RecyclerView is not updated when an update occurs in Room - android

I have a RecyclerView where an item can be edited via a DialogFragment, so when an item is clicked a Dialog is shown, then I can change some properties of that item, the issue is that RecyclerView is not updated with the updated properties and I have to force a notifyItemChanged when the Dialog is closed.
When an item in RecyclerView is clicked I set a MutableLiveData in my ViewModel so then it can be manipulated in the Dialog.
My ViewModel looks like this:
#HiltViewModel
class DocumentProductsViewModel #Inject constructor(private val repository: DocumentProductsRepository) :
ViewModel() {
val barcode = MutableLiveData<String>()
private val _selectedProduct = MutableLiveData<DocumentProduct>()
val selectedProduct: LiveData<DocumentProduct> = _selectedProduct
private val _selectedDocumentId = MutableLiveData<Long>()
val selectedDocumentId: LiveData<Long> = _selectedDocumentId
val products: LiveData<List<DocumentProduct>> = _selectedDocumentId.switchMap { documentId ->
repository.getDocumentProducts(documentId).asLiveData()
}
fun insert(documentProduct: DocumentProduct) = viewModelScope.launch {
repository.insert(documentProduct)
}
fun setProductQuantity(quantity: Float) {
_selectedProduct.value = _selectedProduct.value.also {
it?.timestamp = System.currentTimeMillis()
it?.quantity = quantity
}
update()
}
fun start(documentId: Long?) = viewModelScope.launch{
if (documentId == null) {
_selectedDocumentId.value = repository.getHeaderByType("Etichette")?.id
}
documentId?.let { documentId ->
_selectedDocumentId.value = documentId
}
}
fun select(product: DocumentProduct) {
_selectedProduct.value = product
}
fun delete() = viewModelScope.launch {
_selectedProduct.value?.let { repository.delete(it) }
}
private fun update() = viewModelScope.launch {
_selectedProduct.value?.let { repository.update(it) }
}
}
And in my fragment I'm subscribed to products as this:
private fun initRecyclerView() {
binding.rvProducts.adapter = adapter
viewModel.products.observe(viewLifecycleOwner) { products ->
val productsCount = products.count()
binding.tvProductsCount.text =
resources.getQuantityString(R.plurals.articoli, productsCount, productsCount)
// TODO: create amount string and set it with resources
binding.tvProductsAmount.text = productsCount.toEuro()
adapter.submitList(products)
binding.rvProducts.smoothScrollToPosition(adapter.itemCount - 1)
}
initSwipe(adapter)
}
When setProductQuantity is called the RecyclerView remains unchanged until notify is called while delete works fine without the necessity of calling any notify on RecyclerView.
UPDATE:
The item position is actually changed in RecyclerView as it's sorted by it's last changed timestamp BUT not the quantity field.
Here is my Adapter:
class DocumentProductsListAdapter : ListAdapter<DocumentProduct, DocumentProductsListAdapter.ViewHolder>(ProductDiffCallback) {
override fun onCreateViewHolder(viewGroup: ViewGroup, viewType: Int): ViewHolder {
val view: View = LayoutInflater.from(viewGroup.context)
.inflate(R.layout.layout_item, viewGroup, false)
return ViewHolder(view)
}
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
val product = getItem(position)
holder.bind(product)
}
class ViewHolder(view: View) : RecyclerView.ViewHolder(view) {
val barcode: TextView = itemView.findViewById(R.id.barcode)
val quantity: TextView = itemView.findViewById(R.id.quantity)
val description: TextView = itemView.findViewById(R.id.description)
val unitOfMeasure: TextView = itemView.findViewById(R.id.unitOfMeasure)
fun bind(product: DocumentProduct) {
barcode.text = product.barcode
quantity.text = product.quantity.formatForQta().replace(".", ",")
if (product.labelType != null && product.labelType != "") {
unitOfMeasure.text = product.labelType
} else {
unitOfMeasure.text = product.unitOfMeasure?.lowercase(Locale.ITALIAN)
}
description.text = product.description ?: "-"
}
}
}
object ProductDiffCallback : DiffUtil.ItemCallback<DocumentProduct>() {
override fun areItemsTheSame(oldItem: DocumentProduct, newItem: DocumentProduct): Boolean {
return oldItem.id == newItem.id
}
override fun areContentsTheSame(oldItem: DocumentProduct, newItem: DocumentProduct): Boolean {
return oldItem == newItem
}
}
data class DocumentProduct(
#PrimaryKey(autoGenerate = true)
var id: Long,
var barcode: String,
#Json(name = "desc")
var description: String?,
#ColumnInfo(defaultValue = "PZ")
#Json(name = "um")
var unitOfMeasure: String?,
#Json(name = "qta")
var quantity: Float,
#Json(name = "id_testata")
var documentId: Long,
#Json(name = "tipo_frontalino")
var labelType: String?,
var timestamp: Long?
