Project Setup — Android

This guide walks through the minimal project structure for an Android app using Arkitekt with Jetpack Compose and Hilt.

Project Structure

app/
└── src/main
    ├── java/com/example/myapp
    │   ├── ui
    │   │   ├── main
    │   │   │   └── MainActivity.kt
    │   │   └── home
    │   │       ├── HomeScreen.kt
    │   │       ├── HomeViewModel.kt
    │   │       └── HomeViewState.kt
    │   └── App.kt
    └── res/values/strings.xml

Application Class

Create an Application subclass annotated with @HiltAndroidApp. You can optionally configure global error logging for use cases here.

@HiltAndroidApp
class App : Application() {
    override fun onCreate() {
        super.onCreate()
        UseCaseErrorHandler.globalOnErrorLogger = { error ->
            Log.d("UseCase", "$error")
        }
    }
}

Activity

The main activity serves as the Compose entry point. Annotate it with @AndroidEntryPoint for Hilt injection.

@AndroidEntryPoint
class MainActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            MyAppTheme {
                HomeScreen()
            }
        }
    }
}

ViewState

ViewState holds the UI state as observable Compose mutableStateOf fields. It implements the ViewState interface from the core module.

class HomeViewState @Inject constructor() : ViewState {
    val title = mutableStateOf("")
}

ViewModel

The ViewModel extends BaseCoreViewModel and exposes the view state. Annotate with @HiltViewModel for Hilt injection.

@HiltViewModel
class HomeViewModel @Inject constructor(
    override val viewState: HomeViewState,
) : BaseCoreViewModel<HomeViewState>()

Screen Composable

The screen composable obtains the ViewModel via hiltViewModel() and reads state directly from the view state fields.

@Composable
fun HomeScreen(
    viewModel: HomeViewModel = hiltViewModel(),
) {
    val title by viewModel.viewState.title
    Text(text = title)
}