What are the main principles and structure underlying clean architecture in Android app development?

Clean architecture in Android applications is built on separation of concerns and independence of layers, which facilitates testing, maintenance, and scaling. The main principles:

• Layer separation:

  • Entities: business logic and models independent of frameworks.
  • Use Cases: implementation of specific business rules and scenarios.
  • Interface Adapters: data transformation for UI, e.g., ViewModel.
  • Frameworks & Drivers: Android SDK, databases, external libraries.

• Dependencies point inward: outer layers depend on inner layers, but not vice versa.

• Dependency inversion: inner layers are unaware of external implementation details, using abstractions.

• Separation of UI from business logic: UI does not contain business rules, only display and interaction.

Example project structure:

app/
├── data/          # Repositories, data sources
├── domain/        # Entities and use cases
├── presentation/  # ViewModel, UI
└── di/            # Dependency setup

This approach increases modularity and makes application maintenance easier.