android-state

Android State Management

Priority: P0 (CRITICAL)

1. Structure ViewModel

• Expose ONE StateFlow<UiState> via .asStateFlow().
• Use viewModelScope for all coroutines.
• Trigger initial load in init block.

See templates for ViewModel and UiState examples.

2. Define UI State (LCE Pattern)

• Use sealed interface with Loading, Content, Error variants.
• Mark data classes @Immutable.

See templates for sealed UiState pattern.

3. Collect State Lifecycle-Safely

• Use collectAsStateWithLifecycle() in Compose.
• Use SharingStarted.WhileSubscribed(5000) for shared resources.

Anti-Patterns

• No LiveData for New Code: Use StateFlow — lifecycle-safe and Compose-compatible.
• No Public MutableStateFlow: Expose only .asStateFlow() to consumers.
• No Context in ViewModel: Leaks Activity. Use Application context if truly needed.

Verification

• Each ViewModel exposes exactly one StateFlow<UiState>.
• UiState is a sealed interface with Loading, Content, Error variants.
• UI collects with collectAsStateWithLifecycle().
• ./gradlew test passes for ViewModel tests.

References

• Templates