Building Better Android Apps with MVVM and Clean Architecture

Nov 11, 2025 |

21 minutes read

Why MVVM and Clean Architecture Are Essential for Scalable Android Apps

Are you struggling with maintaining your Android codebase as it grows? Does adding new features feel like navigating a maze of tangled dependencies? Clean Architecture combined with MVVM (Model-View-ViewModel) is your solution to building scalable, testable, and maintainable Android applications that can grow without becoming unmanageable.

Understanding the Problem

Many Android developers start with simple MVVM architecture, which works perfectly for small projects. However, as your app grows, ViewModels become bloated with multiple responsibilities, making code maintenance increasingly difficult. You’ll notice your ViewModels handling database operations, network calls, business logic, and UI state management all at once.

This is exactly where Clean Architecture proves its value.

What does Clean Architecture mean?

Clean Architecture outlines a set of principles focused on separating concerns and managing dependencies effectively. Its core idea is straightforward but powerful – the inner layers must remain independent of the outer layers, ensuring a flexible and maintainable system where modifications in one layer don’t affect others.

Think of it like building a house with independent rooms – you can renovate the kitchen without affecting the bedroom.

Why Combine MVVM with Clean Architecture?

MVVM excels at separating UI from business logic, giving you the advantage of Android’s built-in ViewModel class and lifecycle awareness. Clean Architecture takes this separation several steps further by organizing your entire codebase into distinct layers with clear responsibilities.

This combination delivers the best of both worlds: Android’s native ViewModel support with Clean Architecture’s enterprise-grade scalability.

Key Benefits You’ll Get

Superior Testability – Each layer can be tested independently without Android framework dependencies or actual network calls, making your tests fast and reliable.

Enhanced Maintainability – Clear separation of concerns makes it easy to locate and modify code without accidentally breaking unrelated features.

Natural Scalability – Adding new features becomes straightforward as the architecture naturally accommodates growth without requiring major refactoring.

Improved Team Collaboration – Multiple developers can work on separate layers at the same time without interfering with one another’s work.

Business Logic Portability – Your core business logic becomes completely independent of Android, making it potentially reusable across platforms.

The Three-Layer Architecture Explained

Clean Architecture with MVVM divides your application into three main layers, each with crystal-clear responsibilities.

User Interface or Presentation Layer

This layer encompasses everything the user sees and interacts with, including Activities, Fragments, Composable functions, and ViewModels. The key principle is to keep UI components simple, focusing solely on visual presentation and user interface logic.

Key Components:

Activities and Fragments – Display data to users and capture input, but should contain minimal logic.

Modern declarative UI components (Jetpack Compose Screens ) that automatically adjust based on state changes.

ViewModels – Act as the bridge between your UI and business logic, managing UI state and surviving configuration changes.

UI State Classes – Represent different states of your interface like Loading, Success, Error, and Empty.

The ViewModel observes data from the domain layer and transforms it into formats that are easy for your UI to consume. It should never contain business logic – that’s the domain layer’s job.

Core Business Logic Layer

This layer represents the core of your application. It holds all the business logic and remains entirely independent of any frameworks or external dependencies. It consists purely of Kotlin code, with no Android-specific imports.

Key Components:

Use Cases (Interactors) – Single-responsibility classes that execute specific business actions. Each Use Case does exactly one thing and does it well.

Domain Models – Plain Kotlin data classes representing your application’s core business entities.

Repository Interfaces – Contracts that define how data should be accessed, without specifying implementation details.

For example, you might have Use Cases like GetUserProfileUseCase, UpdateUserSettingsUseCase, or SubmitOrderUseCase. Each performs one specific action, making your code highly reusable and incredibly easy to test.

The beauty of Use Cases is that they act as mediators between ViewModels and Repositories, abstracting business logic and allowing reuse wherever that business action is needed.

Data or Repository Layer

This layer fulfills the repository interfaces defined in the domain layer and manages all data-related operations. Whether the data originates from Room databases, Retrofit APIs, SharedPreferences, or external services, this layer is responsible for handling it seamlessly.

Key Components:

Repository Implementations – Concrete classes that fulfill the contracts defined in domain layer repository interfaces.

Data Sources – Split into remote (API clients using Retrofit) and local (Room database, SharedPreferences) data providers.

Data Transfer Objects (DTOs) – Classes representing API response structures, which often differ from your domain models.

Mappers – Functions that convert between DTOs, database entities, and domain models.

The repository serves as the single source of truth, determining whether to retrieve new data from the network or provide cached data from the local database.

Implementing Clean Architecture Step by Step

Step 1: Set up Your Project Dependencies

Add the essential dependencies to your build.gradle file:

Jetpack ViewModel and Lifecycle components
Hilt for dependency injection
Room for local database
Retrofit for networking
Kotlin Coroutines and Flow for asynchronous operations

Step 2: Create the Domain Layer First

Begin by creating your domain models — straightforward data classes that represent your core business entities. For example, in a social media app, these could include models such as User, Post, or Comment.