) {
constructor(barcode: String, documentId: Long, labelType: String?) : this(
0,
barcode,
null,
"PZ",
1f,
documentId,
labelType,
null
)
override fun equals(other: Any?): Boolean {
return super.equals(other)
}
override fun hashCode(): Int {
return super.hashCode()
}
}

You have the implementations of areContentsTheSame() and areItemsTheSame() swapped.
areContentsTheSame() is asking if everything in the two items being compared is the same. Therefore, if the class has a proper equals()/hashcode() for all properties used by the ViewHolder, you can use oldItem == newItem. If you use a data class with all relevant properties in the primary constructor, then you don't need to manually override equals()/hashcode().
areItemsTheSame() is asking if the two items represent the same conceptual row item, with possible differences in their details. So it should be oldItem.id == newItem.id.
The problem with your data class is that you are overriding equals()/hashcode() without providing any implementation at all. This is effectively disabling the proper implementations that are provided by the data modifier by calling through to the super implementation in the Any class. You should not override them at all when you use data class.

Related

Even if the address of the list changes, does the address value of the property remain the same?

Currently, I am making a task in Android that changes the unit value of the list according to the toggle button and shows the list with the changed value.
I am observing the list using a ViewModel and LiveData.
So i use toList() to return a new list and overwrite the old list to observe the values.
However, the screen is not updated even though it has returned a new list.
I've tried debugging and I'm getting some incomprehensible results.
Obviously, the address values ​​of the old list and the new list are different, but even the unit of the old list has changed.
What happened?
Even if the addresses of Lists are different, do the values ​​of the old list and the new list change at the same time because the properties refer to the same place?
I'll show you the minimal code.
Fragment
// Change Unit
toggleButton.addOnButtonCheckedListener { _, checkedId, isChecked ->
if(isChecked) {
when(checkedId) {
R.id.kg -> vm.changeUnit("kg")
R.id.lb -> vm.changeUnit("lbs")
}
}
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
vm.items.observe(viewLifecycleOwner) { newList ->
adapter.submitList(newList)
}
}
WorkoutSetInfo
#Entity(
foreignKeys = [
ForeignKey(
entity = Workout::class,
parentColumns = arrayOf("workoutId"),
childColumns = arrayOf("parentWorkoutId"),
onDelete = ForeignKey.CASCADE
)
]
)
data class WorkoutSetInfo(
#PrimaryKey(autoGenerate = true)
val id: Long = 0,
val set: Int,
var weight: String = "",
var reps: String = "",
var unit: String = "kg",
val parentWorkoutId: Long = 0
)
Adapter
class DetailAdapter
: ListAdapter<WorkoutSetInfo, DetailAdapter.ViewHolder>(DetailDiffCallback()) {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
return ViewHolder(
ItemRoutineDetailBinding.inflate(
LayoutInflater.from(parent.context),
parent,
false
)
)
}
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
holder.bind(currentList[position])
}
inner class ViewHolder(val binding: ItemRoutineDetailBinding) : RecyclerView.ViewHolder(binding.root) {
private var weightTextWatcher: TextWatcher? = null
private var repTextWatcher: TextWatcher? = null
fun bind(item: WorkoutSetInfo) {
binding.set.text = item.set.toString()
binding.weight.removeTextChangedListener(weightTextWatcher)
binding.unit.text = item.unit
binding.rep.removeTextChangedListener(repTextWatcher)
weightTextWatcher = object : TextWatcher {
override fun beforeTextChanged(p0: CharSequence?, p1: Int, p2: Int, p3: Int) { }
override fun onTextChanged(p0: CharSequence?, p1: Int, p2: Int, p3: Int) { }
override fun afterTextChanged(w: Editable?) {
if(!binding.weight.hasFocus())
return
item.weight = w.toString()
}
}
repTextWatcher = object : TextWatcher {
override fun beforeTextChanged(s: CharSequence?, start: Int, count: Int, after: Int) { }
override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) { }
override fun afterTextChanged(r: Editable?) {
if(!binding.rep.hasFocus())
return
item.reps = r.toString()
}
}
binding.apply {
weight.setTextIfDifferent(item.weight)
weight.addTextChangedListener(weightTextWatcher)
rep.setTextIfDifferent(item.reps)
rep.addTextChangedListener(repTextWatcher)
}
}
}
}
DiffUtil*
class DetailDiffCallback : DiffUtil.ItemCallback<WorkoutSetInfo>() {
override fun areItemsTheSame(
oldItem: WorkoutSetInfo,
newItem: WorkoutSetInfo
): Boolean {
return (oldItem.id == newItem.id)
}
override fun areContentsTheSame(
oldItem: WorkoutSetInfo,
newItem: WorkoutSetInfo
): Boolean {
return oldItem == newItem
}
}
ViewModel
class DetailViewModel(application: Application, title: String) : ViewModel() {
private val workoutDao = DetailDatabase.getDatabase(application)!!.workoutDao()
private val repository: WorkoutRepository = WorkoutRepository(workoutDao, title)
private val _items: MutableLiveData<List<WorkoutSetInfo>> = MutableLiveData()
val items = _items
fun changeUnit(unit: String) {
repository.changeUnit(unit)
_items.postValue(repository.getList())
}
fun addSet() {
viewModelScope.launch(Dispatchers.IO){
repository.add()
_items.postValue(repository.getList())
}
}
fun deleteSet() {
repository.delete()
_items.postValue(repository.getList())
}
fun save() {
viewModelScope.launch(Dispatchers.IO) {
repository.save()
}
}
}
Repository
class WorkoutRepository(private val workoutDao : WorkoutDao, title: String) {
private val workout = Workout(title = title)
private val setInfoList = ArrayList<WorkoutSetInfo>()
fun changeUnit(unit: String) {
setInfoList.map { setInfo ->
setInfo.unit = unit
}
}
fun add() {
val item = WorkoutSetInfo(set = setInfoList.size + 1)
setInfoList.add(item)
}
fun delete() {
if(setInfoList.size != 0)
setInfoList.removeLast()
return
}
fun save() {
val workoutId = workoutDao.insertWorkout(workout)
val newWorkoutSetInfoList = setInfoList.map { setInfo ->
setInfo.copy(parentWorkoutId = workoutId)
}
workoutDao.insertSetInfoList(newWorkoutSetInfoList)
}
fun getList() : List<WorkoutSetInfo> = setInfoList.toList()
}
You'd need to post your observer code for any help with why it's not updating.
