Android Paging3 列表项跳转到屏幕开头并无限循环

Question

我的应用程序中有一个 recyclerview，我想让它与 Android paging3 library.Its 一起工作，但不是我想要的方式。在这里，当我打开列表时，我在 PagingConfig.pageSize 中定义的数据数量在顶部创建。当我继续滚动时，它永远不会像无限循环一样停止。但是当我像这样向下滚动它的工作正常时；

如您所见，向上滚动始终处于启用状态。

我不知道我的代码有什么问题；

我的适配器；

package com.tolgahantutar.bexworkfloww.ui.addressbook

import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.navigation.Navigation
import androidx.paging.PagingDataAdapter
import androidx.recyclerview.widget.DiffUtil
import androidx.recyclerview.widget.RecyclerView
import com.tolgahantutar.bexworkfloww.R
import com.tolgahantutar.bexworkfloww.data.models.userget.UserGetValue
import kotlinx.android.synthetic.main.contacts_layout.view.*

class UserAdapter() :
PagingDataAdapter<UserGetValue, UserAdapter.UserViewHolder>(DiffCallBack()) {

    class DiffCallBack : DiffUtil.ItemCallback<UserGetValue>(){
        override fun areItemsTheSame(oldItem: UserGetValue, newItem: UserGetValue): Boolean {
            return oldItem.name == newItem.name
        }

        override fun areContentsTheSame(oldItem: UserGetValue, newItem: UserGetValue): Boolean {
        return oldItem.name == newItem.name
        }

    }

    override fun onBindViewHolder(holder: UserViewHolder, position: Int) {
        holder.itemView.contac_name_textview.text =getItem(position)!!.name
        holder.itemView.user_profile_text_left_drawable.setText("${(getItem(position)!!.name.substringBefore(" ")).subSequence(0,1)}"+"${(getItem(position)!!.name.substringAfter(" ").subSequence(0,1))}")
        holder.itemView.contact_info_text.text = getItem(position)!!.title
        var getContactValue = getItem(position)!!
        holder.itemView.setOnClickListener {
            val action = AdressBookFragmentDirections.actionUserDetail(getItem(position)!!)
            Navigation.findNavController(it).navigate(action)
        }
    }

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): UserViewHolder {
        return UserViewHolder(
            LayoutInflater.from(parent.context)
                .inflate(R.layout.contacts_layout, parent, false)
        )
    }

    class UserViewHolder(itemView: View): RecyclerView.ViewHolder(itemView) {

    }

}

PagingSource;


import androidx.paging.PagingSource
import com.tolgahantutar.bexworkfloww.data.models.userget.UserGetValue
import com.tolgahantutar.bexworkfloww.data.network.apis.WorkFlowServicesApi

class UserRemotePagingSource(private val api : WorkFlowServicesApi): PagingSource<Int,UserGetValue>(){
    override suspend fun load(params: LoadParams<Int>): LoadResult<Int, UserGetValue> {
        return try {
            val page = params.key?: 1
            val response = api.userGet(2,page,2)
            LoadResult.Page(
                data = response.body()!!.userGetValue,
                prevKey = page-1,
                nextKey = page+1
            )
        }catch (e: Exception){
            LoadResult.Error(e)
        }
    }
}

视图模型；

fun usersPagingFlow(): Flow<PagingData<UserGetValue>>{
        return Pager(
            config = PagingConfig(
                pageSize = 2,
                prefetchDistance = 2,
                enablePlaceholders = true,
                initialLoadSize = 2*3
            )
        ){
            UserRemotePagingSource(api)
        }.flow
    }

和片段；

recycler_view_contacts.setHasFixedSize(true)
            recycler_view_contacts.adapter = pagingDataAdapter
        recycler_view_contacts.layoutManager = LinearLayoutManager(requireContext())

            lifecycleScope.launch {
                addressBookViewModel.usersPagingFlow().collectLatest { pagingData ->
                    pagingDataAdapter.submitData(pagingData)
                }
            }

Answer 1

在您的 PagingSource 实现中，您似乎需要检查您的键何时为 1，然后将 prevKey 设置为 null 以标记列表的结尾。

当你给你的 api 一个负数时，它看起来像是发生了什么，它只是再次加载第一页。

Android Paging3 列表项跳转到屏幕开头并无限循环

Android Paging3 list items jumps to beginning of the screen and infinite loop

android

android-recyclerview

android-paging