Building Clean Architecture in Android

Clean Architecture has become a cornerstone of modern Android development. In this guide, I'll walk you through implementing it in a real-world project.

What is Clean Architecture?

Clean Architecture, introduced by Robert C. Martin (Uncle Bob), is a software design philosophy that separates concerns into distinct layers:

• Presentation Layer: UI components (Activities, Fragments, ViewModels)
• Domain Layer: Business logic and use cases
• Data Layer: Repositories, data sources, and models

Why Use Clean Architecture?

1. Testability: Each layer can be tested independently
2. Maintainability: Changes in one layer don't affect others
3. Scalability: Easy to add new features without breaking existing code

Implementation Example

// Domain Layer - Use Case
class GetUserProfileUseCase(
    private val userRepository: UserRepository
) {
    suspend operator fun invoke(userId: String): Result<UserProfile> {
        return userRepository.getUserProfile(userId)
    }
}

// Presentation Layer - ViewModel
class ProfileViewModel(
    private val getUserProfile: GetUserProfileUseCase
) : ViewModel() {
    
    private val _uiState = MutableStateFlow<UiState>(UiState.Loading)
    val uiState: StateFlow<UiState> = _uiState.asStateFlow()
    
    fun loadProfile(userId: String) {
        viewModelScope.launch {
            getUserProfile(userId).fold(
                onSuccess = { profile ->
                    _uiState.value = UiState.Success(profile)
                },
                onFailure = { error ->
                    _uiState.value = UiState.Error(error.message)
                }
            )
        }
    }
}

Key Takeaways

• Keep your layers independent
• Use dependency injection (Hilt/Dagger)
• Write tests for each layer
• Follow SOLID principles

Clean Architecture might seem complex at first, but the long-term benefits are worth the initial investment.