App Architecture Skill
Quick Start
MVVM Pattern
@HiltViewModel
class UserViewModel @Inject constructor(
private val repository: UserRepository
) : ViewModel() {
private val _state = MutableLiveData<UiState>()
val state: LiveData<UiState> = _state
fun loadUser(id: Int) {
viewModelScope.launch {
_state.value = repository.getUser(id)
}
}
}
Repository Pattern
interface UserRepository {
suspend fun getUser(id: Int): User
}
class UserRepositoryImpl(
private val dao: UserDao,
private val api: UserApi
) : UserRepository {
override suspend fun getUser(id: Int): User {
return dao.getUser(id) ?: api.fetchUser(id)
}
}
Dependency Injection (Hilt)
@Module
@InstallIn(SingletonComponent::class)
object RepositoryModule {
@Provides
fun provideUserRepository(dao: UserDao, api: UserApi): UserRepository {
return UserRepositoryImpl(dao, api)
}
}
Key Concepts
MVVM Benefits
- Lifecycle awareness
- Configuration change handling
- Separation of concerns
- Testability
Clean Architecture Layers
- Domain: Business rules
- Application: Use cases
- Presentation: UI
- Infrastructure: Data sources
SOLID Principles
- S: Single Responsibility
- O: Open/Closed
- L: Liskov Substitution
- I: Interface Segregation
- D: Dependency Inversion
Best Practices
✅ Dependency injection ✅ Interface-based design ✅ Layered architecture ✅ Single responsibility ✅ Testable code