Develop Reference

Implementing Viewpager2 in a fragment with Recycler view

I'm trying to implement viewpager2 in a fragment which shows a list of notes with Recycler View. I tried different solutions but I'm unable to figure it out.
Here is my fragment_notes_list.xml :
<androidx.recyclerview.widget.RecyclerView
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/notes_recycler_view"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
list_item_notes.xml used to display recycler view viewholder:
<androidx.cardview.widget.CardView
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:card_view="http://schemas.android.com/apk/res-auto"
android:id="#+id/card_pertanyaan"
android:layout_width="match_parent"
android:layout_height="96dp"
android:layout_marginLeft="16dp"
android:layout_marginTop="12dp"
android:layout_marginRight="16dp"
android:clickable="true"
android:foreground="?selectableItemBackground"
card_view:cardBackgroundColor="#595959"
card_view:cardCornerRadius="8dp"
card_view:contentPadding="10dp">
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/linearLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<TextView
android:id="#+id/notes_title"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginTop="16dp"
android:layout_marginEnd="8dp"
android:text="Title"
android:textColor="#color/white"
app:layout_constraintBottom_toTopOf="#+id/notes_body"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_chainStyle="packed" />
<TextView
android:id="#+id/notes_body"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:layout_marginEnd="8dp"
android:textColor="#color/white"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/notes_title" />
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.cardview.widget.CardView>
Relevant snippets from fragment class NotesListFragment.kt :
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
val view = inflater.inflate(R.layout.fragment_notes_list, container, false)
notesRecyclerView =
view.findViewById(R.id.notes_recycler_view) as RecyclerView
registerForContextMenu(notesRecyclerView)
notesRecyclerView.layoutManager = LinearLayoutManager(context)
notesRecyclerView.adapter = adapter
return view
}
private inner class ScreenSlidePagerAdapter(fa: Fragment) : FragmentStateAdapter(fa) {
override fun getItemCount(): Int = NUM_PAGES
override fun createFragment(position: Int): Fragment {
return if (position == 0) {
NotesListFragment()
} else {
CalenderFragment()
}
}
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
notesListViewModel.notesListLiveData.observe(
viewLifecycleOwner,
Observer { notes ->
notes?.let {
Log.i(TAG, "got notes")
updateUI(notes)
}
})
}
private inner class NotesAdapter(var notes: List<Notes>) : RecyclerView.Adapter<NotesHolder>() {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): NotesHolder {
val view = layoutInflater.inflate(R.layout.list_item_notes, parent, false)
/* viewPager = view.findViewById(R.id.pager)
val pagerAdapter = ScreenSlidePagerAdapter(this#NotesListFragment)
viewPager.adapter = pagerAdapter */
return NotesHolder(view)
}
override fun getItemCount() = notes.size
override fun onBindViewHolder(holder: NotesHolder, position: Int) {
val note = notes[position]
holder.bind(note)
}
}
I'm confused should I add ViewPager2 with FrameLayout in list_item_notes.xml?
But then how can I implement ScreenSliderPagerAdapter for it?

I assume you would like to have 2 fragments: list and calendar and thats why you need to implement ViewPager2. Your NotesListFragment looks good. You have recyclerview with notes there, but what you want now is to provide list of NotesListFragment and CalendarFragment which will be scrollable in left/right direction. First, extract ScreenSlidePagerAdapter outside of your fragment code. Next you have to add ViewPager2 to your parent activity/fragment
<androidx.viewpager2.widget.ViewPager2
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/pager"
android:layout_width="match_parent"
android:layout_height="match_parent" />
And then in your parent activity/fragment pair it with adapter like this way:
val viewPager = findViewById(R.id.pager)
val pagerAdapter = ScreenSlidePagerAdapter(this)
viewPager.adapter = pagerAdapter
You can read more about this in official docs: https://developer.android.com/training/animation/screen-slide-2