As for the weird behaviour, setInfoList contains a few WorkoutSetInfo objects, right? Let's call them A, B and C. When you call setInfoList.toList() you're creating a new container, which holds the same references to objects A, B and C. Because it's a separate list, you can add and remove items without affecting the original list, but any changes to the objects that both share will be reflected in both lists - because they're both looking at the same thing.
So when you do setInfoList.map { setInfo -> setInfo.unit = unit } (which should be forEach really, map creates a new list you're discarding) you're modifying A, B and C. So every list you've made that contains those objects will see those changes, including your old list.
Basically if you want each list to be independent, when you modify the list you need to create new instances of the items, which means copying your WorkoutSetInfo objects to create new ones, instead of updating the current ones. If it's a data class then you can do that fairly easily (so long as you don't have nested objects that need copying themselves):
// var so we can replace it with a new list
private var setInfoList = listOf<WorkoutSetInfo>()
fun changeUnit(unit: String) {
// create a new list, copying each item with a change to the unit property
setInfoList = setInfoList.map { setInfo ->
setInfo.copy(unit = unit)
}
}
You don't need to do toList() on getList anymore, since you're just passing the current version of the list, and that list will never change (because you'll just create a new one). Meaning you don't need that function, you can just make setInfoList public - and because I changed it to listOf which creates an immutable List, it's safe to pass around because it can't be modified.
The WorkoutSetInfo objects inside that list could still be modified externally though (e.g. by changing one of the items' unit value), so instead of making a new copy when you call changeUnit, you might want to do it when you call getList instead:
class WorkoutRepository(private val workoutDao : WorkoutDao, title: String) {
private val workout = Workout(title = title)
private val setInfoList = ArrayList<WorkoutSetInfo>()
// store the current unit here
private var currentUnit = "kg"
fun changeUnit(unit: String) {
currentUnit = unit
}
// return new List
fun getList() : List<WorkoutSetInfo> = setInfoList.map { it.copy(unit = currentUnit) }
}
Now everything that calls getList gets a unique list with unique objects, so they're all separate from each other. And if you don't actually need to store the current unit value, you could pass it in to getList instead of having a changeUnit function:
fun getList(unit: String) = setInfoList.map { it.copy(unit = unit) }

How to use different classes with only one LiveData list?

I have this interface and 2 classes, I know it's not the best approach here, but that's not the point now.
interface FilterItem {
val id: String
val name: String
val isChecked: ObservableField<Boolean>
fun reset()
}
data class Technology(
override val id: String,
override val name: String,
override val isChecked: ObservableField<Boolean> = ObservableField(),
) : FilterItem {
override fun reset() {
isChecked.set(false)
}
}
data class Project(
override val id: String,
override val name: String,
override val isChecked: ObservableField<Boolean> = ObservableField(),
) : FilterItem {
override fun reset() {
isChecked.set(false)
}
}
And then I have a ViewModel
private val _filterList = MutableLiveData<List<FilterItem>>().apply {
viewModelScope.launch {
value = loadSkills()
}
}
val filterList: LiveData<List<FilterItem>>
get() = _filterList
private fun loadSkills(): MutableList<FilterItem> {
val technologiesList: MutableList<FilterItem> = mutableListOf()
technologiesList.add(Technology("1", "Android"))
technologiesList.add(Technology("2", "Kotlin"))
return technologiesList
}
private fun loadProjects(): MutableList<FilterItem> {
val projectsList: MutableList<FilterItem> = mutableListOf()
projectsList.add(Project("1", "Project 1"))
projectsList.add(Project("2", "Project 2"))
return projectsList
}
I want to use the filterList so that is holds a list of Technologies or a list of Projects, depending on what BottomSheetDialog I'm opening.
showSkillsButton.setOnClickListener {
showFilterModal(filterViewModel.filterList, SKILLS)
}
showProjectsButton.setOnClickListener {
showFilterModal(filterViewModel.projects, PROJECTS)
}
I want to somehow use filterList only(I had 2 lists for skills and projects, but it would be nice if I could replace them with only 1 filterList).
