每当 StateFlow 更新和发出数据时，ListAdapter 都不会收到通知

Question

StateFlow 在更改后发出新数据，但 ListAdapter 不是 updated/notified，但是当配置更改时（即设备从纵向模式旋转到横向模式）更新是发生：

class TutorialListFragment : Fragment() {
    
        private lateinit var binding: FragmentTutorialListBinding
    
        private val viewModel: ITutorialViewModel by viewModels<TutorialViewModelImpl>()
        private lateinit var adapter: TutorialAdapter
        override fun onCreateView(
            inflater: LayoutInflater, container: ViewGroup?,
            savedInstanceState: Bundle?
        ): View {
    
            binding = FragmentTutorialListBinding.inflate(inflater, container, false)
            return binding.root
    
        }
    
        override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
            super.onViewCreated(view, savedInstanceState)
    
            val recyclerView = binding.recyclerView
    
            adapter = TutorialAdapter()
            recyclerView.adapter = adapter    
     
            loadData()   
    
        }
    
        private fun loadData() {
            viewModel
                .getTutorialList()
    
            val tutorialList: MutableList<TutorialResponse> = mutableListOf()

            viewModel
                .tutorialListStateFlow
                .onEach { list ->
                    list.forEach {tutorialResponse->
                        tutorialList.add(tutorialResponse)                       
                        Log.e("TUTORIAL_LIST_FRAG", "$tutorialResponse")
                    }
                    adapter.submitList(tutorialList)
                }.launchIn(viewLifecycleOwner.lifecycleScope)
        }
}

视图模型是：

class TutorialViewModelImpl: ViewModel(), ITutorialViewModel {

    private val mTutorialRepository: ITutorialRepository = TutorialRepositoryImpl()

    private val _tutorialListStateFlow = MutableStateFlow<List<TutorialResponse>>(mutableListOf())
    override val tutorialListStateFlow: StateFlow<List<TutorialResponse>>
        get() = _tutorialListStateFlow.asStateFlow()

    init {
        mTutorialRepository
            .getTutorialListSuccessListener {
                viewModelScope
                    .launch {
                        _tutorialListStateFlow.emit(it)
                        Log.e("TUTORIAL_GL_VM", "$it")
                    }
            }    
       
    }

    override fun getTutorialList() {
        // Get list
        mTutorialRepository.getTutorialList()
    }
}

当我查看 Logcat 时，我看到了这一行：

Log.e("TUTORIAL_GL_VM", "$it")

打印所有更改，但 ListAdapter 中没有更新。

Answer 1

我假设你来自 mTutorialRepository 的数据不是一个流，所以你必须添加 .toList() 如果你想在 stateFlow 中发出列表以获得通知


mTutorialRepository.getTutorialListSuccessListener {
   viewModelScope.launch {
      // here add .toList()
      _tutorialListStateFlow.emit(it.toList())             
   }
}

或者如果它仍然不起作用，请尝试像这样更改您的 loadData()


private fun loadData() {
// idk what are doing with this ??
viewModel.getTutorialList()

lifecycleScope.launch {
     viewModel.tutorialListStateFlow.collect { list ->
       adapter.submitList(list)
    }
  }
}

每当 StateFlow 更新和发出数据时，ListAdapter 都不会收到通知

ListAdapter is not being notified whenever data is updated and emitted by StateFlow

android

kotlin

kotlin-coroutines

kotlin-stateflow