I had tried implementing ViewPager in Main Activity earlier also. But this way i cannot close viewpager fragments since they are always visible. How do I get around this?
here is my main activity after the changes you suggested:
class MainActivity : AppCompatActivity(),
NotesListFragment.Callbacks {
private lateinit var viewPager: ViewPager2
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
viewPager = findViewById(R.id.pager)
val pagerAdapter = ScreenSlidePagerAdapter(this)
viewPager.adapter = pagerAdapter
}
override fun onNotesSelected(notesId: UUID) {
val fragment = NotesFragment.newInstance(notesId)
supportFragmentManager
.beginTransaction()
.replace(R.id.fragment_container, fragment)
.addToBackStack(null)
.commit()
}
fun onNotesDeleted(notes: Notes) {
val fragment = NotesListFragment()
supportFragmentManager
.beginTransaction()
.replace(R.id.fragment_container, fragment)
.commit()
Toast.makeText(this, "Note Deleted", Toast.LENGTH_SHORT).show()
}
mainactivity.xml:
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/fragment_container"
android:layout_width="match_parent"
android:layout_height="match_parent">
<androidx.viewpager2.widget.ViewPager2
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/pager"/>
</FrameLayout>
here are some screenshots,
https://drive.google.com/drive/folders/13ITZqcaeDeydCe0tW2Iu7VoSGSZnrlkg?usp=sharing

Solved the problem.
Since, I was unable to add Viewpager with recycler view of NotesListFragment, I made another Parent Fragment with viewpager and put NotesListFragment inside it.

E/RecyclerView: No adapter attached; skipping layout Kotlin Android

I have created a fragment and inside that fragment I have a recyclerview but when my fragment is loaded nothing shows and it give me this error "E/RecyclerView: No adapter attached; skipping layout". Below is the code for the adapter and fragment class, any help would be appreciated
Adapter Class:
class ViewAllRecipeAdapter(private val newList: ArrayList<Recipes>) :
RecyclerView.Adapter<ViewAllRecipeAdapter.MyViewHolder>() {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyViewHolder {
val itemView = LayoutInflater.from(parent.context).inflate(R.layout.view_all_recipe_item, parent, false)
return MyViewHolder(itemView)
}
override fun onBindViewHolder(holder: MyViewHolder, position: Int) {
val currentItem = newList[position]
holder.recipeName.text = currentItem.recipeName
holder.recipeDesc.text = currentItem.recipeDescription
}
override fun getItemCount(): Int {
return newList.size
}
class MyViewHolder(itemview: View) : RecyclerView.ViewHolder(itemview) {
val recipeName: TextView
val recipeDesc: TextView
init {
recipeName = itemView.findViewById<View>(R.id.recipe_name) as TextView
recipeDesc = itemView.findViewById<View>(R.id.recipe_description) as TextView
}
}
}
Fragment Class:
class ViewAllMyRecipesFragment : Fragment() {
private lateinit var recyclerview: RecyclerView
private lateinit var recipeData: ArrayList<Recipes>
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
val view: View = inflater.inflate(R.layout.fragment_view_all_my_recipes, container, false)
recipeData = dummygenerator(10)
recyclerview = view.findViewById<RecyclerView>(R.id.recycler_view_all_recipes)
recyclerview.adapter = ViewAllRecipeAdapter(recipeData)
recyclerview.layoutManager = LinearLayoutManager(view.context)
recyclerview.setHasFixedSize(true)
// Inflate the layout for this fragment
return view
}
private fun dummygenerator(size: Int) : ArrayList<Recipes>{
val list = ArrayList<Recipes>()
for(i in 0 until size) {
val drawable = when (i % 3) {
0 -> "recipeName " +i
1 -> "recipeDescription " + i
else -> "Else " +i
}
val item = Recipes("title $i", "body")
list += item
}
return list
}
}
fragment_view_all_my_recipes.xml
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context=".ui.recipe.ViewAllMyRecipesFragment">
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/recycler_view_all_recipes"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:listitem="#layout/view_all_recipe_item" />
</androidx.constraintlayout.widget.ConstraintLayout>
view_all_recipe_item.xml
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<ImageView
android:id="#+id/recipe_image"
android:layout_width="80dp"
android:layout_height="80dp"
android:layout_marginEnd="331dp"
android:layout_marginBottom="651dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
tools:srcCompat="#tools:sample/avatars" />
<TextView
android:id="#+id/recipe_name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="25dp"
android:text="TextView"
android:textStyle="bold"
android:textSize="18sp"
app:layout_constraintStart_toEndOf="#+id/recipe_image"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="#+id/recipe_description"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="32dp"
android:layout_marginTop="10dp"
android:text="TextView"
app:layout_constraintStart_toEndOf="#+id/recipe_image"
app:layout_constraintTop_toBottomOf="#+id/recipe_name" />
</androidx.constraintlayout.widget.ConstraintLayout>