Is there any way to do this? Or what would be the best approach?

Android Paging 3 - experiencing flickers, glitches or jumps in position when scrolling & loading new pages

Hello Guys im using Android Jetpack Paging library 3, I'm creating a news app that implements network + database scenario, and im following the codelab by google https://codelabs.developers.google.com/codelabs/android-paging , im doing it almost like in the codelab i almost matched all the operations shown in the examples https://github.com/android/architecture-components-samples/tree/main/PagingWithNetworkSample.
It works almost as it should...but my backend response is page keyed, i mean response comes with the list of news and the next page url, remote mediator fetches the data, populates the database, repository is set, viewmodel is set...
The problem is :
when recyclerview loads the data , following happens:recyclerview flickers, items jump, are removed , added again and so on.
I dont know why recyclerview or its itemanimator behaves like that , that looks so ugly and glitchy.
More than that, when i scroll to the end of the list new items are fetched and that glitchy and jumping effect is happening again.
I would be very grateful if you could help me, im sitting on it for three days , thank you very much in advance.Here are my code snippets:
#Entity(tableName = "blogs")
data class Blog(
#PrimaryKey(autoGenerate = true)
val databaseid:Int,
#field:SerializedName("id")
val id: Int,
#field:SerializedName("title")
val title: String,
#field:SerializedName("image")
val image: String,
#field:SerializedName("date")
val date: String,
#field:SerializedName("share_link")
val shareLink: String,
#field:SerializedName("status")
val status: Int,
#field:SerializedName("url")
val url: String
) {
var categoryId: Int? = null
var tagId: Int? = null
}
Here's the DAO
#Insert(onConflict = OnConflictStrategy.REPLACE)
suspend fun insertAll(blogs: List<Blog>)
#Query("DELETE FROM blogs")
suspend fun deleteAllBlogs()
#Query("SELECT * FROM blogs WHERE categoryId= :categoryId ORDER BY id DESC")
fun getBlogsSourceUniversal(categoryId:Int?): PagingSource<Int, Blog>
#Query("SELECT * FROM blogs WHERE categoryId= :categoryId AND tagId= :tagId ORDER BY id DESC")
fun getBlogsSourceUniversalWithTags(categoryId:Int?,tagId:Int?): PagingSource<Int, Blog>
NewsDatabaseKt
abstract class NewsDatabaseKt : RoomDatabase() {
abstract fun articleDAOKt(): ArticleDAOKt
abstract fun remoteKeyDao(): RemoteKeyDao
companion object {
#Volatile
private var INSTANCE: NewsDatabaseKt? = null
fun getDatabase(context: Context): NewsDatabaseKt =
INSTANCE ?: synchronized(this) {
INSTANCE ?: buildDatabase(context).also { INSTANCE = it }
}
private fun buildDatabase(context: Context) =
Room.databaseBuilder(context.applicationContext,
NewsDatabaseKt::class.java,
"news_database_kt")
.build()
}
RemoteMediator
#ExperimentalPagingApi
class BlogsRemoteMediator(private val categoryId: Int,
private val service: NewsAPIInterfaceKt,
private val newsDatabase: NewsDatabaseKt,
private val tagId : Int? = null ,
private val initialPage:Int = 1
) : RemoteMediator<Int, Blog>() {
override suspend fun initialize(): InitializeAction {
return InitializeAction.LAUNCH_INITIAL_REFRESH
}
override suspend fun load(loadType: LoadType, state: PagingState<Int, Blog>): MediatorResult {
try {
val page = when (loadType) {
REFRESH ->{
initialPage
}
PREPEND -> {
return MediatorResult.Success(endOfPaginationReached = true)}
APPEND -> {
val remoteKey = newsDatabase.withTransaction {
newsDatabase.remoteKeyDao().remoteKeyByLatest(categoryId.toString())
}
if(remoteKey.nextPageKey == null){
return MediatorResult.Success(endOfPaginationReached = true)
}
remoteKey.nextPageKey.toInt()
}
}
val apiResponse =
if(tagId == null) {
service.getCategoryResponsePage(RU, categoryId, page.toString())
}else{
service.getCategoryTagResponsePage(RU,categoryId,tagId,page.toString())
}
val blogs = apiResponse.blogs
val endOfPaginationReached = blogs.size < state.config.pageSize
newsDatabase.withTransaction {
// clear all tables in the database
if (loadType == LoadType.REFRESH) {
newsDatabase.remoteKeyDao().deleteByLatest(categoryId.toString())
if(tagId == null) {
newsDatabase.articleDAOKt().clearBlogsByCatId(categoryId)
}else {
