Develop Reference

ListAdapter submitlist not update after deleting the data instead its giving me duplicate data

when i try to delete first row i get first row back and with duplicate second row
enter image description here
after delete any row from the list gives me duplicate data like this
enter image description here
This is my Adapter class. On my deleteItem function position is passed from fragment class and
it is supposed to delete an item from the given position and update the list but its rendering the duplicate data.
class MyListAdapter :ListAdapter<Article,MyListAdapter.MyViewHolder>(MyDiffUtil()) {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyViewHolder {
val view = LayoutInflater.from(parent.context).inflate(R.layout.recycler_item,parent,false)
return MyViewHolder(view)
}
override fun onBindViewHolder(holder: MyViewHolder, position: Int) {
val item = getItem(position)
holder.onBind(item)
// to click each item of list
holder.itemView.setOnClickListener {
onItemClickListener?.let {it(item) }
}
}
class MyViewHolder(itemView :View) : RecyclerView.ViewHolder(itemView)
{
fun onBind(article: Article) = with(itemView)
{
Glide.with(this)
.load(article.urlToImage)
.error(R.drawable.notfound)
.into(imageView)
webSource.text = article.source?.name
newsDate.text = article.publishedAt
newsTitle.text = article.title
newsDescription.text = article.description
}
}
// lamda function for handling web view
private var onItemClickListener : ((Article) -> Unit)? = null
fun setOnItemClickListener(listener : (Article) ->Unit)
{
onItemClickListener = listener
}
// implementing diffutil class
class MyDiffUtil : DiffUtil.ItemCallback<Article>()
{
override fun areItemsTheSame(oldItem: Article, newItem: Article): Boolean {
return oldItem.url == newItem.url
}
override fun areContentsTheSame(oldItem: Article, newItem: Article): Boolean {
return oldItem == newItem
}
}
fun deleteItem(pos : Int)
{
var myl = ArrayList<Article>()
val currentList= currentList.toMutableList()
currentList.removeAt(pos)
myl.addAll(currentList)
submitList(myl)
}
}
`
I tried to delete the saved news from the ListAdapter and update the recycler view with animation of DiffUtill class but its not updating the recycler view and
giving duplicate data . How can i delete data with diffutil animation as its normal way. Thanks in advance.
this is my fragment
package com.example.news.Fragments
class SavedNews : Fragment() {
lateinit var mymainViewModel: MainViewModel
lateinit var databaseObject: MyDataBase
lateinit var myAdapter: MyListAdapter
lateinit var convertedArticleList : ArrayList<Article>
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
myAdapter = MyListAdapter()
convertedArticleList = ArrayList()
return inflater.inflate(R.layout.fragment_saved_news, container, false)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
savedNewsRecyclerView.layoutManager = LinearLayoutManager(activity,LinearLayoutManager.VERTICAL,
false)
savedNewsRecyclerView.adapter = myAdapter
ItemTouchHelper(object :ItemTouchHelper.SimpleCallback(0,ItemTouchHelper.RIGHT){
override fun onMove(
recyclerView: RecyclerView,
viewHolder: RecyclerView.ViewHolder,
target: RecyclerView.ViewHolder
): Boolean {
// this method is called
// when the item is moved.
return true
}
override fun onSwiped(viewHolder: RecyclerView.ViewHolder, direction: Int) {
// this method is called when we swipe our item to right direction.
// on below line we are getting the item at a particular position.
val deletedCourse: Article =
convertedArticleList.get(viewHolder.adapterPosition)
myAdapter.deleteItem(viewHolder.adapterPosition)
mymainViewModel.deleteSavedNews(deletedCourse.id!!)
// myAdapter.notifyItemRemoved(viewHolder.adapterPosition)
// myAdapter.submitList(myCurrentList)
// Snackbar.make(savedNewsRecyclerView,"Deleted" + deletedCourse.title,
// Snackbar.LENGTH_LONG).setAction(
// "Undo",
// View.OnClickListener {
//
// convertedArticleList.add(position,deletedCourse)
// myAdapter.notifyItemInserted(position)
// }
// ).show()
}
}).attachToRecyclerView(savedNewsRecyclerView)
}
override fun onResume() {
super.onResume()
Log.d("LIFE","ON Resume")
val myInterfaceObject = ApiInterface.MyObject.getInstance()
databaseObject = MyDataBase.MyObjectDB.getDBInstance(activity as MainActivity)
val myRepository = Repository(myInterfaceObject, databaseObject)
mymainViewModel = ViewModelProvider(
this,
MainViewModelFactory(myRepository)
).get(MainViewModel::class.java)
//listAdapter things
// show saved news in savednews fragment
lifecycleScope.launch(Dispatchers.Main) {
//abstract data from saved room database and converting likedartcile datacass object to
// Artticle data class article
mymainViewModel.abstractSavedNews().observe(viewLifecycleOwner, Observer {
it.forEach { eachLikedArticle ->
val obj = toArticle(eachLikedArticle)
convertedArticleList.add(obj)
}
myAdapter.submitList(convertedArticleList)
})
//clicking the item of save news
myAdapter.setOnItemClickListener {
val bundle = Bundle().apply {
putSerializable("article", it)
}
convertedArticleList.clear()
findNavController().navigate(R.id.action_savedNews_to_article, bundle)
}
}
}
private fun toArticle(rawObject: LikedArticle) = Article(
rawObject.author, rawObject.content,
rawObject.description, rawObject.publishedAt, rawObject.source, rawObject.title,
rawObject.url, rawObject.urlToImage, rawObject.id
)
}