Try moving all onCreateView logic to onViewCreated and
recyclerview.layoutManager = LinearLayoutManager(requireActivity())
recyclerview.adapter = ViewAllRecipeAdapter(recipeData)
because sometimes it causes problem when layoutManager is after adapter.

Android recyclerView problem - multi-layer scrolling content?

I am brand new in Android/kotlin development. I created my very first app with a recyclerView to display the folders and files of the phone. I put the recyclerView into a segment, created my data structure and adapter. Assembled together. It works - or seems to work. But the problem is that when I try to scroll the list, the initial state remains "ther" and the list content starts to scroll. Like it was two different layers. I have no clue where to find the problem. Never heard about such a bug like this. Please give me advice, some keywords where to dig and find the solution. Thanks!
class BrowseFileFragment : Fragment() {
private lateinit var attachedCtx : Context
override fun onAttach(context: Context) {
super.onAttach(context)
this.attachedCtx = context
}
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,savedInstanceState: Bundle?): View?
{
var view : View = inflater.inflate(R.layout.fragment_browse_file, container, false)
val modelFactory = FileBrowseModelFactory()
val data = modelFactory.create()
bindModelToView(data, view)
return view
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
}
private fun bindModelToView(data: BrowseSettings, view: View)
{
var adapter = MyFileAdapter(data.FoldersAndFiles, this.attachedCtx)
var recyclerView = view.findViewById<RecyclerView>(R.id.fileItemView)
var linearLayoutManager = LinearLayoutManager(this.attachedCtx)
recyclerView.layoutManager = linearLayoutManager
recyclerView.adapter = adapter
var folderLabel = view.findViewById<TextView>(R.id.folderName)
folderLabel.text = data.CurrentFolder
}
}
The segment layout
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".BrowseFileFragment">
<TextView
android:id="#+id/folderName"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="5dp"
android:text="#string/hello_first_fragment"
android:textAlignment="viewStart"
android:textAppearance="#style/TextAppearance.AppCompat.Display1"
android:textStyle="bold"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/fileItemView"
android:layout_width="match_parent"
app:layout_constrainedHeight="true"
android:layout_height="0dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="#+id/folderName"
app:layout_constraintStart_toStartOf="#+id/folderName"
app:layout_constraintTop_toBottomOf="#+id/folderName" />
</androidx.constraintlayout.widget.ConstraintLayout>
The list line layout
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="60dp">
<TextView
android:background="#color/cardview_shadow_start_color"
android:id="#+id/itemName"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintBottom_toTopOf="parent"
android:padding="5dp"
android:textSize="30dp"
android:textStyle="bold" />
</androidx.constraintlayout.widget.ConstraintLayout>
And finally my adapter:
class MyFileAdapter(private val items: List<FileItem>, private val context: Context)
: RecyclerView.Adapter<MyFileAdapter.MyViewHolder>()
{
class MyViewHolder (itemView: View) :RecyclerView.ViewHolder(itemView), View.OnClickListener {
init {
itemView.setOnClickListener(this)
}
fun bindItem(f: FileItem) {
var name: TextView = itemView.findViewById(R.id.itemName) as TextView
name.text = f.Name
}
}
override fun getItemCount() = items.size
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyViewHolder {
val view = LayoutInflater
.from(context)
.inflate(R.layout.recyclerview_filteitem_row, parent, false)
return MyViewHolder(view)
}
override fun onBindViewHolder(holder: MyViewHolder, position: Int) {
var item = items\[position\]
holder!!.bindItem( item )
}
}

It found out that as the whole list view is saved as a segment, this segment loads "automatically" and was loaded programatically also, and the two "loads" causes this thing. :( Thanks for your time guys.

