i want to add next page (every page is 10) to my recyclerview but it delet my last page - android-recyclerview

Question

my recyclerview fragment:
this is the fragment that I set my recycler view , I want when touch the continue button (btn_continue) add the rest of the list, which is actually the next page, to my list when I click the button
But it deletes the previous list and displays the new list
and i use the kotlin coruotine, viewmodel and recyclerview
class AllUnpublishedAdsFragment : Fragment() {
lateinit var unpublishedAdsAdapter: UnpublishedAdsAdapter
var items = ArrayList<M_Ads>()
lateinit var loadMoreItems: ArrayList<M_Ads>
lateinit var scrollListener: RecyclerViewLoadMoreScroll
lateinit var mLayoutManager: RecyclerView.LayoutManager
val page = "1"
var newpage = page.toInt()
var navController: NavController? = null
lateinit var btn_continue: Button
private lateinit var viewModel: MainViewmodels
lateinit var token: String
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_all_unpublished_ads, container,
false)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
btn_continue = view.findViewById<Button>(R.id.btn_continueAds)
token = arguments?.getString(TOKEN_KEY).toString()
Log.i("TOKEN", token)
setupViewModel(token, page)
continueAds()
unpublishedAdsAdapter.itemClickListener = { item, position ->
val id = item.id
val bundle_id = Bundle()
bundle_id.putString(ID_KEY, id.toString())
navController = Navigation.findNavController(view)
//view.findNavController().navigate(R.id.action_UnpublishedAds_to_Detail,
bundle_id)
navController!!.navigate(
R.id.action_allUnpublishedAdsFragment_to_adsDetailFragment,
bundle_id
)
}
}
private fun setupViewModel(token: String, page: String) {
LoadingDialog.show(requireContext(), { ld ->
recy_unpublished_ads.layoutManager = LinearLayoutManager(activity)
val decoration = DividerItemDecoration(activity, DividerItemDecoration.VERTICAL)
recy_unpublished_ads.addItemDecoration(decoration)
viewModel = ViewModelProvider(this).get(MainViewmodels::class.java)
unpublishedAdsAdapter = UnpublishedAdsAdapter()
recy_unpublished_ads.adapter = unpublishedAdsAdapter
viewModel.adsListObserve().observe({ lifecycle }, { model ->
items.clear()
items.addAll(model.adsList!!)
unpublishedAdsAdapter.setUpdateData(items)
ld.dismiss()
btn_continue.visibility = View.VISIBLE
})
viewModel.getAdsList(token, page)
})
}
fun continueAds() {
var isTouched=false
btn_continue.setOnClickListener {
isTouched=true
newpage = newpage + 1
Log.i("CONTINUE", newpage.toString())
setupViewModel(token, newpage.toString())
unpublishedAdsAdapter.notifyDataSetChanged()
isTouched=false
}
}
RetrofitInstance class
class RetrofitInstance {
companion object{
fun getRetrofitInstance (): Retrofit{
// val interceptor = HttpLoggingInterceptor()
// interceptor.setLevel(HttpLoggingInterceptor.Level.BODY)
// val client: OkHttpClient = OkHttpClient.Builder().addInterceptor(interceptor).build()
val okHttpClient: OkHttpClient = OkHttpClient.Builder()
.readTimeout(60, TimeUnit.SECONDS)
.connectTimeout(60, TimeUnit.SECONDS)
.build()
return Retrofit.Builder()
.baseUrl(BASEURL)
.addConverterFactory(GsonConverterFactory.create())
.client(okHttpClient)
.build()
}
}
}
my adapter:
class UnpublishedAdsAdapter : RecyclerView.Adapter<UnpublishedAdsAdapter.MyViewHolder>() {
var items = ArrayList<M_Ads>()
var itemClickListener: ((item: M_Ads, position: Int) -> Unit)? = null
lateinit var mcontext: Context
class ItemViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView)
class LoadingViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView)
fun setUpdateData(items: ArrayList<M_Ads>) {
this.items = items
notifyDataSetChanged()
}
class MyViewHolder(view: View) : RecyclerView.ViewHolder(view) {
val img_ads = view.findViewById<ImageView>(R.id.img_recy_ads)
val txt_title = view.findViewById<TextView>(R.id.txt_recy_ads_title)
val txt_accountType = view.findViewById<TextView>(R.id.txt_recy_ads_acctype)
fun bind(data: M_Ads) {
txt_title.setText(data.title)
txt_accountType.setText(data.accountType)
if (!data.image1.equals("")) {
Picasso.with(img_ads.context).load(data.image1).into(img_ads)
} else {
}
}
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyViewHolder {
mcontext = parent.context
return if (viewType == Constant.VIEW_TYPE_ITEM) {
val view = LayoutInflater.from(parent.context)
.inflate(R.layout.row_recy_unpublished_ads, parent, false)
MyViewHolder(view)
} else {
val view =
LayoutInflater.from(mcontext).inflate(R.layout.progress_loading, parent, false)
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
view.progressbar.indeterminateDrawable.colorFilter =
BlendModeColorFilter(Color.WHITE, BlendMode.SRC_ATOP)
} else {
view.progressbar.indeterminateDrawable.setColorFilter(
Color.WHITE,
PorterDuff.Mode.MULTIPLY
)
}
MyViewHolder(view)
}
}
override fun onBindViewHolder(holder: MyViewHolder, position: Int) {
holder.bind(items.get(position))
handleClick(holder)
}
fun handleClick(holder: UnpublishedAdsAdapter.MyViewHolder) {
holder.itemView.setOnClickListener {
val position = holder.adapterPosition
itemClickListener?.invoke(items.get(position), position)
}
}
override fun getItemCount(): Int {
return items.size
}
my Viewmodel:
class MainViewmodels:ViewModel() {
lateinit var getAds:MutableLiveData<Main_ModelAds>
init {
getAds= MutableLiveData<Main_ModelAds>()
}
fun adsListObserve():MutableLiveData<Main_ModelAds>{
return getAds
}
fun getAdsList(token:String,page:String){
viewModelScope.launch(Dispatchers.IO) {
try {
Log.i("ERRORRES",token + "")
val retrofitInstance=RetrofitInstance.getRetrofitInstance().create(RetrofitService::class.java)
val response=retrofitInstance.unPublishedAdsList(token,page)
getAds.postValue(response)
}catch (ex:Exception){
Log.i("ERRORRES", ex.message.toString() + "")
}
}
}

Answer 1

What you want here is to update the list that you are showing when the user clicks the button.
In this case you should use ListAdapter.
You can refer to this article for implementation:
https://developer.android.com/reference/androidx/recyclerview/widget/ListAdapter