main adapter not submitting paging data android kotlin - android-studio

Question

Main Fragment:
here were initializing the recyclerview and the viewmodel and getting the data to submit to the adapter:
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
// Inflate the layout for this fragment
val binding: FragmentMainBinding = FragmentMainBinding.inflate(inflater, container, false)
this.binding = FragmentMainBinding.inflate(layoutInflater)
dataFromViewModel = arrayListOf()
setupViewModel()
setupList()
setupView()
return binding.root;
}
private fun setupView() {
viewLifecycleOwner.lifecycleScope.launchWhenCreated {
viewModel.listData.collectLatest {
Log.e("Output Frg", it.toString())
if (!dataFromViewModel.contains(it)) {
dataFromViewModel.add(it)
mainAdapter.submitData(it)
mainAdapter.notifyDataSetChanged()
Log.e(TAG, "setupView: ${mainAdapter.repos.toString()}", )
}
}
}
}
private fun setupList() {
mainAdapter = MainAdapter()
val gridLayoutManager: GridLayoutManager = GridLayoutManager(context, 2)
binding.recyclerview.apply {
layoutManager = gridLayoutManager
adapter = mainAdapter
}
// mainAdapter.addLoadStateListener { loadState ->
//
// if (loadState.refresh is LoadState.Loading && !flag) {
// binding.progressbar.visibility = View.VISIBLE
// flag = true
// } else {
// binding.progressbar.visibility = View.GONE
// }
// }
}
private fun setupViewModel() {
viewModel =
ViewModelProvider(
this,
ViewModelFactory(RetrofitService.getApiService())
)[MainViewModel::class.java]
}
Main ViewModel:
here were just calling the postdatasource function and adding it to the listData value
class MainViewModel(private val apiService: RetrofitService) : ViewModel() {
val listData = Pager(PagingConfig(pageSize = 6)) {
PostDataSource(apiService)
}.flow.cachedIn(viewModelScope)
}
PostDataSource:
Here, we have extended PostDataSource with PagingSource which will implement a suspend load function which will help us to load the data.
PostDataSource also takes a primary constructor parameter APIService. PostDataSource acts here as a repository and the load function gets the data from the API.
Since the load function is a suspend function, we can call other suspend functions inside it without any issues which we created in APIService.
In the PostDataSource, we take two parameters one of integer type and other of the data type we have to load on the list item. The integer parameter represents the page number here.
Here, we get the page number from params and assign it to nextPage variable using param.key and if it returns null, we set a default value 1.
We also do the API call and get assign the response to the response variable using APIService which we passed as a constructor parameter to PostDataSource class.
After doing all the operations with the successful response, we return the LoadResult.Page object here with the required data and it something went wrong we use LoadResult.Error.
We are also passing null as the next key if there is no corresponding data in that direction.
class PostDataSource(private val apiService: RetrofitService) : PagingSource<Int, repo>() {
override suspend fun load(params: LoadParams<Int>): LoadResult<Int, repo> {
try {
val currentLoadingPageKey = params.key ?: 1
val response = apiService.getListData(currentLoadingPageKey)
val responseData = mutableListOf<repo>()
var repos : List<repo>
val data = response
responseData.addAll(data)
Log.e(TAG, "load: $responseData", )
val prevKey = if (currentLoadingPageKey == 1) null else currentLoadingPageKey - 1
return LoadResult.Page(
data = responseData,
prevKey = prevKey,
nextKey = currentLoadingPageKey.plus(1)
)
} catch (e: Exception) {
return LoadResult.Error(e)
}
}
override fun getRefreshKey(state: PagingState<Int, repo>): Int? {
return state.anchorPosition?.let { anchorPosition ->
val anchorPage = state.closestPageToPosition(anchorPosition)
anchorPage?.prevKey?.plus(1) ?: anchorPage?.nextKey?.minus(1)
}
}
// fun getAllrepos() = retrofitService.getAllrepos()
}
MainAdapter:
Now, we will update the MainListAdapter. We will extend the MainListAdapter with PagingDataAdapter and the PagingDataAdapter will take the type of data we need to display in the list and the ViewHolder.