There is not enough information to actually replicate how you're trying to use this in your Fragment/Activity but without changing your code too much, this works (note I used view binding):
class MyListAdapter :
ListAdapter<Article, MyViewHolder>(MyDiffUtil()) {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) = MyViewHolder(
RecyclerItemBinding.inflate(
LayoutInflater.from(parent.context),
parent,
false
)
)
override fun onBindViewHolder(holder: MyViewHolder, position: Int) {
val item = getItem(position)
holder.onBind(item)
}
fun deleteItem(pos: Int) {
var myl = ArrayList<Article>()
val currentList = currentList.toMutableList()
currentList.removeAt(pos)
myl.addAll(currentList)
submitList(myl)
}
}
class MyViewHolder(private val binding: RecyclerItemBinding) : RecyclerView.ViewHolder(binding.root) {
fun onBind(article: Article) = with(binding) {
textView.text = article.url
}
}
class MyDiffUtil : DiffUtil.ItemCallback<Article>() {
override fun areItemsTheSame(oldItem: Article, newItem: Article): Boolean {
return oldItem.url == newItem.url
}
override fun areContentsTheSame(oldItem: Article, newItem: Article): Boolean {
return oldItem == newItem
}
}
Overall this should work.
You can also refactor deleteItem to something more meaningful:
fun deleteItem(pos: Int) {
val oldList = currentList.toMutableList()
oldList.removeAt(pos)
val updatedList = oldList
submitList(updatedList)
}

How can I display firebase data in a fragment with recyclerview? Kotlin Android Studio

