👀 Views: 65 💬 Answers: 1 📅 Created: 2025-06-05

android recyclerview paging3 kotlin-coroutines stateflow Kotlin

I've been researching this but This might be a silly question, but I've been struggling with this for a few days now and could really use some help... I'm stuck on something that should probably be simple. I'm experiencing unexpected behavior with my RecyclerView that uses Paging 3 combined with Kotlin Flows and StateFlows. I have a setup where I'm trying to load paged data from a Room database and display it in a RecyclerView, but I'm noticing that the loading state isn't managed properly, resulting in a brief flash of an empty state before the data appears. Here's a simplified version of my ViewModel code: ```kotlin class MyViewModel(private val repository: MyRepository) : ViewModel() { val pagedData: Flow<PagingData<MyData>> = repository.getPagedData().cachedIn(viewModelScope) val loadingState: StateFlow<Boolean> = MutableStateFlow(true) init { viewModelScope.launch { pagedData.collectLatest { data -> loadingState.value = false } } } } ``` And in my Fragment, I observe the loading state and submit the paged data to the adapter: ```kotlin class MyFragment : Fragment() { private lateinit var viewModel: MyViewModel private lateinit var adapter: MyAdapter override fun onViewCreated(view: View, savedInstanceState: Bundle?) { super.onViewCreated(view, savedInstanceState) viewModel = ViewModelProvider(this).get(MyViewModel::class.java) adapter = MyAdapter() recyclerView.adapter = adapter lifecycleScope.launchWhenStarted { viewModel.loadingState.collect { isLoading -> progressBar.isVisible = isLoading } } lifecycleScope.launchWhenStarted { viewModel.pagedData.collect { data -> adapter.submitData(data) } } } } ``` I'm using the latest version of Paging 3 and Kotlin Coroutines. The issue seems to be that during the initial load, the `loadingState` is set to `false` as soon as `collectLatest` receives any data, but the adapter might not have finished submitting the data yet. This results in a flicker where the RecyclerView is empty briefly before displaying the items. I've tried delaying the setting of `loadingState` to `false` until after the adapter has submitted the data, but I cannot find a reliable way to synchronize this. Is there a recommended approach for managing loading states in this kind of setup? Am I missing something in the flow of data that could help prevent this flicker? Is there a better approach? For context: I'm using Kotlin on Linux. This is part of a larger service I'm building. Am I missing something obvious? This is for a web app running on macOS. What am I doing wrong?