Creating a PagerView inside a RecyclerView

I am trying to make a PagerView inside a RecyclerView using androidx widgets, here is my code:
ManageCategories.jt (Fragment)
class ManageCategories : Fragment() {
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
//TODO make json for categories
val root = inflater.inflate(R.layout.fragment_manage_categories, container, false)
val array = arrayOf("this", "is", "a", "test")
val viewAdapter = CategoryRecyclerAdapter(array)
val templateList = root.findViewById<RecyclerView>(R.id.template_manage_category)
val itemDecoration: RecyclerView.ItemDecoration = DividerItemDecoration(context, DividerItemDecoration.VERTICAL)
templateList.addItemDecoration(itemDecoration)
templateList.adapter = viewAdapter
return root
}
}
fragment_manage_categories.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".ui.templates.templates.ManageTemplates">
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/template_manage_category"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layoutManager="LinearLayoutManager" />
</androidx.constraintlayout.widget.ConstraintLayout>
The fragment gets inflates and sets a RecyclerAdapter
CategoryRecyclerAdapter.kt
class CategoryRecyclerAdapter(private val myDataset: Array<String>) :
RecyclerView.Adapter<CategoryViewHolder>() {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): CategoryViewHolder {
val layout = LayoutInflater.from(parent.context).inflate(R.layout.list_category, parent, false)
return CategoryViewHolder(layout)
}
override fun onBindViewHolder(holder: CategoryViewHolder, position: Int) {
holder.itemView.setOnClickListener {
when (position) {
0 -> {
Log.d("TEXT", "backup")
}
}
}
//TODO uncomment holder.textView.text = myDataset[position]
}
override fun getItemCount() = myDataset.size
}
CategoryViewHolder.kt
class CategoryViewHolder(v: View) : RecyclerView.ViewHolder(v) {
init {
val vp = v.findViewById<ViewPager>(R.id.category_pager)
val pagerAdapter = CategoryPagerAdapter()
vp.adapter = pagerAdapter
}
}
list_category.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:background="?android:attr/selectableItemBackground" >
<androidx.viewpager.widget.ViewPager
android:id="#+id/category_pager"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</LinearLayout>
The RecyclerAdapter inflates each recycled view (4 times) with some dummy data ("this" "is" "a" "test")
when the ViewHolder is called it initializes the PagerView and sets its adapter (I have tried to do this in a ViewHolder and the RecyclerAdapters onCreateViewHolder() method but it made no difference)
CategoryPagerAdapter.kt
class CategoryPagerAdapter: PagerAdapter() {
override fun isViewFromObject(view: View, `object`: Any): Boolean {
return view === `object`
}
override fun getCount() = 2
override fun instantiateItem(collection: ViewGroup, position: Int): ViewGroup {
val view: CategoryModel = CategoryModel.values().get(position)
val inflater = LayoutInflater.from(collection.context)
val layout = inflater.inflate(view.layoutResId, collection, false) as ViewGroup
collection.addView(layout)
return layout
}
override fun destroyItem(collection: ViewGroup, position: Int, view: Any) {
collection.removeView(view as View?)
}
}
CategoryModel.kt
enum class CategoryModel(val layoutResId: Int) {
TEXT(R.layout.category_list_item),
BUTTONS(R.layout.button_pager);
}
category_list_item.kt
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:background="?android:attr/selectableItemBackground" >
<TextView
android:id="#+id/text_item"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="hello"
android:textSize="15sp"
android:padding="15dp" />
</LinearLayout>
button_pager.xml
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:background="?android:attr/selectableItemBackground" >
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="world"
android:textSize="15sp"
android:padding="15dp" />
</LinearLayout>
The PagerAdapter then begins to inflate views with static text in place of RecyclerView Views with 2 PagerViews both of which are holding dummy text ("hello" "world"). This doesn't appear to work, I cant figure out why.
I have put the code through the debugger
the Recycler is being inflated 4 times
the Pager is being inflated 2 times with the correct layout files each time
yet I can't see any text, and when I try to findViewById for the TextViews the debugger returns false.
Whats going on? why can't I see the text?
EDIT:
To test I decided to remove the recycler so that only the pager was in use:
ManageCategories.jt (Fragment)
class ManageCategories : Fragment() {
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
//TODO make json for categories
val root = inflater.inflate(R.layout.list_category, container, false)
val pagerAdapter = CategoryPagerAdapter()
val pager: ViewPager = root.findViewById(R.id.category_pager)
pager.adapter = pagerAdapter
return root
}
}
This worked as expected and the Pager layout worked fine. In a seperate test I removed the Pager layout and that also worked fine. I just can't get the two to work together.
My current working theory is that I am trying to inflate the view within CategoryViewHolder through CategoryPagerAdapter something I found out about RecyclerView was that it doesn't like inflating views within its ViewHolder. I just don't know where to put it.
EDIT2:
I have moved the code that initializes CategoryPagerAdapter into onCreateViewHolder and/or onBindViewHolder method of CategoryRecyclerAdapter.
After further investigation I have found that instantiateItem() is returning a proper ViewGroup of inflated views insideCategoryPagerAdapter. However, for whatever reason when I try to inspect the object/views outside of the class(CategoryRecyclerAdapter) pagerAdapter they appear to be emtpy. I am confident that when I can figure out why it is getting null that the functionality will be working as expected, but I can't figure out why. Please help.
EDIT3:
I figured that since the pager was inflating the views, according to the values in the debugger. But then when inspecting the pager inside the recycler that views were no longer present, naturally I thought they were using different inflaters.
I compared the two inflaters used in the Logs and they are both the same object, so its not that.

