相关疑难解决方法(0)

我有一个登录屏幕，当登录成功并且视图模型更新可变状态变量时，我的期望是调用一个新的可组合函数来显示新屏幕，并删除登录屏幕。问题是，当Screen.AccountsScreen显示新屏幕（又名）时，其内容不断闪烁/重绘，并且登录表单也会发生同样的情况，而该登录表单永远不会被破坏（我知道这一点是因为日志消息“Recomponing...”被无休止地打印） 。我认为发生这种情况是因为isLoginSuccessful状态始终为真。看来我需要一个只能消耗一次的事件，这是正确的吗？如果是这样，我该怎么做？

LoginViewModel.kt

@HiltViewModel
class LoginViewModel @Inject constructor() : ViewModel() {

  var isLoginSuccessful by mutableStateOf(false)
  var errorMessage by mutableStateOf("")
  
  fun onLoginClick(email: String, password:String) {
    errorMessage = ""
    if (credentialsValid(email, password)) {
      isLoginSuccessful = true
    } else {
      errorMessage = "Email or password invalid"
      isLoginSuccessful = false
    }
  }
}

LoginScreen.kt

@Composable
fun loginScreen(
  navController: NavController,
  viewModel: LoginViewModel = hiltViewModel()
) {
  println("Recomponing...")
  // Here gos the code for the login form
  
  if (viewModel.isLoginSuccessful) {
    navController.navigate(Screen.AccountsScreen.route) { …

我正在尝试Navigation使用单个活动和多个Composable屏幕来实现。

这是我的NavHost：

@Composable
@ExperimentalFoundationApi
fun MyNavHost(
    modifier: Modifier = Modifier,
    navController: NavHostController = rememberNavController(),
    startDestination: String = HOME.route,
    viewModelProvider: ViewModelProvider,
    speech: SpeechHelper
) = NavHost(
    modifier = modifier,
    navController = navController,
    startDestination = startDestination
) {
    composable(route = HOME.route) {
        with(viewModelProvider[HomeViewModel::class.java]) {
            HomeScreen(
                speech = speech,
                viewModel = this,
                modifier = Modifier.onKeyEvent { handleKeyEvent(it, this) }
            ) {
                navController.navigateTo(it)
            }
        }
    }

    composable(route = Destination.VOLUME_SETTINGS.route) {
        VolumeSettingsScreen(
            viewModelProvider[VolumeSettingsViewModel::class.java]
        ) { navController.navigateUp() }
    }
} …