newsDatabase.articleDAOKt().clearBlogsByCatId(categoryId,tagId)
}
}
blogs.map {blog ->
blog.categoryId = categoryId
if(tagId != null) {
blog.tagId = tagId
}
}
newsDatabase.remoteKeyDao().insert(LatestRemoteKey(categoryId.toString(),
apiResponse.nextPageParam))
newsDatabase.articleDAOKt().insertAll(blogs)
}
return MediatorResult.Success(
endOfPaginationReached = endOfPaginationReached
)
} catch (exception: IOException) {
return MediatorResult.Error(exception)
} catch (exception: HttpException) {
return MediatorResult.Error(exception)
}
}
PagingRepository
class PagingRepository(
private val service: NewsAPIInterfaceKt,
private val databaseKt: NewsDatabaseKt
){
#ExperimentalPagingApi
fun getBlogsResultStreamUniversal(int: Int, tagId : Int? = null) : Flow<PagingData<Blog>>{
val pagingSourceFactory = {
if(tagId == null) {
databaseKt.articleDAOKt().getBlogsSourceUniversal(int)
}else databaseKt.articleDAOKt().getBlogsSourceUniversalWithTags(int,tagId)
}
return Pager(
config = PagingConfig(
pageSize = 1
)
,remoteMediator =
BlogsRemoteMediator(int, service, databaseKt,tagId)
,pagingSourceFactory = pagingSourceFactory
).flow
}
}
BlogsViewmodel
class BlogsViewModel(private val repository: PagingRepository):ViewModel(){
private var currentResultUiModel: Flow<PagingData<UiModel.BlogModel>>? = null
private var categoryId:Int?=null
#ExperimentalPagingApi
fun getBlogsUniversalWithUiModel(int: Int, tagId : Int? = null):
Flow<PagingData<UiModel.BlogModel>> {
val lastResult = currentResultUiModel
if(lastResult != null && int == categoryId){
return lastResult
}
val newResult: Flow<PagingData<UiModel.BlogModel>> =
repository.getBlogsResultStreamUniversal(int, tagId)
.map { pagingData -> pagingData.map { UiModel.BlogModel(it)}}
.cachedIn(viewModelScope)
currentResultUiModel = newResult
categoryId = int
return newResult
}
sealed class UiModel{
data class BlogModel(val blog: Blog) : UiModel()
}
PoliticsFragmentKotlin
#ExperimentalPagingApi
class PoliticsFragmentKotlin : Fragment() {
private lateinit var recyclerView: RecyclerView
private lateinit var pagedBlogsAdapter:BlogsAdapter
lateinit var viewModelKt: BlogsViewModel
lateinit var viewModel:NewsViewModel
private var searchJob: Job? = null
#ExperimentalPagingApi
private fun loadData(categoryId:Int, tagId : Int? = null) {
searchJob?.cancel()
searchJob = lifecycleScope.launch {
viewModelKt.getBlogsUniversalWithUiModel(categoryId, tagId).collectLatest {
pagedBlogsAdapter.submitData(it)
}
}
}
#ExperimentalPagingApi
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?): View? {
val view = inflater.inflate(R.layout.fragment_blogs, container, false)
viewModelKt = ViewModelProvider(requireActivity(),Injection.provideViewModelFactory(requireContext())).get(BlogsViewModel::class.java)
viewModel = ViewModelProvider(requireActivity()).get(NewsViewModel::class.java)
pagedBlogsAdapter = BlogsAdapter(context,viewModel)
val decoration = DividerItemDecoration(context, DividerItemDecoration.VERTICAL)
recyclerView = view.findViewById(R.id.politics_recyclerView)
recyclerView.addItemDecoration(decoration)
initAdapter()
loadData(categoryId)
initLoad()
return view
}
private fun initLoad() {
lifecycleScope.launchWhenCreated {
Log.d("meylis", "lqunched loadstate scope")
pagedBlogsAdapter.loadStateFlow
// Only emit when REFRESH LoadState for RemoteMediator changes.
.distinctUntilChangedBy { it.refresh }
// Only react to cases where Remote REFRESH completes i.e., NotLoading.
.filter { it.refresh is LoadState.NotLoading }
.collect { recyclerView.scrollToPosition(0) }
}
}
private fun initAdapter() {
recyclerView.adapter = pagedBlogsAdapter.withLoadStateHeaderAndFooter(
header = BlogsLoadStateAdapter { pagedBlogsAdapter.retry() },
footer = BlogsLoadStateAdapter { pagedBlogsAdapter.retry() }
)
lifecycleScope.launchWhenCreated {
pagedBlogsAdapter.loadStateFlow.collectLatest {
swipeRefreshLayout.isRefreshing = it.refresh is LoadState.Loading
}
}
pagedBlogsAdapter.addLoadStateListener { loadState ->
// Only show the list if refresh succeeds.
recyclerView.isVisible = loadState.source.refresh is LoadState.NotLoading
// Show loading spinner during initial load or refresh.
progressBar.isVisible = loadState.source.refresh is LoadState.Loading
// Show the retry state if initial load or refresh fails.
