Android ViewModel & State Management

Instructions

Use ViewModel to hold state and business logic. It must outlive configuration changes.

1. UI State (StateFlow)

• What: Represents the persistent state of the UI (e.g., Loading, Success(data), Error).
• Type: StateFlow<UiState>.
• Initialization: Must have an initial value.
• Exposure: Expose as a read-only StateFlow backing a private MutableStateFlow.

  private val _uiState = MutableStateFlow<UiState>(UiState.Loading)
  val uiState: StateFlow<UiState> = _uiState.asStateFlow()
  

• Updates: Update state using .update { oldState -> ... } for thread safety.