Next, create repository interfaces with suspend functions that define data contracts:

kotlin


interface UserRepository {
    suspend fun getProfile(userId: String): Result
    suspend fun updateProfile(user: User): Result
    fun observeUser(userId: String): Flow
}

Build your Use Cases as single-responsibility classes. Every Use Case should focus on performing a single business task.

kotlin


class GetUserProfileUseCase(
    private val repository: UserRepository
) {
    suspend fun executeTask(userId: String): Result {
        return repository.loadUserProfile(userId)
    }
}

Step 3: Implement the Data Layer

Create your local data models and DAOs using Room, which define how data is stored on the device:

kotlin


@Entity(tableName = "users")
data class UserEntity(
    @PrimaryKey val id: String,
    val name: String,
    val email: String
)

Next, set up your Retrofit API interface to handle remote data operations:
kotlin
interface ApiService {
    @GET("users/{id}")
    suspend fun getUser(@Path("id") userId: String): UserDto
}

Implement your repositories by coordinating between local and remote data sources:
kotlin
class UserRepositoryImpl(
    private val apiService: ApiService,
    private val userDao: UserDao
) : UserRepository {
    override suspend fun getProfile(userId: String): Result {
        return catching {
            val userDto = apiService.getUser(userId)
            val user = userDto.toDomainModel()
            userDao.insert(user.toEntity())
            Result.catching { user }
        } catch (e: Exception) {
            Result.failure(e)
        }
    }
}

Create mapper functions to convert between different data representations:

kotlin


fun UserDto.toDomainModel() = User(
    id = this.userId,
    name = this.fullName,
    email = this.emailAddress
)

fun UserEntity.toDomainModel() = User(
    id = this.id,
    name = this.name,
    email = this.email
)

Step 4: Build the Presentation Layer

Set up Hilt for dependency injection by annotating your Application class with @HiltAndroidApp.

Create ViewModels that inject Use Cases and manage UI state:

kotlin


@HiltViewModel
class ProfileViewModel @Inject constructor(
    private val getUserProfileUseCase: GetUserProfileUseCase
) : ViewModel() {
    
    private val _viewState = MutableStateFlow(UiState.Loading)
   val uiStateFlow: StateFlow = _uiState.stateIn(viewModelScope)
    
    fun loadProfile(userId: String) {
        viewModelScope.launch {
            _uiState.value = UiState.Loading
            getUserProfileUseCase(userId)
                .onSuccess { user ->
                    _uiState.value = UiState.Success(user)
                }
                .onFailure { error ->
                    _uiState.value = UiState.Error(error.message)
                }
        }
    }
}

Keep your Activities and Fragments minimal, only observing ViewModel state and rendering UI:

kotlin


@AndroidEntryPoint
class ProfileActivity : AppCompatActivity() {
    private val viewModel: ProfileViewModel by viewModels()
    
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        
        lifecycleScope.launchWhenCreated {
   		viewModel.uiState.collectLatest { state ->
                when (state) {
                    is UiState.Loading -> showLoading()
                    is UiState.Success -> showProfile(state.user)
                    is UiState.Error -> handleErrorMessage(state.message)
                }
            }
        }
    }
}

Working with Coroutines and Flow

Modern Android development relies heavily on Kotlin Coroutines for asynchronous operations and Flow for reactive data streams.

Define your Use Cases as suspend functions to handle long-running operations without blocking the UI thread. Use coroutines launched from ViewModels via viewModelScope, which automatically cancels when the ViewModel is cleared, helping prevent memory leaks.

Use Room’s Flow support for real-time database updates. When database data changes, your UI updates automatically:

kotlin


@Dao
interface UserDao {
    @Query("SELECT * FROM users WHERE id = :userId")
    fun observeUser(userId: String): Flow
}

Expose UI state through StateFlow in ViewModels, which survives configuration changes and maintains the last emitted state.

Dependency Injection with Hilt

Hilt dramatically simplifies dependency management by generating boilerplate code automatically.

Add the @HiltAndroidApp annotation to your Application class to activate Hilt’s code generation.

Mark Activities, Fragments, and ViewModels with @AndroidEntryPoint and @HiltViewModel to allow automatic dependency injection.

Create Hilt modules to provide dependencies:

kotlin


@Module
@InstallIn(SingletonComponent::class)
object DatabaseModule {
    @Provides
    @Singleton
    fun provideDatabase(@ApplicationContext context: Context): AppDatabase {
        return Room.databaseBuilder(
            context,
            AppDatabase::class.java,
            "app_database"
        ).build()
    }
}

Use @Provides for concrete implementations and @Binds for interface implementations. Specify scopes like @Singleton to control dependency lifecycles.

