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RecyclerView data not showing

My ReycyclerView is not showing data, but once i removed .setHasFixedSize(true), then only it will display. However, this causes another problem. On the first time entering the fragment, it works fine, my actionBar is displaying, but on the second time, it somehow overlaps or pushes away my ActionBar.
I guess .sethasFixedSize is necessary but if i keep it, it will not display data. What causes this?
First time entering:
Second time entering (before notifyItemInserted()):
After notifyItemInserted():
fragment.xml:
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/cartItemRv"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</RelativeLayout>
fragment.kt:
onCreateView() {
binding.cartItemRv.layoutManager = LinearLayoutManager(context)
binding.cartItemRv.setHasFixedSize(true)
cartAdapter = CartAdapter(productNameList, productVariationList, cartItemList)
binding.cartItemRv.adapter = cartAdapter
//code for retrieving data from Firebase
cartAdapter.notifyItemInserted(productNameList.size-1)
}
Adapter:
class CartAdapter(...: RecyclerView.Adapter<CartAdapter.CartViewHolder>() {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): CartViewHolder {
val itemView = LayoutInflater.from(parent.context).inflate(R.layout.cart_item, parent, false)
return CartViewHolder(itemView, mListener)
}
override fun onBindViewHolder(holder: CartViewHolder, position: Int) {
...
}
override fun getItemCount(): Int {
return productNameList.size
}
inner class CartViewHolder(itemView: View, listener: onItemClickListener) : RecyclerView.ViewHolder(itemView){
...
}
}

about sethasFixedSize , if the size of your the RecyclerView depends on the adapter's content you have to set the sethasFixedSize vlaue : false
otherwise set it true .
// for depending on adapter
mRecyclerView.setHasFixedSize(false);
// for doesn't depend on adapter
mRecyclerView.setHasFixedSize(true);

add NestedScrollView on the parent of RecyclerView
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<androidx.core.widget.NestedScrollView
android:layout_width="match_parent"
android:layout_height="match_parent">
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/cartItemRv"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:nestedScrollingEnabled="false"/>
</androidx.core.widget.NestedScrollView>
</RelativeLayout>
Then set RecyclerView
cartItemRv.setHasFixedSize(false);

listview items are not showing when i set the height to wrap or match or 0dp, they only show up when i use specific number

my listview has a relative layout parent, it is set to wrap hight and match width, the problem is in the listview height, when i set it to 100dp it works fine, the items show, but when i set it to wrap or match parent it clips and only show one or non of the items, i can see that there is a scroll bar at the side as well, how can i make it wrap?
<RelativeLayout
android:id="#+id/expandable_rl"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="#dimen/xlarge">
<ListView
android:id="#+id/lisview"
android:layout_width="match_parent"
android:layout_height="100dp"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true"
android:layout_alignParentEnd="true"
app:layout_constraintVertical_bias="1.0"
android:layout_alignParentBottom="true"
app:layout_constraintHorizontal_bias="0.0" />
</RelativeLayout>
and this is how i am setting it, its just to test it, its located in a recycler view
holder.list.adapter = ArrayAdapter(holder.itemView.context, R.layout.simple_item, arrayListOf("hello","hi","testing"))
this is how i expand the expandable layout
holder.itemView.setOnClickListener {
if (unitsList[position].isExpandable) {
holder.expandableRL.visibility = if (holder.expandableRL.visibility == View.GONE) View.VISIBLE else View.GONE
}
}
i tried using notifyItemChanged(position) but it made it expand then immediately collapse for some reason
i am new here and don't know how to fix this at the moment

A fully wrapped list means it doesn't scroll, as all of items are visible.
If that is the case, why using a ListView in the first place.
Here is a suggestion to make use of LinearLayout instead.
XML for RecyclerView item:
<androidx.constraintlayout.widget.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="wrap_content"
>
<Button
android:id="#+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent"
android:text="Click Me" />
<LinearLayout
android:id="#+id/expandable_rl"
android:layout_width="0dp"
android:layout_height="wrap_content"
app:layout_constraintTop_toBottomOf="#id/button"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent"
android:visibility="gone"
android:orientation="vertical">
</LinearLayout>
</androidx.constraintlayout.widget.ConstraintLayout>
And Here's the adapter:
class RecyclerAdapter: RecyclerView.Adapter<RecyclerView.ViewHolder>() {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder {
return ViewHolder(
LayoutInflater.from(parent.context).inflate(
R.layout.recycler_item,
parent,
false
)
)
}
override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) {
(holder as? ViewHolder)?.itemView?.let { itemView ->
val expandable = itemView.findViewById<LinearLayout>(R.id.expandable_rl)
createItems(expandable)
itemView.findViewById<Button>(R.id.button).setOnClickListener {
expandable.visibility = View.VISIBLE
}
}
}
private fun createItems(expandable: LinearLayout) {
listOf("Hi", "Hello", "Goodbye").forEach { word ->
val item = createItem(expandable.context, word)
expandable.addView(item)
}
}
private fun createItem(context: Context, word: String): View {
return LinearLayout(context).apply {
layoutParams = LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT)
orientation = LinearLayout.VERTICAL
gravity = Gravity.CENTER
addView(
TextView(context).apply {
layoutParams = LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT)
text = word
}
)
}
}
override fun getItemCount(): Int {
return 30
}
class ViewHolder(view: View): RecyclerView.ViewHolder(view)
}
This is a basic design, but you can take it from here and design what you need.

