👀 Views: 11 💬 Answers: 1 📅 Created: 2025-06-13

kotlin android coroutines viewmodel stateflow Kotlin

Hey everyone, I'm running into an issue that's driving me crazy. I'm optimizing some code but I've looked through the documentation and I'm still confused about I'm facing an issue where my `MutableStateFlow` in a `ViewModel` does not update its state as expected when the fragment is recreated, particularly after a configuration change..... I'm using Kotlin Coroutines and the `viewModelScope` to launch my coroutine. Here’s the relevant code snippet from my ViewModel: ```kotlin class MyViewModel : ViewModel() { private val _data = MutableStateFlow<String?>(null) val data: StateFlow<String?> get() = _data fun fetchData() { viewModelScope.launch { // Simulating a network call delay(1000) _data.value = "Fetched Data" } } } ``` In my fragment, I'm observing the `data` flow: ```kotlin class MyFragment : Fragment() { private val viewModel: MyViewModel by viewModels() override fun onViewCreated(view: View, savedInstanceState: Bundle?) { super.onViewCreated(view, savedInstanceState) lifecycleScope.launchWhenStarted { viewModel.data.collect { value -> // Update UI textView.text = value ?: "Loading..." } } viewModel.fetchData() } } ``` The issue arises when I rotate my device or trigger a configuration change. After the fragment is recreated, I expect to see the updated value in `textView`, but it remains "Loading...". I've checked that `fetchData()` is indeed called again, and I'm also sure the coroutine is running. However, it seems like the original state is retained instead of the updated one. I’ve tried using `reset()` on the `StateFlow` in `onCleared()` but it doesn’t seem to help. Am I missing something fundamental with how `MutableStateFlow` works in conjunction with ViewModel lifecycle? Any insights on how to ensure that the state updates correctly after a configuration change would be greatly appreciated. I'm working on a service that needs to handle this. Thanks in advance! Thanks in advance! For context: I'm using Kotlin on Linux.