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how to make pagination with so that there is less code in the fragment without paging 3

I parse NewsApi and use clean architecture also ListAdapter.
I need to do "pagination" so that In my fragment be less code.
By use abstract class or extension file, but I don't know, how to do it.
Also I don't understand how to do addAll method in ListAdapter, so that past items don't disappear.
How I understand paging 3 not compatible with clean architecture.
I have tried do the follow:https://coderoad.ru/51433106/kotlin-RecyclerView-%D0%BD%D1%83%D0%BC%D0%B5%D1%80%D0%B0%D1%86%D0%B8%D1%8F-%D1%81%D1%82%D1%80%D0%B0%D0%BD%D0%B8%D1%86
but it failed.
Also the follow:
fun pagination(viewModel: EverythingViewModel): RecyclerView.OnScrollListener {
return object : RecyclerView.OnScrollListener() {
override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
super.onScrolled(recyclerView, dx, dy)
if (dy > 0) {
val layoutManager = recyclerView.layoutManager as LinearLayoutManager
val firstVisibleItemPosition = layoutManager.findFirstVisibleItemPosition()
val visibleItemCount = layoutManager.childCount
val totalItemCount = layoutManager.itemCount
if (visibleItemCount + firstVisibleItemPosition >= totalItemCount) {
viewModel.page++
viewModel.getEverything()
}
}
}
}
}
Also failed
If you need more details write me in the comments

Access data from RecyclerView Item when visible on screen

I am trying to access the underlying data from a recyclerview item when it scrolls onto the screen.
I am using onAttachedToRecyclerView() inside my Adapter class. Then get the data within onScrolled().
Here is what I have so far:
override fun onAttachedToRecyclerView(recyclerView: RecyclerView) {
super.onAttachedToRecyclerView(recyclerView)
val manager = recyclerView.layoutManager
Log.i("ProductAdapter","$manager")
if (manager is StaggeredGridLayoutManager) {
val slm: StaggeredGridLayoutManager = manager
recyclerView.addOnScrollListener(object : RecyclerView.OnScrollListener() {
override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
super.onScrolled(recyclerView, dx, dy)
val firstVisibleItemPosition: Int
val firstVisibleItemPositions =
slm.findFirstVisibleItemPositions(null)
firstVisibleItemPosition = firstVisibleItemPositions[0]
if (firstVisibleItemPosition > -1) {
val item = getItem(firstVisibleItemPosition))
// do stuff with item data
}
}
})
}else{
Log.e("ProductAdapter","error")
}
}
when I set val manager = recyclerView.layoutManager, manager ends up being null. So the first if check never passes. My code is referencing this answer from another question.
Any ideas on how to fix this?

In my Fragment I was setting the adapter for the recyclerview one line before setting the layout manager.
Code before:
recyclerViewProducts.apply {
this.adapter = productAdapter
layoutManager = staggeredGridLayoutManager
itemAnimator?.changeDuration = 0
}
Code after:
recyclerViewProducts.apply {
layoutManager = staggeredGridLayoutManager
this.adapter = productAdapter
itemAnimator?.changeDuration = 0
}
Thanks to cactustictacs

Scrolling a RecyclerView inside another RecyclerView automatically not working correctly

