Testing
● Presentation layer
○ Expresso
● Domain layer (Use case/Interactor)
○ JUnit + mockito
● Data layer
○ Roboletric + JUnit + mockito

21. Prod
build flavor
Expresso + Mockito
Fragment AdapterView
View
Presenter
InjectionInteractor
Repository

22. Expresso + Mockito (conti.)
Mock
build flavor
Fragment AdapterView
View
Presenter
InjectionMockInteractor
Repository

23. Expresso + Mockito (conti.)

24. Reference
● Robert C Martin - Clean Architecture and Design https://www.youtube.com/watch?v=Nsjsiz2A9mg
● Architecting Android…The clean way? http://fernandocejas.com/2014/09/03/architecting-android-the-clean-way/
● Android Application Architecture. Our journey from standard Activities and AsyncTasks to a modern MVP-based architecture
powered by RxJava. https://labs.ribot.co.uk/android-application-architecture-8b6e34acda65#.zexgfy5tt
● Android Testing (Android Dev Summit 2015) https://www.youtube.com/watch?v=vdasFFfXKOY
● Android Testing Codelab https://codelabs.developers.google.com/codelabs/android-testing/index.html#0
● Advanced Android Espresso http://chiuki.github.io/advanced-android-espresso/#/