retryButton.isVisible = loadState.source.refresh is LoadState.Error
// Toast on any error, regardless of whether it came from RemoteMediator or PagingSource
val errorState = loadState.source.append as? LoadState.Error
?: loadState.source.prepend as? LoadState.Error
?: loadState.append as? LoadState.Error
?: loadState.prepend as? LoadState.Error
errorState?.let {
Toast.makeText(context, "\uD83D\uDE28 Wooops ${it.error}", Toast.LENGTH_LONG
).show()
}
}
}
companion object {
#JvmStatic
fun newInstance(categoryId: Int, tags : ArrayList<Tag>): PoliticsFragmentKotlin {
val args = Bundle()
args.putInt(URL, categoryId)
args.putSerializable(TAGS,tags)
val fragmentKotlin = PoliticsFragmentKotlin()
fragmentKotlin.arguments = args
Log.d("meylis", "created instance")
return fragmentKotlin
}
}
BlogsAdapter
class BlogsAdapter(var context: Context?, var newsViewModel:NewsViewModel) :
PagingDataAdapter<BlogsViewModel.UiModel.BlogModel, RecyclerView.ViewHolder>
(REPO_COMPARATOR) {
private val VIEW = 10
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder {
return when (viewType) {
VIEW -> MyViewHolder(LayoutInflater.from(parent.context).inflate(R.layout.card_layout, parent, false))
}
}
override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) {
val uiModel = getItem(position)
if(uiModel == null){
if(uiModel is BlogsViewModel.UiModel.BlogModel){(holder as MyViewHolder).bind(null)}
}
if(uiModel is BlogsViewModel.UiModel.BlogModel){(holder as
MyViewHolder).bind(uiModel.blog)}
}
override fun getItemViewType(position: Int): Int {
return VIEW
}
companion object {
private val REPO_COMPARATOR = object : DiffUtil.ItemCallback<BlogsViewModel.UiModel.BlogModel>() {
override fun areItemsTheSame(oldItem: BlogsViewModel.UiModel.BlogModel, newItem: BlogsViewModel.UiModel.BlogModel): Boolean =
oldItem.blog.title == newItem.blog.title
override fun areContentsTheSame(oldItem: BlogsViewModel.UiModel.BlogModel, newItem: BlogsViewModel.UiModel.BlogModel): Boolean =
oldItem == newItem
}
}
MyViewHolder
class MyViewHolder(var container: View) : RecyclerView.ViewHolder(container) {
var cv: CardView
#JvmField
var mArticle: TextView
var date: TextView? = null
#JvmField
var time: TextView
#JvmField
var articleImg: ImageView
#JvmField
var shareView: View
var button: MaterialButton? = null
#JvmField
var checkBox: CheckBox
var progressBar: ProgressBar
private var blog:Blog? = null
init {
cv = container.findViewById<View>(R.id.cardvmain) as CardView
mArticle = container.findViewById<View>(R.id.article) as TextView
articleImg = container.findViewById<View>(R.id.imgvmain) as ImageView
//button = (MaterialButton) itemView.findViewById(R.id.sharemain);
checkBox = container.findViewById<View>(R.id.checkboxmain) as CheckBox
time = container.findViewById(R.id.card_time)
shareView = container.findViewById(R.id.shareView)
progressBar = container.findViewById(R.id.blog_progress)
}
fun bind(blog: Blog?){
if(blog == null){
mArticle.text = "loading"
time.text = "loading"
articleImg.visibility = View.GONE
}else {
this.blog = blog
mArticle.text = blog.title
time.text = blog.date
if (blog.image.startsWith("http")) {
articleImg.visibility = View.VISIBLE
val options: RequestOptions = RequestOptions()
.centerCrop()
.priority(Priority.HIGH)
GlideImageLoader(articleImg,
progressBar).load(blog.image, options)
} else {
articleImg.visibility = View.GONE
}
}
}
}
NewsApiInterface
interface NewsAPIInterfaceKt {
#GET("sort?")
suspend fun getCategoryResponsePage(#Header("Language") language: String, #Query("category")
categoryId: Int, #Query("page") pageNumber: String): BlogsResponse
#GET("sort?")
suspend fun getCategoryTagResponsePage(#Header("Language") language: String,
#Query("category") categoryId: Int,#Query("tag") tagId:Int, #Query("page") pageNumber: String)
:BlogsResponse
companion object {
fun create(): NewsAPIInterfaceKt {
val logger = HttpLoggingInterceptor()
logger.level = HttpLoggingInterceptor.Level.BASIC
val okHttpClient = UnsafeOkHttpClient.getUnsafeOkHttpClient()
return Retrofit.Builder()
.baseUrl(BASE_URL)
.client(okHttpClient)
.addConverterFactory(GsonConverterFactory.create())
.build()
.create(NewsAPIInterfaceKt::class.java)
}
}
}
I have tried setting initialLoadSize = 1
But the problem still persists
EDIT: Thanks for your answer #dlam , yes, it does , my network API returns the list of results ordered by id. BTW, items do this jump when the application is run offline as well.
Videos when refreshing and loading online
online loading and paging
online loading and paging(2)
Videos when refreshing and loading offline
offline loading and refreshing
Thanks again, here is my gist link https://gist.github.com/Aydogdyshka/7ca3eb654adb91477a42128de2f06ea9
EDIT
Thanks a lot to #dlam, when I set pageSize=10, jumping has disappeared...Then i remembered why i set pageSize=1 in the first place... when i refresh , 3 x pageSize of items are loaded, even if i overrided initialLoadSize = 10 , it still loads 3 x pageSize calling append 2x times after refresh , what could i be doing wrong, what's the correct way to only load first page when i refresh ?