It also takes a DiffUtil callback, as a parameter to its primary constructor which helps the PagingDataAdapter to update the items if they are changed or updated. And DiffUtil callback is used because they are more performant.
Now, the MainListAdapter looks like,
class MainAdapter : PagingDataAdapter<repo, MainAdapter.ViewHolder>(DiffCallBack) , Filterable {
private lateinit var Repos : List<repo>
class ViewHolder(view: View, mlistener: onItemClickListener) : RecyclerView.ViewHolder(view)
private lateinit var mlistener: onItemClickListener
interface onItemClickListener {
fun OnItemClick(position: Int)
}
var repos: MutableList<repo> = ArrayList()
private var reposFull: MutableList<repo> = ArrayList()
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
holder.itemView.findViewById<TextView>(R.id.title).text = getItem(position)?.name
Log.e(TAG,"name ${holder.itemView.findViewById<TextView>(R.id.title).text}", )
Glide.with(holder.itemView.context)
.load(getItem(position)?.owner?.avatar_url)
.into(holder.itemView.findViewById(R.id.imgCircle))
// val repo = repos[position]
//
//
// val mainViewHolder: ViewHolder = holder as ViewHolder
// mainViewHolder.itemView Title?.text = repo.name
// mainViewHolder.Image?.let {
// Glide.with(holder.itemView.context).load(repo.owner.avatar_url).into(
// it
// )
// }
}
fun submitList(list: PagingData<repo>) {
Repos = list as List<repo>
notifyDataSetChanged()
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
return ViewHolder(
LayoutInflater
.from(parent.context)
.inflate(R.layout.repo_layout, parent, false), mlistener
)
}
fun setOnItemClickListener(listener: onItemClickListener) {
mlistener = listener
}
object DiffCallBack : DiffUtil.ItemCallback<repo>() {
override fun areItemsTheSame(oldItem: repo, newItem: repo): Boolean {
return oldItem.id == newItem.id
}
override fun areContentsTheSame(oldItem: repo, newItem: repo): Boolean {
return oldItem == newItem
}
}
// class MainViewHolder(itemView: View, listener: onItemClickListener) : RecyclerView.ViewHolder(itemView) {
// var Title: TextView? =
// itemView.findViewById<View>(com.lau.google_rep.R.id.title) as TextView
// var Image: ImageView? =
// itemView.findViewById<View>(com.lau.google_rep.R.id.imgCircle) as ImageView
//
// init {
// itemView.setOnClickListener {
// listener.OnItemClick(adapterPosition)
// }
// }
// }
override fun getFilter(): Filter {
return exampleFilter
}
private val exampleFilter: Filter = object : Filter() {
override fun performFiltering(constraint: CharSequence?): FilterResults? {
val filteredList: MutableList<repo> = ArrayList()
if (constraint == null || constraint.length == 0) {
filteredList.addAll(reposFull)
} else {
val filterPattern = constraint.toString().toLowerCase().trim { it <= ' ' }
for (item in reposFull) {
if (item.name.toLowerCase().contains(filterPattern)) {
filteredList.add(item)
}
}
}
Log.d(TAG, "publishResults: $filteredList")
val results = FilterResults()
results.values = filteredList
return results
}
#SuppressLint("NotifyDataSetChanged")
override fun publishResults(constraint: CharSequence?, results: FilterResults) {
repos.clear()
(results.values as? Collection<repo>)?.let { repos.addAll(it) }
notifyDataSetChanged()
}
}
}
retrofit service:
interface RetrofitService {
// #Headers("Authorization: token ")
#GET("repos")
suspend fun getListData(#Query("page") pageNumber: Int): List<repo>
companion object{
private val moshi = Moshi.Builder()
.add(KotlinJsonAdapterFactory())
.build()
fun getApiService() = Retrofit.Builder()
.baseUrl("https://api.github.com/orgs/google/")
.addConverterFactory(MoshiConverterFactory.create(moshi))
.build()
.create(RetrofitService::class.java)
}
}