hello I have an activity that has a navigation bar and fragments inside, in one of my fragments I save data in firebase, I want to get those data and display it in other fragment with recycler view. I watched a tutorial on youtube to do it cuz my teacher didn't teach us anything, the issue is the fragment that was supposed the display the data shows nothing, it's blank but I didn't understand why cuz I'm really new to this, if someone can take a look at my code and help me I would really appreciate it
This is my data class
data class Event(var eventName: String, var eventTime:String?=null)
This is ViewModel
class EventViewModel :ViewModel() {
private val repository : EventRepository
private val _allEvents = MutableLiveData<List<Event>>()
val allEvents : LiveData<List<Event>> = _allEvents
init {
repository= EventRepository().getInstance()
repository.loadEvents(_allEvents)
}
}
This is Repository
class EventRepository {
private val databaseReference: DatabaseReference= FirebaseDatabase.getInstance().getReference("PetEvents")
#Volatile private var INSTANCE : EventRepository ?=null
fun getInstance() : EventRepository{
return INSTANCE ?: synchronized(this) {
val instance = EventRepository()
INSTANCE=instance
instance
}
}
fun loadEvents(eventList : MutableLiveData<List<Event>>){
databaseReference.addValueEventListener(object:ValueEventListener{
override fun onDataChange(snapshot: DataSnapshot) {
try {
val _eventList : List<Event> = snapshot.children.map { dataSnapshot ->
dataSnapshot.getValue(Event::class.java)!!
}
eventList.postValue(_eventList)
}
catch (e: Exception){
}
}
override fun onCancelled(error: DatabaseError) {
TODO("Not yet implemented")
}
})
}
}
This is Adapter
class EventAdapter : RecyclerView.Adapter<EventAdapter.MyViewHolder>() {
private var eventList =ArrayList<Event>()
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyViewHolder {
val itemView = LayoutInflater.from(parent.context).inflate(
R.layout.event_item_cell,
parent, false
)
return MyViewHolder(itemView)
}
override fun onBindViewHolder(holder: MyViewHolder, position: Int) {
val currentItem = eventList[position]
holder.eventName.text =currentItem.eventName
holder.eventTime.text =currentItem.eventTime
}
override fun getItemCount(): Int {
return eventList.size
}
fun updateEventList(eventList: List<Event>){
this.eventList.clear()
this.eventList.addAll(eventList)
notifyDataSetChanged()
}
class MyViewHolder(itemView: View): RecyclerView.ViewHolder(itemView){
val eventName :TextView = itemView.findViewById(R.id.txEventName)
val eventTime :TextView = itemView.findViewById(R.id.txEventTime)
}
}
And this is the fragment I wish to display the data
private lateinit var viewModel : EventViewModel
private lateinit var eventRecyclerView: RecyclerView
lateinit var adapter: EventAdapter
class MainFragment : Fragment() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
}
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
return inflater.inflate(R.layout.fragment_main, container, false)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
eventRecyclerView=view.findViewById(R.id.recyclerView)
eventRecyclerView.layoutManager= LinearLayoutManager(context)
eventRecyclerView.setHasFixedSize(true)
adapter = EventAdapter()
eventRecyclerView.adapter= adapter
viewModel = ViewModelProvider(this).get(EventViewModel::class.java)
viewModel.allEvents.observe(viewLifecycleOwner, Observer {
adapter.updateEventList(it)
})
}
}
In my fragment xml I put a recycler view, there's no issue about that
And my item cell is a cardview idk if it has anything to with the problem I'm getting tho

item are updating while scrolling up reyclerview android?