I managed to get the functionality by using a ViewPager2 since ViewPager is no longer actively being worked on;
class CategoryPagerAdapter(private val model: Array<CategoryModel>): RecyclerView.Adapter<CategoryPagerViewHolder>() {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): CategoryPagerViewHolder {
val view = model[viewType].layoutResId
val layout = LayoutInflater.from(parent.context).inflate(view, parent, false)
return CategoryPagerViewHolder(layout)
}
override fun getItemViewType(position: Int): Int = position
override fun getItemCount() = model.size
override fun onBindViewHolder(holder: CategoryPagerViewHolder, position: Int) {
holder.itemView.setOnClickListener {
when (position) {
0 -> {
Log.d("TEXT", "backup")
}
}
}
}
}
class CategoryPagerViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView)
Here is a barely working version of the code. Text isn't properly being updated yet.

Kotlin Android Recycler view inside Fragment with Bottom Navigation not working

I am trying to develop social networking app which uses Android Jetpack Libraries but while using Navigation Component to use bottom navigation to navigate through fragments inside an activity , This Adapter throws an error at LayoutInflator() which causes app to crash
Can anyone help me through this:
My Adapter Class:
class FeedAdapter : PagedListAdapter<feed,FeedAdapter.ViewHolder>(FeedDiffCallBack()){
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
val userPost = LayoutInflater.from(parent.context)
.inflate(R.layout.feedrow,parent,false)
return ViewHolder(userPost)
}
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
val feedItem = getItem(position)
if(feedItem != null){
holder.bind(feedItem)
}
}
class ViewHolder(itemView:View):RecyclerView.ViewHolder(itemView) {
//Retrieve data
private val username:TextView = itemView.post_name
private val userPic:ImageView = itemView.feedImage1
private val location:TextView = itemView.postLocation
private val time:TextView = itemView.postTime
private val post:ImageView = itemView.postImage
fun bind(feed: feed) = with(itemView){
//TODO:Bind Data with View
showFeedData(feed)
}
private fun showFeedData(feed: feed) {
username.text = feed.username
userPic.setImageURI(null)
userPic.visibility = View.GONE
location.text = feed.location
time.text = feed.timeStamp.toString()
post.setImageURI(Uri.parse(feed.mUrl))
}
}
}
class FeedDiffCallBack : DiffUtil.ItemCallback<feed>() {
override fun areItemsTheSame(oldItem:feed, newItem: feed): Boolean {
return oldItem?.id == newItem?.id
}
override fun areContentsTheSame(oldItem: feed, newItem: feed): Boolean {
return oldItem == newItem
}
}
Fragment Class:
class FeedFragment : Fragment() {
companion object {
fun newInstance() = FeedFragment()
}
private lateinit var viewModel: FeedViewModel
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
val view = inflater.inflate(R.layout.feed_fragment, container, false)
val context = getContext() ?: return view
val factory = InjectorUtils.provideViewModelFactory(context)
viewModel =
ViewModelProviders.of(this,factory).get(FeedViewModel::class.java)
