Android Kotlin Patterns

Android Kotlin Patterns

Production Android development with Kotlin and Jetpack.

Architecture (Modern Android Dev)

Recommended Stack

• UI: Jetpack Compose with Material 3
• State: ViewModel + StateFlow
• DI: Hilt/Dagger
• DB: Room
• Network: Retrofit + OkHttp
• Async: Coroutines + Flow
• Navigation: Compose Navigation

Project Structure

app/
├── data/
│   ├── local/ (Room DAOs, entities)
│   ├── remote/ (Retrofit APIs, DTOs)
│   └── repository/
├── domain/
│   ├── model/
│   └── usecase/
├── ui/
│   ├── components/
│   ├── screens/
│   └── theme/
└── di/ (Hilt modules)

Jetpack Compose Patterns

State Hoisting

// State flows down, events flow up
@Composable
fun CounterScreen(viewModel: CounterViewModel = hiltViewModel()) {
    val state by viewModel.state.collectAsStateWithLifecycle()
    CounterContent(
        count = state.count,
        onIncrement = viewModel::increment
    )
}

Performance

• Use remember and derivedStateOf for computations
• LazyColumn for lists, not Column with scrolling
• Stable types via @Immutable/@Stable annotations

Play Store Submission

• [ ] Privacy Policy URL set
• [ ] App signing key backed up
• [ ] In-app reviews integrated
• [ ] Crash reporting (Firebase)
• [ ] proguard-rules.pro configured
• [ ] App bundles (.aab) for distribution