So am having this recyclerview which will contain holders of multiple types one of which could be a scrollable horizontal list of edge to edge images, that are being scrolled automatically and have a current item indicator. so for this i used a viewholder which will itself contain another recyclerview and a dots indicator( which itself is another recycler view, so basically recyclerview = a list of vh , where one of the vh = 2 horizontal recyclerview).
title
[A,B,C,D...]
[+ ---]
title
[A,B,C,D...]
[+ --]
title
[A,B,C,D...]
[+ --]
title
[A,B,C,D...]
[+ --]
My innermost recylerview of horizontal images is created something like this:
class ImageAdapter : RecyclerView.Adapter<ImageVH>() {
var imageResList = mutableListOf<Int>()
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) = ImageVH(parent, viewType)
override fun onBindViewHolder(holder: ImageVH, pos: Int)
= holder.bindData(imageResList[pos % imageResList.size])
override fun getItemCount() = Int.MAX_VALUE
}
class ImageVH(v: View) : RecyclerView.ViewHolder(v) {
constructor(parent: ViewGroup, viewtype: Int) : this(
LayoutInflater.from(parent.context).inflate(R.layout.item_image, parent, false)
)
fun bindData(imageRes: Int) {
Glide.with(itemView.context).load("").error(imageRes).into(itemView.ivImage)
}
}
it is basically fooling the adapter to think as if i have a million images but will actually have just a few images. this creates an impression of circular scroll.
Next i will need something to change the dots indicator of the second recyclerview. for this i went into the parent of this recyclerview and attached an onScrollListener . The onScrollListener gives me 2 function: onScrolled and onScrollStateChanged.
with onScrolled , i determine when to change the next dots recyclerview's state to show the new dot. i do this via linear layout manager. when it gives findFirstCompletelyVisibleItemPosition as positive number .
with onScrollStateChanged(), i run a kind of recursion, where whenever i get the state as SCROLL_STATE_IDLE, I post a handler to scroll the recyclerview to next item after 2 seconds. after 2 seconds, it will automatically smooth scroll and again fire the same event, causing the handler to fire the same action again.
so the code looks something like this:
data class Rails(val title: String, val images: MutableList<Int>,val autoscroll:Boolean =false)
class RailsAdapter : RecyclerView.Adapter<RailVH>() {
var railsList = mutableListOf<Rails>()
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int) = RailVH(parent, viewType)
override fun onBindViewHolder(holder: RailVH, pos: Int) = holder.bindData(railsList[pos])
override fun getItemCount() = railsList.size
}
class RailVH(v: View) : RecyclerView.ViewHolder(v) {
constructor(parent: ViewGroup, viewtype: Int) : this(
LayoutInflater.from(parent.context).inflate(R.layout.item_rails, parent, false)
)
private var autoscrollImages = false
fun bindData(rails: Rails) {
autoscrollImages = rails.autoscroll
with(itemView) {
tvTitle?.text = rails.title
rvImagers?.apply {
adapter = ImageAdapter().also {
it.imageResList = rails.images
it.notifyDataSetChanged()
}
PagerSnapHelper().attachToRecyclerView(this)
isNestedScrollingEnabled = false
onFlingListener = null
addOnScrollListener(onScrollListener)
}
}
if(autoscrollImages){
bannerChangerHandler.postDelayed(bannerChangerRunnable,bannerChangerDelayMilllis)
}
}
private val onScrollListener = object : RecyclerView.OnScrollListener() {
override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
//super.onScrolled(recyclerView, dx, dy)
val bannerLLManager = itemView.rvImagers?.layoutManager as? LinearLayoutManager
bannerLLManager?.let { linearLayoutManager ->
val bannerCurrentPos = linearLayoutManager.findFirstCompletelyVisibleItemPosition()
if (bannerCurrentPos >= 0) {
val rvDotsDataListSize = 5
val positionInRange = bannerCurrentPos % rvDotsDataListSize
Toast.makeText(
itemView.context,
"highlight dot #$positionInRange",
Toast.LENGTH_SHORT
).show()
}
}
}
override fun onScrollStateChanged(recyclerView: RecyclerView, newState: Int) {
//super.onScrollStateChanged(recyclerView, newState)
when (newState) {
RecyclerView.SCROLL_STATE_IDLE -> {
if(autoscrollImages){
Log.e(">>a>>", "RecyclerView.SCROLL_STATE_IDLE!")
bannerChangerHandler.postDelayed(bannerChangerRunnable, bannerChangerDelayMilllis
)
}
}
RecyclerView.SCROLL_STATE_DRAGGING -> {
Log.e(">>a>>", "RecyclerView.SCROLL_STATE_DRAGGING!")
bannerChangerHandler.removeCallbacks(bannerChangerRunnable)
}
else -> {
}
}
}
}
private val bannerChangerHandler: Handler = Handler()
private val bannerChangerRunnable = Runnable {
itemView.rvImagers?.apply {
val bannerManager = layoutManager as? LinearLayoutManager
bannerManager?.let {
val bannerCurrentPos = it.findFirstCompletelyVisibleItemPosition()
smoothScrollToPosition(bannerCurrentPos + 1)
}
}
}
private var bannerChangerDelayMilllis = 2000L
}
for brevity, assume whenever the toast is occuring, its going to scroll the 2nd dots indicator recyclerview .
This all seems to work in principle, but after sometimes the handler seems to fire twice or thrice , causing bad ux. sometimes it even goes berserks and stops showing any logs or anything and just makes the rails run infinetely very fast, like handler firing an autoscroll runner every millisecond.
handlers firing 2-3 times
So any help with this? i am assuming something is wrong at the implementation level, like firing handler events could be handled better?
Update:
thanks to #ADM , I got this working. I tweaked it as per my requirements, and had to forgo of circular scroll support in the reverse direction, but the given solution was enough to answer my query. thanks!