i am making an app in which i have to insert data into reyclerview , the recyclerview is working fine but the problem is that when i scroll it up adapter reupdate the data , so to solve this issue the code looks fine but still getting this issue ....................................................
BaseClass
abstract class MultiViewModelBaseAdapter<M : Model, VDB : ViewDataBinding>(private var diffCallback: DiffUtil.ItemCallback<M>) : ListAdapter<M ,BaseViewHolder<VDB>>(diffCallback) {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): BaseViewHolder<VDB> {
val inflator = LayoutInflater.from(parent.context)
val binding = createBinding(viewType, inflator, parent)
return BaseViewHolder(binding)
}
abstract fun createBinding(viewType: Int, inflater: LayoutInflater, parent: ViewGroup) : VDB
override fun onBindViewHolder(holder: BaseViewHolder<VDB>, position: Int) {
bind(holder.mBinding, getItem(position), position)
holder.mBinding.executePendingBindings()
}
abstract fun bind(binding: VDB, item: M, position: Int)
abstract fun onDataChanged(values: Boolean)}
}
Adapter
class LanguageAdapter(
private val context: Context,
private val mViewModel: LanguageListViewModel,
private val onClickListener: OnItemClickListener<String>
) : MultiViewModelBaseAdapter<LanguageSupportModel, ViewDataBinding>(diffCallback) {
companion object {
private val ADS = 1
private val LANGUAGES = 2
val diffCallback = object : DiffUtil.ItemCallback<LanguageSupportModel>() {
override fun areItemsTheSame(
oldItem: LanguageSupportModel,
newItem: LanguageSupportModel
): Boolean = oldItem.dataId == newItem.dataId
/**
* Note that in kotlin, == checking on data classes compares all contents, but in Java,
* typically you'll implement Object#equals, and use it to compare object contents.
*/
override fun areContentsTheSame(
oldItem: LanguageSupportModel,
newItem: LanguageSupportModel
): Boolean = oldItem == newItem
}
}
override fun getItemId(position: Int): Long {
return position.toLong()
}
override fun getItemViewType(position: Int): Int {
return position
}
override fun createBinding(viewType: Int, inflater: LayoutInflater, parent: ViewGroup): ViewDataBinding {
return DataBindingUtil.inflate(inflater, R.layout.language_view, parent, false)
}
override fun bind(binding: ViewDataBinding, item: LanguageSupportModel, position: Int) {
binding as LanguageViewDataBinding
binding.apply {
language = item
//click
}
}
override fun onDataChanged(values: Boolean) {}
}
Fragment
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
val languageAdapter = LanguageAdapter(requireContext(), mViewModel, this ,lifecycleScope)
languageAdapter.submitList(LanguageArray.arrayValues())
reyclerview.layoutManager = LinearLayoutManager(context, LinearLayoutManager.VERTICAL, false)
adapter = languageAdapter
}

If You will Use Paging concept in Scrolling then it will Solve.
In the JAVA or KOTLIN We can implement.. like..
import androidx.viewpager.widget.PagerAdapter;
Then extends it into Adapter Class.
public void addList(List<ClsList> list) {
this.mResources = list;
notifyDataSetChanged(); // also this main line
}
Problem Solve.
☻♥ Have Fun..

Textview dispalys "androidx.livecycle.CoroutineLiveData"

