When developing Android apps using Kotlin and Jetpack Compose, the architecture you choose should align with your application's needs, scalability, and maintainability. Let's explore the best architecture and discuss other alternatives with examples to help you make the best decision.
1. MVVM (Model-View-ViewModel) Architecture
Overview:
MVVM is the most commonly recommended architecture for Android apps using Jetpack Compose. It works seamlessly with Compose’s declarative UI structure and supports unidirectional data flow.
- Model: Represents the data and business logic (e.g., network requests, database calls, etc.).
- View: Composed of composable functions in Jetpack Compose. It displays the UI and reacts to state changes.
- ViewModel: Holds UI-related state and business logic. It is lifecycle-aware and acts as a bridge between the View and Model.
How MVVM Works:
- The View is responsible for presenting data using Compose. It observes the state exposed by the ViewModel via
StateFloworLiveData. - The ViewModel holds and processes the data and updates the state in response to user actions or external data changes.
- The Model handles data fetching and business logic and communicates with repositories or data sources.
Benefits:
- Separation of concerns: The View and Model are decoupled, making the app easier to maintain.
- Reactivity: With Compose's state-driven UI, the View updates automatically when data changes in the ViewModel.
- Scalability: MVVM works well for larger, complex apps.
Example:
// ViewModel
class MyViewModel : ViewModel() {
private val _state = MutableStateFlow(MyState())
val state: StateFlow<MyState> get() = _state
fun fetchData() {
// Simulate network request
_state.value = _state.value.copy(data = "Fetched Data")
}
}
// Composable View
@Composable
fun MyScreen(viewModel: MyViewModel = viewModel()) {
val state by viewModel.state.collectAsState()
Column {
Text(text = state.data)
Button(onClick = { viewModel.fetchData() }) {
Text("Fetch Data")
}
}
}
Best For:
- Real-time applications (e.g., chat apps, social media, etc.)
- Apps with dynamic and complex UI requiring frequent backend updates.
- Enterprise-level applications where clear separation of concerns and scalability are required.
2. MVI (Model-View-Intent) Architecture
Overview:
MVI focuses on unidirectional data flow and immutable state. It's more reactive than MVVM and ensures that the View always displays the latest state.
- Model: Represents the application’s state, typically immutable.
- View: Displays the UI and reacts to state changes.
- Intent: Represents the actions that the View triggers (e.g., button clicks, user input).
How MVI Works:
- The View sends Intents (user actions) to the Presenter (or ViewModel).
- The Presenter updates the Model (state) based on these actions and then triggers a state change.
- The View observes the state and re-renders itself accordingly.
Benefits:
- Unidirectional data flow: The state is always predictable as changes propagate in one direction.
- Immutable state: Reduces bugs associated with mutable state and ensures UI consistency.
- Reactive: Well-suited for applications with frequent UI updates based on state changes.
Example:
// MVI - State, ViewModel
data class MyState(val data: String = "")
class MyViewModel : ViewModel() {
private val _state = MutableStateFlow(MyState())
val state: StateFlow<MyState> get() = _state
fun processIntent(intent: MyIntent) {
when (intent) {
is MyIntent.FetchData -> {
_state.value = MyState("Fetched Data")
}
}
}
}
// Composable View
@Composable
fun MyScreen(viewModel: MyViewModel = viewModel()) {
val state by viewModel.state.collectAsState()
Column {
Text(text = state.data)
Button(onClick = { viewModel.processIntent(MyIntent.FetchData) }) {
Text("Fetch Data")
}
}
}
Best For:
- Complex UI interactions: Apps with multiple states and actions that must be tightly controlled.
- Real-time data-driven apps where state changes must be captured and handled immutably.
- Apps that require a highly reactive UI, such as games or media streaming apps.
3. MVP (Model-View-Presenter) Architecture
Overview:
MVP is a simpler architecture often used in legacy apps. In MVP, the Presenter controls the logic and updates the View, which is passive and only responsible for displaying data.
- Model: Represents the data and business logic.
- View: Displays UI and delegates user interactions to the Presenter.
- Presenter: Acts as a middleman, processing user input and updating the View.
How MVP Works:
- The View delegates all user actions (clicks, input, etc.) to the Presenter.
- The Presenter fetches data from the Model and updates the View accordingly.
Benefits:
- Simple and easy to implement for small applications.
- Decouples UI logic from the data layer.
Example:
// MVP - Presenter
interface MyView {
fun showData(data: String)
}
class MyPresenter(private val view: MyView) {
fun fetchData() {
// Simulate fetching data
view.showData("Fetched Data")
}
}
// Composable View
@Composable
fun MyScreen(view: MyView) {
val presenter = remember { MyPresenter(view) }
Column {
Button(onClick = { presenter.fetchData() }) {
Text("Fetch Data")
}
}
}
class MyViewImpl : MyView {
override fun showData(data: String) {
println("Data: $data")
}
}
Best For:
- Simple apps with minimal business logic.
- Legacy projects that already follow the MVP pattern.
- Applications with simple user interactions that don’t require complex state management.
Conclusion: Which Architecture to Choose?
| Architecture | Strengths | Best For | Example Use Cases |
|---|---|---|---|
| MVVM | Seamless integration with Jetpack ComposeClear separation of concernsScalable and testable | Large, complex appsReal-time appsTeam-based projects | E-commerce apps, banking apps, social apps |
| MVI | Immutable stateUnidirectional data flowReactive UI | Highly interactive appsReal-time dataComplex state management | Messaging apps, live score apps, media apps |
| MVP | Simple to implementGood for small appsEasy to test | Small appsLegacy appsSimple UI interactions | Note-taking apps, simple tools, legacy apps |
Best Recommendation:
- MVVM is generally the best architecture for most Android Kotlin Compose apps due to its scalability, maintainability, and seamless integration with Compose.
- MVI is ideal for apps that require complex state management and reactive UI updates.
- MVP is still useful for simple apps or projects that already follow MVP.
Thanks for reading! 🎉 I'd love to know what you think about the article. Did it resonate with you? 💭 Any suggestions for improvement? I’m always open to hearing your feedback to improve my posts! 👇🚀. Happy coding! 💻✨
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