Android回收器视图最初始终为空

Question

我有一个这样的viewmodel-

private val viewState = SchoolsViewState()

    fun onViewOpened() =
        Transformations.map(schoolUseCase.performAction(SchoolAction.GetList)) {
            when (it) {
                is SchoolResult.Loading -> viewState.copy(loading = true)
                is SchoolResult.ListContent -> viewState.copy(loading = false, listData = it.schoolList)
                is SchoolResult.Error -> viewState.copy(loading = false, error = it.error)
                else -> viewState.copy(loading = false)
            }
        }

viewState类看起来像这样-

data class SchoolsViewState(
    val loading: Boolean = false,
    val schoolList: List<SchoolModel> = emptyList(),
    val error: SchoolResult.ErrorType? = null
)

Fragment视图模型观察代码看起来像这样-

viewModel.onViewOpened().observe(this, Observer {
//Handling the SchoolsViewState here
            swipeContainer.isRefreshing = it.loading

            if (it.schoolList.isNullOrEmpty()) {
                view?.recycler_view?.visibility = View.GONE
                view?.empty_view?.visibility = View.VISIBLE
            } else {
                view?.recycler_view?.visibility = View.VISIBLE
                view?.empty_view?.visibility = View.GONE
                view?.recycler_view?.adapter = schoolAdapter
                myAdapter.setSchoolList(it.schoolList)
            }
        })

问题在于每次刷卡刷新时，我首先会看到空白视图，一旦有数据，便会看到学校列表。因此，这给UI带来了不便。这是由于viewState.copy(...)每次刷新都会为UI提供新状态。我该如何克服这个问题？

Answer 1

view?.recycler_view?.adapter = bookingsAdapter
myAdapter.setSchoolList(it.schoolList)

对我来说这很奇怪

Answer 2

viewModel.onViewOpened().observe(this, Observer {
//Handling the SchoolsViewState here
        swipeContainer.isRefreshing = it.loading

        // if means the loading is finished 
        if (!it.loading) {
            if (it.schoolList.isNullOrEmpty()) {
                view?.recycler_view?.visibility = View.GONE
                view?.empty_view?.visibility = View.VISIBLE
            } else {
                view?.recycler_view?.visibility = View.VISIBLE
                view?.empty_view?.visibility = View.GONE
                view?.recycler_view?.adapter = schoolAdapter
                myAdapter.setSchoolList(it.schoolList)
            }
        } else {
            // here you could show some loading progress or similar
        }
    })