Error Handling Best Practices

Create a sealed class for representing operation results:

kotlin


sealed class Result {
   data class SuccessData(val content: T) : Result()
   data class ErrorState(val details: String) : Result()
   object Loading : Result()
}

This provides type-safe error handling throughout your application. Repository methods return Result instances, Use Cases propagate them, and ViewModels transform them into UI states.

Always handle errors gracefully with user-friendly messages. Never expose technical error details to end users.

Testing Your Clean Architecture

Clean Architecture makes testing straightforward because each layer is independent.

Unit Test Use Cases with mock repositories to verify business logic without touching databases or networks:

kotlin


@Test
fun `get user profile returns success`() = runTest {
    val mockRepo = mockk()
    coEvery { mockRepo.getUserProfile("123") } returns 
        Result.success(User("123", "John", "john@example.com"))
    
    val useCase = GetUserProfileUseCase(mockRepo)
    val result = useCase("123")
    
    assertTrue(result.isSuccess)
}

Test ViewModels using test coroutine dispatchers and mock Use Cases:

kotlin


@Test
fun `loading profile updates state correctly`() = runTest {
    val mockUseCase = mockk()
    val viewModel = ProfileViewModel(mockUseCase)
    
    // Verify state transitions
    assertEquals(UiState.Loading, viewModel.uiState.value)
}

Test Repositories with fake data sources or in-memory Room databases to verify data handling.

UI Testing with Compose Testing or Espresso to verify correct UI responses.

Common Mistakes to Avoid

Skipping the Domain Layer – Some developers let ViewModels communicate directly with Repositories. This defeats Clean Architecture’s purpose and reduces testability.

Wrong Dependency Direction – Always ensure dependencies point inward. The data layer knows about the domain layer, but the domain layer should never import from the data layer.

Over-Engineering Small Projects – For simple apps with minimal features, standard MVVM might be sufficient. Clean Architecture adds complexity that’s only worthwhile for projects expecting growth.

Creating Too Many Use Cases – Not every repository method needs a separate Use Case. Simple CRUD operations can sometimes be called directly from ViewModels if there’s no business logic involved.

Ignoring Lifecycle – Always collect Flows and observe LiveData in a lifecycle-aware manner to prevent memory leaks.

Performance Considerations

Clean Architecture doesn’t mean sacrificing performance.

Database Optimization – Use Room indices for frequently queried columns. Implement pagination with the Paging 3 library for large datasets. Always run database operations on background dispatchers.

Store API responses in a local database to reduce unnecessary network requests. Implement a retry strategy with progressively increasing delays after each failure, and take advantage of OkHttp’s built-in caching capabilities. Hence, it leads to Network Optimization.

Memory Management – Avoid loading massive datasets into memory simultaneously. Use Kotlin sequences and flows for efficient data processing. Release resources properly in ViewModel’s onCleared() method.

Migration Strategy for Existing Projects

Migrating an existing Android project to Clean Architecture requires careful planning and incremental changes.

Begin with the Domain Layer – Move business logic from ViewModels into Use Cases. This approach delivers instant improvements without the need for a full refactor.

Create Repository Interfaces – Define contracts in the domain layer and gradually move data access code into repository implementations.

Introduce Hilt Gradually – Begin with ViewModels and work your way down to repositories and data sources.

Restructure Package Organization – Once layers are established, reorganize packages to clearly reflect the architecture.

Avoid migrating everything at once. Tackle one feature at a time, refining and improving your approach along the way.

Real-World Project Structure

A production app following Clean Architecture with MVVM typically organizes code like this:

This structure makes it immediately clear where to find specific functionality and where new code should be added.

Practical Tips for Success

Write Tests First – Start with domain layer tests since they’re easiest and provide the most value.

Keep Use Cases Small – Each Use Case should do exactly one thing. If it’s getting complex, split it into multiple Use Cases.

Document Your Architecture – Create a simple diagram showing how layers interact. This helps new team members understand the structure quickly.

Establish Naming Conventions – Consistent naming makes code predictable. For example, always suffix Use Cases with “UseCase” and repositories with “Repository”.

Review Regularly – As your project grows, periodically review whether code is in the correct layer. Architectural violations are easier to fix early.

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The Way Forward

Clean Architecture combined with MVVM provides a robust, professional foundation for building Android applications that can scale from prototype to production. While it requires initial investment in learning and setup, the long-term benefits of maintainability, testability, and team productivity make it worthwhile for any serious Android project.

Architecture isn’t about achieving perfection from day one. It’s about establishing solid patterns that guide your development and continuously improving your codebase. Start small, apply these principles to new features first, and gradually refactor existing code as you gain confidence.

Your future self – and your team members – will thank you for creating an organized, understandable codebase that’s a joy to work with rather than a nightmare to maintain. The initial learning curve is steep, but the destination is worth the journey.

Remember: great architecture isn’t about following rules blindly, it’s about making pragmatic decisions that serve your project’s specific needs while maintaining core principles of separation, testability, and maintainability.