I want to display the sum of a column from my room database in a textview.
After implementing my Query and setting the text of the Textview, it displays the following:
androidx.lifecycle.CoroutineLiveData#76f6edd
Any idea why this happens? Is it because my Query does not work or my way of implementign it is wrong?
It is my first time ever of actually programming. I know probably most of my code is not 100% correct, but I am working on it.
The Query from my Dao:
#Query("SELECT SUM(total)AS sum_total FROM receipt_table")
fun getSum(): Flow<Float>
The Fragment:
#AndroidEntryPoint
class HistoryFragment : Fragment(R.layout.fragment_history) {
private val viewModel: PurchaseViewmodel by viewModels()
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
return inflater.inflate(R.layout.fragment_history, container, false)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
val binding = FragmentHistoryBinding.bind(view)
val exampleAdapter = ExampleAdapter()
binding.apply{
recyclerView.apply{
layoutManager = LinearLayoutManager(requireContext())
adapter = exampleAdapter
}
totalSumTextView.apply {
val totalSum = viewModel.totalSum
text = totalSum.toString()
}
ItemTouchHelper(object : ItemTouchHelper.SimpleCallback(0, ItemTouchHelper.LEFT or ItemTouchHelper.RIGHT) {
override fun onMove(
recyclerView: RecyclerView,
viewHolder: RecyclerView.ViewHolder,
target: RecyclerView.ViewHolder
): Boolean {
return false
}
override fun onSwiped(viewHolder: RecyclerView.ViewHolder, direction: Int) {
val receipt = exampleAdapter.currentList[viewHolder.adapterPosition]
viewModel.onSwipe(receipt)
}
}).attachToRecyclerView(recyclerView)
}
setFragmentResultListener("add_receipt_request"){_,bundle ->
val result = bundle.getInt("add_receipt_request")
viewModel.onAddResult(result)
}
viewModel.receipts.observe(viewLifecycleOwner){
exampleAdapter.submitList(it)
}
viewLifecycleOwner.lifecycleScope.launchWhenStarted {
viewModel.addTaskEvent.collect { event->
when(event){
is PurchaseViewmodel.TasksEvent.ShowUndoDelete -> {
Snackbar.make(requireView(),"Tasks deleted", Snackbar.LENGTH_LONG)
.setAction("UNDO"){
viewModel.unDoDeleteClick(event.receipts)
}.show()
}
}
}
}
}
}
And the Viewmodel:
#HiltViewModel
class PurchaseViewmodel #Inject constructor(
private val receiptDao: ReceiptDao
): ViewModel() {
private val tasksEventChannel = Channel<TasksEvent>()
val addTaskEvent = tasksEventChannel.receiveAsFlow()
val receipts = receiptDao.getAllReceipts().asLiveData()
val totalSum = receiptDao.getSum().asLiveData()
fun onAddResult(result: Int){
when (result){
ADD_RECEIPT_RESULT_OK ->showReceiptSavedConfirmation("Receipt has been saved")
}
}
private fun showReceiptSavedConfirmation (text: String) = viewModelScope.launch {
tasksEventChannel.send(TasksEvent.ShowReceiptSavedConfirmation(text))
}
fun onSwipe (receipts: Receipts) = viewModelScope.launch {
receiptDao.delete(receipts)
tasksEventChannel.send(TasksEvent.ShowUndoDelete(receipts))
}
fun unDoDeleteClick (receipts: Receipts) = viewModelScope.launch {
receiptDao.insert(receipts)
}
sealed class TasksEvent {
data class ShowReceiptSavedConfirmation(val msg: String) : TasksEvent()
data class ShowUndoDelete(val receipts: Receipts) : TasksEvent()
}
}

