MutableLiveData不会触发loadAfter使用PagedList从Android ROM获取数据

一些可能的原因 loadAfter 未触发:

Solution 1 :呼叫 getItem 里面 onBindViewHolder

Solution 2 submitList 到 PagedListAdapter

Solution 3 ListAdapter 具有 页面适配器

DataBinding 一切正常,无需寻呼。

我在模仿我的数据源来理解发生了什么。有些函数被挂起,因为它们应该有来自ROM的数据,而ROM需要这些数据。我的代码状态应该是:

适配器

override fun onBindViewHolder(holder: ViewHolder, position: Int) {
    getItem(position).let { wkda ->
        with(holder) {
            wkda?.apply { bind(createOnClickListener(this)) }
        }
    }
}

vm.manufacturers.observe(viewLifecycleOwner) { manufacturers ->            
            adapter.submitList(manufacturers)
}

视图模型

var manufacturers: MutableLiveData<PagedList<WKDA>> = MutableLiveData()

init {
  viewModelScope.launch {
    repository.getManufacturers(manufacturers)
  }
}

suspend fun getManufacturers(manufacturers: MutableLiveData<PagedList<WKDA>>) {
        withContext(Dispatchers.IO) {
            manufacturers.postValue(ManufacturerPagedList.
                getInstance().
                fetchPage())
        }
}

制造商页面列表

private val executor = ManufacturerExecutor()

private val paginationConfig: PagedList.Config = PagedList.Config.Builder()
        .setPageSize(PAGE_SIZE)
        .setPrefetchDistance(FETCH_DISTANCE)
        .setEnablePlaceholders(false)
        .build()

companion object {
        @Volatile
        private var instance: ManufacturerPagedList? = null
            fun getInstance() = instance ?: synchronized(this) {
                ManufacturerPagedList().also {
                    instance = it
                }
        }
    }

fun fetchPage(): PagedList<WKDA> = PagedList.Builder<Int, WKDA>(
            MockDataSource(),
            paginationConfig)
            .setInitialKey(INITIAL_KEY)
            .setFetchExecutor(executor)
            .setNotifyExecutor(executor)
            .build()
}

数据源

class MockDataSource : PageKeyedDataSource<Int, WKDA>() {
    override fun loadInitial(params: LoadInitialParams<Int>, callback: LoadInitialCallback<Int, WKDA>) {
        callback.onResult(List(20) { generatePost(params.requestedLoadSize) }.toList(), -1, 1)
    }

    override fun loadAfter(params: LoadParams<Int>, callback: LoadCallback<Int, WKDA>) {
        callback.onResult(List(20) { generatePost(params.key) }.toList(), params.key + 1)
    }

    override fun loadBefore(params: LoadParams<Int>, callback: LoadCallback<Int, WKDA>) {
        callback.onResult(List(20) { generatePost(params.key) }.toList(), params.key - 1)
    }

    private fun generatePost(key: Int): WKDA {
        return WKDA("name", "author $key")
    }
}

const val INITIAL_KEY: Int = 0
const val PAGE_SIZE: Int = 15
const val FETCH_DISTANCE: Int = 1

我错过了什么?