Just following up here from comments:
Setting pageSize = 10 fixes the issue.
The issue was with pageSize being too small, resulting in PagingSource refreshes loading pages that did not cover the viewport. Since source refresh replaces the list and goes through DiffUtil, you need to provide an initialLoadSize that is large enough so that there is some overlap (otherwise scroll position will be lost).
BTW - Paging loads additional data automatically based on PagingConfig.prefetchDistance. If RecyclerView binds items close enough to the edge of the list, it will automatically trigger APPEND / PREPEND loads. This is why the default of initialLoadSize is 3 * pageSize, but if you're still experiencing additional loads, I would suggest either adjusting prefetchDistance, or increasing initialLoadSize further.
config = PagingConfig(
pageSize = PAGE_SIZE,
enablePlaceholders = true,
prefetchDistance = 3* PAGE_SIZE,
initialLoadSize = 2*PAGE_SIZE,
)
make sure enablePlaceholders is set to true and set the page size to around 10 to 20
recyclerview flickers becouse from dao you get items not the same order it was responded from network.
I will suggest you my solution.
we will get items from database order by primary key, databaseid, descending.
first of all delete autogenerated = true.
we will set databaseid manualy, in same order we got items from network.
next lets edit remoteMediator load function.
when (loadType) {
LoadType.PREPEND -> {
blogs.map {
val databaseid = getFirstBlogDatabaseId(state)?.databaseid?:0
movies.forEachIndexed{
index, blog ->
blog.databaseid = roomId - (movies.size -index.toLong())
}
}
}
LoadType.APPEND -> {
val roomId = getLastBlogDatabaseId(state)?.databaseid ?:0
blogs.forEachIndexed{
index, blog ->
blog.databaseid = roomId + index.toLong() + 1
}
}
LoadType.REFRESH -> {
blogs.forEachIndexed{
index, blog ->
blog.databaseid = index.toLong()
}
}
}
private fun getFirstBlogDatabaseId(state: PagingState<Int, Blog>): Blog? {
return state.pages.firstOrNull { it.data.isNotEmpty() }?.data?.firstOrNull()
}
private fun getLastBlogDatabaseId(state: PagingState<Int, Blog>): Blog? {
return state.lastItemOrNull()
}

RecyclerView make endless scrolling with JSON

I'm trying to make my Android App (I'm only experienced in iOS).
I created a RecyclerView that gets the data from a web. I tried everything to implement endless scrolling to load more items, but when I call the function to get the items, the entire RecyclerView loads again and no attach the new results on the bottom.
This is my code:
ConversationUser.kt
data class ConversationUser(
val message_nickname: String,
val message_image_thumb: String,
val message_large_thumb: String,
val message_modified: String,
val message_status: String,
val message_unread: Int,
val conv_id: String,
val message_dest: String) {
}
ConversacionesActivity.kt
class ConversacionesActivity : AppCompatActivity() {
// MARK: Variables
var user_token = ""
var user_id = ""
override fun onCreate(savedInstanceState: Bundle?) {
// User Defaults
val sharedPreferences = getSharedPreferences("Preferences", Context.MODE_PRIVATE)
user_token = sharedPreferences.getString("user_token", "")!!
user_id = sharedPreferences.getString("user_id", "")!!
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_conversaciones)
recyclerConv.addItemDecoration(DividerItemDecoration(this, LinearLayoutManager.VERTICAL))
getConversationsData()
recyclerConv.setLoadingListener(object : LoadingListener {
override fun onRefresh() {
//refresh data here
}
override fun onLoadMore() {
// load more data here
getConversationsData()
}
})
}
fun getConversationsData() {
val httpAsync = "https://mywebsite.com/conversations/${user_token}"
.httpPost()
.responseString { request, response, result ->
when (result) {
is Result.Failure -> {
val ex = result.getException()
println(ex)
}
is Result.Success -> {
val data = result.get()
runOnUiThread {
val conversaciones = processJson(data)
show(conversaciones)
return#runOnUiThread
}
}
}
}
httpAsync.join()
}
fun processJson(json: String): List<ConversationUser> {
val gson: Gson = GsonBuilder().create()
val conversaciones: List<ConversationUser> = gson.fromJson(
json,
Array<ConversationUser>::class.java
).toList()
return conversaciones
}
fun show(conversaciones: List<ConversationUser>) {
recyclerConv.layoutManager = LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false)
recyclerConv.adapter = AdaptadorConv(conversaciones, this, user_token, user_id)
}
AdaptadorConv.kt
class AdaptadorConv(
val conversaciones: List<ConversationUser> = ArrayList(),
val context: Context,
val user_token: String,
val user_id: String) : RecyclerView.Adapter<AdaptadorConv.ConvViewHolder>() {
override fun onBindViewHolder(holder: ConvViewHolder, position: Int) {
holder.convName.text = conversaciones[position].message_nickname
holder.convTime.text = conversaciones[position].message_modified
}
override fun getItemCount(): Int {
return conversaciones.size - 1
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ConvViewHolder {
val view: View = LayoutInflater.from(parent.context).inflate(
R.layout.conversaciones,
parent,
false
)
return ConvViewHolder(view)
}
class ConvViewHolder(vista: View): RecyclerView.ViewHolder(vista) {
val convImg: ImageView = itemView.findViewById(R.id.convImg)
val convStatus: ImageView = itemView.findViewById(R.id.convStatus)
val convName: TextView = itemView.findViewById(R.id.convName)
val convUnread: TextView = itemView.findViewById(R.id.convUnread)
val convTime: TextView = itemView.findViewById(R.id.convTime)
}
Thanks for any help or hint.
