android kotlin`何时``satement''not smartcasting

Question

和我的MainViewModel

 private val _mainState = MutableStateFlow(MainState.Loading)
    val mainState = _mainState.asStateFlow()
        .onStart {
            if(!hasCompleted) {
                getLoginCredentials()
                hasCompleted = true
            }

thin在我的综合

中

 val mainState by mainViewModel.mainState.collectAsStateWithLifecycle(initialValue = MainState.Loading)
       
        when(val status = mainState) {
           MainState.Loading -> {
                Box(
                    modifier = Modifier.fillMaxSize(),
                    contentAlignment = Alignment.Center
                ) {
                    CircularProgressIndicator()
                }
            }
            is MainState.Success -> {
                NavHost(
                    navController = navController,
                    startDestination = if(status.isSessionActive) Route.DashboardGraph else Route.AuthenticationGraph
                ) {

                    this.authentication(navController)

                    this.dashboardGraph(navController)

                    this.settingsGraph(navController)
                }
            }
        }
            }

我在此行中遇到以下错误

is MainState.Success -> {

这是错误

Incompatible types: MainState. Success and MainState. Loading

替换：

private val _mainState = MutableStateFlow(MainState.Loading)

Answer 1

：

private val _mainState: MutableStateFlow<MainState> = MutableStateFlow(MainState.Loading) 或：

private val _mainState = MutableStateFlow<MainState>(MainState.Loading)