Handler is not an issue here its the Runnable. you are using and posting same Runnable each time thats why its getting piled up . You can not remove the previous call because you do not have a Tag or token to this delayed call . take a look at some of Handler's method like sendMessageDelayed these might help .
After giving it some thought i think you can move the Auto scroll part to SnapHelper. Not a full prove solution but i think it will work. You might have to put few checks in SnapHelper . Give it a try and let me know . i haven't tested it.
class AutoPagedSnapHelper(private var autoScrollInterval: Long) : PagerSnapHelper() {
private var recyclerView: RecyclerView? = null
private var currentPage = 0
private var isHold = false
private val autoScrollRunnable = Runnable {
recyclerView?.let {
if (recyclerView?.scrollState != RecyclerView.SCROLL_STATE_DRAGGING && !isHold) {
if (it.adapter != null) {
val lastPageIndex = (recyclerView?.adapter!!.itemCount - 1)
var nextIndex: Int
nextIndex = currentPage + 1
if (currentPage == lastPageIndex) {
nextIndex = 0
}
it.post {
val linearSmoothScroller = object : LinearSmoothScroller(recyclerView?.context) {
override fun calculateSpeedPerPixel(displayMetrics: DisplayMetrics): Float {
return MILLISECONDS_PER_INCH / displayMetrics.densityDpi
}
}
linearSmoothScroller.targetPosition = nextIndex
(recyclerView?.layoutManager as LinearLayoutManager).startSmoothScroll(linearSmoothScroller)
}
}
} else {
postNextPage()
}
}
}
override fun attachToRecyclerView(recyclerView: RecyclerView?) {
super.attachToRecyclerView(recyclerView)
if (this.recyclerView === recyclerView) {
return
}
if (autoScrollInterval != 0L) {
this.recyclerView = recyclerView
this.recyclerView?.addOnScrollListener(object : RecyclerView.OnScrollListener() {
override fun onScrollStateChanged(recyclerView: RecyclerView, newState: Int) {
super.onScrollStateChanged(recyclerView, newState)
if (newState == RecyclerView.SCROLL_STATE_IDLE || newState == RecyclerView.SCROLL_STATE_SETTLING) {
val itemPosition = (recyclerView.layoutManager as LinearLayoutManager).findFirstCompletelyVisibleItemPosition()
if (itemPosition != -1) {
currentPage = itemPosition
postNextPage()
}
}
}
})
postNextPage()
recyclerView?.addOnItemTouchListener(object : RecyclerView.OnItemTouchListener {
override fun onInterceptTouchEvent(rv: RecyclerView, event: MotionEvent): Boolean {
when (event.action) {
MotionEvent.ACTION_DOWN -> {
isHold = true
}
MotionEvent.ACTION_CANCEL, MotionEvent.ACTION_UP, MotionEvent.ACTION_POINTER_UP -> {
isHold = false
}
}
return false
}
override fun onTouchEvent(rv: RecyclerView, event: MotionEvent) {}
override fun onRequestDisallowInterceptTouchEvent(disallowIntercept: Boolean) {}
})
}
}
fun postNextPage() {
recyclerView?.handler?.removeCallbacks(autoScrollRunnable)
recyclerView?.postDelayed(autoScrollRunnable, autoScrollInterval)
}
companion object {
private const val MILLISECONDS_PER_INCH = 75f //default is 25f (bigger = slower)
}
}
This should take care of auto change page. You do not have to use scrollListener in Adapter. Give it a try.