Please check your show () method, you are creating new Adapter every time with the new dataset. You have to append the new items to the adapter's list and adapter should be set to list once. Helpful tutorial can be found at here.

Could not complete scheduled request to refresh entries. ClientErrorCode: 3 Android Kotlin

Let me get straight to the point here the error in the logcat is:
Could not complete scheduled request to refresh entries. ClientErrorCode: 3
I have tested the Realm() part of the code and it fetched the right data. Basically, the app just crashes when it loads that Activity. All Im trying to do right now is post the itemName in each cell. If you guys need the logcat, just say so and I'll post it. Any other details needed too.
This is the code for my Activity with a recyclerView with just an ImageView and a TextView in each cell.:
class EssentialsActivity : AppCompatActivity() {
var category: String? = null
val realmtypeFunctions = RealmTypeFunctions()
var realmResults: RealmResults<ChattRItem>? = null
var chattRItemList = mutableListOf<ChattRItem>()
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_essentials)
//init realm
Realm.init(this)
category = "People"
recyclerView_Essentials.setBackgroundColor(Color.CYAN)
recyclerView_Essentials.layoutManager = GridLayoutManager(this, 3)
// AsyncTask.execute {
category?.let {
loadFromRealm(it)
}
// }
this.runOnUiThread {
recyclerView_Essentials.adapter = EssentialsAdapter(chattRItemList)
}
}
override fun onCreateOptionsMenu(menu: Menu?): Boolean {
val inflater = menuInflater
inflater.inflate(R.menu.categories, menu )
return super.onCreateOptionsMenu(menu)
}
override fun onOptionsItemSelected(item: MenuItem?): Boolean {
val intent: Intent?
intent = Intent(this, AddItemActivity::class.java)
intent.putExtra("category", category)
startActivity(intent)
// when (item?.itemId) {
// R.id.essentials_menu_item -> {
// intent = Intent(this, EssentialsActivity::class.java)
// startActivity(intent)
// }
// R.id.addItem_menu_item -> {
// intent = Intent(this, AddItemActivity::class.java)
// startActivity(intent)
// }
// else -> return false
// }
return super.onOptionsItemSelected(item)
}
private fun loadFromRealm(category: String){
val realm = Realm.getDefaultInstance()
try {
val query: RealmQuery<ChattRItem>? = realm.where(ChattRItem::class.java).equalTo("itemCategory", category)
val result: RealmResults<ChattRItem>? = query?.findAll()
result?.let {
for (i in it) {
println(i.itemName)
chattRItemList.add(i)
}
println(chattRItemList.count())
}
} finally {
realm.close()
}
}
}
class EssentialsAdapter(private val chattRItemList: List<ChattRItem>): RecyclerView.Adapter<CustomViewHolder>(){
//realm class variable here to be displayed
/* var essentials = array of realm essential item */
// var essentialsActivity = EssentialsActivity()
//number of items
override fun getItemCount(): Int {
// return 12 //return realm items count
return this.chattRItemList.size
}
override fun onBindViewHolder(holder: CustomViewHolder, position: Int) {
// holder.itemView.textView_essentials_name.text = "Essentials Item"
val chattRItem = chattRItemList.get(position)
// holder.itemView.textView_essentials_name.text = chattRItem.itemName
holder.bind(chattRItem)
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): CustomViewHolder{
// how do we create a cell view
val layoutInflater = LayoutInflater.from(parent.context)
val cellForRow = layoutInflater.inflate(R.layout.essentials_cells_layout, parent, false)
return CustomViewHolder(view = cellForRow)
}
}
class CustomViewHolder(view: View): RecyclerView.ViewHolder(view) {
fun bind(chattRitem: ChattRItem) {
itemView.textView_essentials_name.text = chattRitem.itemName
}
}
So basically I figured it out. This was not the right error from LogCat. There was another set of errors from Logcat many lines above this. The error was the result list was a #Realm object. My recyclerView was asking for a non RealmClass object. So i had to make a similar object except not a RealmClass.
#RealmClass
open class ChattRItem: RealmModel {
#PrimaryKey var itemId: String = ""
var itemName: String = ""
var itemCategory: String = ""
var itemImageFileName: String = ""
var itemAudioFileName: String = ""
}
class ChattRBoxItems(val itemId: String, val itemName: String, val itemCategory: String, val itemImageFileName: String, val itemAudioFileName: String)
then I mapped the result into this new class then applied it to my recyclerView.

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