val adapter = FeedAdapter()
view.findViewById<RecyclerView>(R.id.feedView).adapter = adapter
view.findViewById<RecyclerView>(R.id.feedView).layoutManager =
LinearLayoutManager(MyApplication.getContext())
subscribeUI(adapter)
return view
}
private fun subscribeUI(adapter: FeedAdapter) {
viewModel.showFeed().observe(this, object:Observer<PagedList<feed>>{
override fun onChanged(t: PagedList<feed>?) {
adapter.submitList(t)
adapter.notifyDataSetChanged()
}
})
}
override fun onActivityCreated(savedInstanceState: Bundle?) {
super.onActivityCreated(savedInstanceState)
}
}
feed_row.xml
Individual item for recycler view -->
<RelativeLayout
android:id="#+id/postContainer"
android:layout_margin="10dp"
android:elevation="2dp"
android:background="#drawable/bg_parent_rounded_corner"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<!--TODO:Change to Circle Image View-->
<ImageView
android:id="#+id/profileImage"
android:layout_width="50dp"
android:layout_height="50dp"
android:layout_marginTop="5dp"
android:layout_marginLeft="5dp"
android:adjustViewBounds="true"
android:scaleType="fitCenter"
/>
<LinearLayout
android:id="#+id/postDetail_1"
android:orientation="vertical"
android:layout_marginTop="5dp"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="5dp"
android:layout_marginRight="20dp"
android:layout_alignParentRight="true">
<TextView
android:id="#+id/post_name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
style="#style/LabelStyle"
android:textSize="15sp"
android:fontFamily="#font/sf_pro_display_semibold" />
<LinearLayout
android:id="#+id/postDetail_2"
android:orientation="horizontal"
android:layout_width="wrap_content"
android:layout_height="wrap_content">
<TextView
android:id="#+id/postLocation"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
<TextView
android:id="#+id/postTime"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="120dp" />
</LinearLayout>
</LinearLayout>
<ImageView
android:id="#+id/postImage"
android:layout_height="200dp"
android:layout_width="match_parent"
android:layout_below="#+id/postDetail_1"
android:adjustViewBounds="true"
android:scaleType="fitCenter"
android:layout_marginTop="6dp"
/>
</RelativeLayout>

Your issue might be in this method,
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
val feedItem = getItem(position)
if(feedItem != null){
holder.bind(feedItem)
}
}
Your ViewHolder is using poisition from method parameter which might be inconsistent
See from here,
So, you should change line to this:
val feedItem = getItem(holder.adapterPosition)
instead of
val feedItem = getItem(position)
I hope it resolves the issue.

This might help some one looking for the same Exception to be cleared :
What I did is that my feed_row.xml above is included inside < layout > tags and I changed it in this way , So the exception got cleared:
Before Exception:
<layout xmlns:android="http://schemas.android.com/apk/res/android">
After changing to this Exception cleared:
<layout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools">
I don't know how it works but it did work!!! So Anyone who knows what happens there can explain please!