Kotlin - Scroll Detection issue in Recyclerview

Using below code to check that whether RecyclerView reached to bottom or not..
Means Checking that last item of the Recyclerview is visible or not..
For that I have googled and added Scroll listener in Recyclerview.
Using below code:
MyRecyclerView.addOnScrollListener(object : RecyclerView.OnScrollListener() {
override fun onScrollStateChanged(recyclerView: RecyclerView, newState: Int) {
super.onScrollStateChanged(recyclerView, newState)
}
override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
super.onScrolled(recyclerView, dx, dy)
if (!MyRecyclerView.canScrollVertically(1)) {
Toast.makeText(mContext, "Last", Toast.LENGTH_LONG).show();
}
}
})
Here, I am trying to check that Recyclerview reached to bottom or not.
Toast is not displaying when I scroll recyclerview to the bottom.
But, Toast displayed suddenly when items in the recyclerview binds first time. It should toast only when user scroll up to the bottom of the Recyclerview.
What might be the issue ?
Please guide. Thanks.

I think, using RecyclerView.LayoutManager api will better suit your needs.
You can check LinearLayoutManager::findLastCompletelyVisibleItemPosition or findLastVisibleItemPosition method in your RecyclerView.OnScrollListener

rvPlayers?.addOnScrollListener(object : RecyclerView.OnScrollListener() {
override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
super.onScrolled(recyclerView, dx, dy)
if (dy > 0) {
if (isLastVisable()) {
//code here
}
}
}
})
private fun isLastVisable(): Boolean {
val layoutManager = rvPlayers.layoutManager as LinearLayoutManager
val pos = layoutManager.findLastCompletelyVisibleItemPosition()
val numItems = adapter.itemCount
return (pos >= numItems - 1)
}

Android OnScrollListener doesnt work correctly

I am trying to add an infinite scroll to my Android Application but the onScrolled method doesnt work correctly I think so.
It will be called only once if I call the addOnScrollListener. But I think it should be called every time the RecyclerView has been scrolled.
linearLayoutManager = LinearLayoutManager(this)
recyclerViewNeuheiten.layoutManager = linearLayoutManager//LinearLayoutManager(this)
recyclerViewHistory.layoutManager = LinearLayoutManager(this)
recyclerViewBestSeller.layoutManager = LinearLayoutManager(this)
recyclerViewFavorites.layoutManager = LinearLayoutManager(this)
recyclerViewNeuheiten.adapter = neuheitenAdapter
recyclerViewHistory.adapter = historyAdapter
recyclerViewBestSeller.adapter = bestsellerAdapter
recyclerViewFavorites.adapter = favoriteAdapter
//setRecyclerViewScrollListener()
setRecyclerViewScrollListener()
private fun setRecyclerViewScrollListener() {
Log.v("scroll", "set listener")
recyclerViewNeuheiten.addOnScrollListener(object : RecyclerView.OnScrollListener() {
override fun onScrollStateChanged(recyclerView: RecyclerView, newState: Int) {
super.onScrollStateChanged(recyclerView, newState)
Log.v("scroll", "onScrollStateChanged newState $newState")
}
override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
Log.v("scroll", "onScrolled !!!!!")
super.onScrolled(recyclerView, dx, dy)
val currentItem = recyclerView.layoutManager!!.childCount
val totalItemCount = recyclerView.layoutManager!!.itemCount
Log.v("scroll", "currentItem $currentItem")
Log.v("scroll", "totalItemCount $totalItemCount")
Log.v("scroll", "lastVisibleItemPosition $lastVisibleItemPosition")
Log.v("scroll", "scroll out items ${linearLayoutManager.findFirstVisibleItemPosition()}")
}
})
}

I found the problem. I am using my RecyclerView inside a NestedScrollView. The onScrolled method triggers each scroll without a ScrollView.