android_xml_mvvm_arch.kt

class UserViewModel(private val getUsersUseCase: GetUsersUseCase) : ViewModel() {
    private val _uiState = MutableStateFlow<UiState>(UiState.Loading)
    val uiState: StateFlow<UiState> = _uiState.asStateFlow()

    init {
        loadUsers()
    }

    fun loadUsers() {
        viewModelScope.launch {
            getUsersUseCase().collect { result ->
                _uiState.value = when (result) {
                    is Result.Loading -> UiState.Loading
                    is Result.Success -> UiState.Success(result.data)
                    is Result.Error -> UiState.Error(result.message)
                }
            }
        }
    }
}

// UserListScreen.kt
@Composable
fun UserListScreen(viewModel: UserViewModel = viewModel()) {
    val uiState by viewModel.uiState.collectAsState()
    when (val state = uiState) {
        is UiState.Loading -> LoadingIndicator()
        is UiState.Success -> {
            LazyColumn {
                items(state.users) { user ->
                    UserItem(user)
                }
            }
        }

        is UiState.Error -> ErrorMessage(state.message)
    }
}