You are getting a LiveData object here, not just a value:
val totalSum = receiptDao.getSum().asLiveData()
When you call:
totalSum.toString()
It calls toString method on the LiveData object that the reason, why you have "androidx.lifecycle.CoroutineLiveData#76f6edd" inside your TextView.
To fix the issue, just replace:
totalSumTextView.apply {
val totalSum = viewModel.totalSum
text = totalSum.toString()
}
with:
viewModel.totalSum.observe(this) { totalSumTextView.text = it}
Detailed review, how to work with a LiveData you can find here:
https://developer.android.com/topic/libraries/architecture/livedata

Kotlin RecycleView does not work correctly

I want to create a small application that once the user clicks on floating button action to add element. It will be added automatically
to the top of the recycle view.
I have created for this A main activity which contains the fragment of the recycler and the add flotten.
Once the user clicks on this button a fragmented dialog is shown to insert the element. Once the user confirms i want to add the new element to the top of the recycle view.
TO did I used a global array which contains the item.
I have not implemented the logic yet for that. But what surprised me once I click on confirm button of the shown dialog the element added correctly to the global array, however, the recycle view on his own without any action on it duplicate the latest element.
I used the model view presenter for that and here are my diff classes
1.MainActivity
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
addFragment(InterFragment(), R.id.container)
fab.setOnClickListener { view ->
val dialog = IntervAddFragment()
val ft = supportFragmentManager.beginTransaction()
dialog.show(ft, ContentValues.TAG)
}
}
}
2.ADDFragmet
class IntervAddFragment : DialogFragment(), AddContract.View
{
val presenter: AddPresenter by lazy { AddPresenter(this) }
var dat=""
var plom=""
var typ=""
override fun onCreate(savedInstanceState: Bundle?) { ....}
override fun onStart() {.... }
override fun onCreateView(inflater: LayoutInflater?, parent: ViewGroup?, state: Bundle?): View? {...}
override fun onViewCreated(view: View?, savedInstanceState: Bundle?) {....}
fun on_confirmClick()
{
presenter.on_confirmClick(dat,plom,typ)
Log.e("errrr",presenter.getList().toString())
dismiss()
}
fun fillSpinerPlom(view : View?) {.... }
fun fillSpinerType(view : View?) {.... }
private fun updateDateInView(datep:String) {....}
}
3.IntervFragement
InterFragment: Fragment(), InterContract.View {
var views: View? = null
var List_inter_adapter: InterListAdapter? = null
private var recyclerView: RecyclerView? = null
val presenter: InterventionPresenter by lazy { InterventionPresenter(this) }
override fun onCreateView(inflater: LayoutInflater?, container: ViewGroup?,
savedInstanceState: Bundle?): View? {.... }
interface ClickListener {
fun onClick(view: View, position: Int)
fun onLongClick(view: View?, position: Int)
}
internal class RecyclerTouchListener(context: Context, recyclerView: RecyclerView, private val clickListener: ClickListener?) : RecyclerView.OnItemTouchListener {..... }
override fun onInterceptTouchEvent(rv: RecyclerView, e: MotionEvent): Boolean {.....}
override fun onViewCreated(view: View?, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
recyclerView = views!!.findViewById<View>(R.id.interv_item_listview) as RecyclerView
List_inter_adapter = InterListAdapter(activity, presenter.getList(true))
recyclerView!!.adapter = List_inter_adapter
recyclerView!!.layoutManager = LinearLayoutManager(activity)
}
}
4.InterPresenter
class InterventionPresenter(val view: InterContract.View)
{
fun getList(firstTime:Boolean): LinkedList<InterItem> {
if(firstTime)
return populateList().list
else
return items
}
fun populateList(): ListInter
{
val item1 = InterItem(1, DateT(2018, Calendar.FEBRUARY, 6).date, plomb.get(0), types.get(0))
val item2 = InterItem(2, DateT(2018, Calendar.MARCH, 8).date, plomb.get(1), types.get(1))
val item3= InterItem(3, DateT(2018, Calendar.MAY, 10).date, plomb.get(2), types.get(2))
val lstint = ListInter()
lstint.list= LinkedList(listOf(item1, item2, item3))
items=lstint.list
return lstint
}
companion object {
val plomb= LinkedList<String>(listOf("Dina", "Lili", "Wiseem"))
val types= LinkedList<String>(listOf("type1","type2","type3"))
lateinit var items: LinkedList<InterItem>
}
}
5.ADD Presenter
class AddPresenter(val view: AddContract.View)
{
fun on_confirmClick(date:String,plom:String,type:String)
{
val item= InterItem(items.size+1,date,plom,type)
items.push(item)
}
fun getList(): LinkedList<InterItem> {
return items
}
fun getplom(): LinkedList<String>
{ return plomb
}
fun getType(): LinkedList<String>
{ return types
}
}
6.InterListAdapter
class InterListAdapter(private val context: Context, linkedList: LinkedList<InterItem>) : RecyclerView.Adapter<InterListAdapter.ViewHolder>()
{
internal var linkedList = LinkedList<InterItem>()
private val inflater: LayoutInflater
//private lateinit var listener: OnTaskSelected
init {... }
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {... }
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
holder.numero?.text=(linkedList[position].numero).toString()
holder.date?.text=linkedList[position].date
holder.plom?.text=linkedList[position].plom
holder.type?.text=linkedList[position].type
}
override fun getItemCount(): Int {
return linkedList.size
}
inner class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
var numero: TextView?=null
var date: TextView?=null
var plom: TextView?=null
var type: TextView?=null
var btn_delete: Button?=null
var btn_update: Button?=null
init {
numero = itemView.findViewById(R.id.numero)
date = itemView.findViewById(R.id.date)
plom = itemView.findViewById(R.id.plom)
type = itemView.findViewById(R.id.type)
btn_delete = itemView.findViewById(R.id.btn_supprimer)
btn_update = itemView.findViewById(R.id.btn_modifier)
}
}
}
and here is the ListInter
class ListInter
{
var list= LinkedList<InterItem>()
get() = field
set(value){field = value}
}

RecyclerView can't handle array change event by itself. So, you should notify it by calling the following after you've added element to array:
recyclerView.getAdapter().notifyItemInserted(items.size() - 1)