4 clickable views in one Iteme of recyclerView (kotlin)

i want set many buttons (i mean clickable views) in item of recyclerView like every item has download,play,stop,delete how can i do that? if i setOnlickListener like holder.download_image.setOnClickListenr(){} its works for all item i want every item has difrent link for download
class RecyclerAdapter(private val soundList: List<SoundItem>,private val mListener: AdapterView.OnItemClickListener?) :
RecyclerView.Adapter<RecyclerAdapter.RecyclerViewHolder>() {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerViewHolder {
val itemView =
LayoutInflater.from(parent.context).inflate(R.layout.recycler_view, parent, false)
return RecyclerViewHolder(itemView)
}
override fun onBindViewHolder(holder: RecyclerViewHolder, position: Int) {
val currnetItem = soundList[position]
holder.soundNmae.text = currnetItem.soundName
holder.play_image.setImageResource(currnetItem.playImage)
holder.stop_image.setImageResource(currnetItem.stopImage)
holder.download_image.setImageResource(currnetItem.donloadImage)
holder.delete_image.setImageResource(currnetItem.deleteImage)
}
override fun getItemCount() = soundList.size
class RecyclerViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
val soundNmae = itemView.soundName
val play_image = itemView.play_image
val stop_image = itemView.stop_image
val download_image = itemView.download_image
val delete_image = itemView.delete_image
}
}
this is acivity for recyclerView im new in kotlin sorry if my question is maybe simple or i couldent say if what is my mean
class RelaxSoundActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_relax_sound)
val exampleList=generatorSoundList(500)
recyceler_view.adapter=RecyclerAdapter(exampleList)
recyceler_view.layoutManager=LinearLayoutManager(this)
recyceler_view.setHasFixedSize(true)
}
fun generatorSoundList(size:Int ):List<SoundItem>{
val list=ArrayList<SoundItem>()
for(i in 0 until size){
val drawable=when(i % 5){
0->R.drawable.ic_play_arrow_black_24dp
1->R.drawable.ic_play_arrow_black_24dp
2->R.drawable.ic_play_arrow_black_24dp
3->R.drawable.ic_play_arrow_black_24dp
else->R.drawable.ic_play_arrow_black_24dp
}
val drawable2=when(i % 5){
0->R.drawable.ic_stop_black_24dp
1->R.drawable.ic_stop_black_24dp
2->R.drawable.ic_stop_black_24dp
3->R.drawable.ic_stop_black_24dp
else->R.drawable.ic_stop_black_24dp
}
val drawable3=when(i % 5){
0->R.drawable.ic_file_download_black_24dp
1->R.drawable.ic_file_download_black_24dp
2->R.drawable.ic_file_download_black_24dp
3->R.drawable.ic_file_download_black_24dp
else->R.drawable.ic_file_download_black_24dp
}
val drawable4=when(i % 5){
0->R.drawable.ic_delete_black_24dp
1->R.drawable.ic_delete_black_24dp
2->R.drawable.ic_delete_black_24dp
3->R.drawable.ic_delete_black_24dp
else->R.drawable.ic_delete_black_24dp
}
val item=SoundItem("item $i" ,drawable,drawable2,drawable3,drawable4)
list+=item
}
return list
}
}
and recycler_view.xml file is here
<?xml version="1.0" encoding="utf-8"?>
<androidx.cardview.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent" android:layout_height="wrap_content"
>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal"
android:padding="8dp"
>
<TextView
android:id="#+id/soundName"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="TextView"
android:textSize="20dp"/>
<ImageView
android:id="#+id/play_image"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
app:srcCompat="#drawable/ic_play_arrow_black_24dp" />
<ImageView
android:id="#+id/stop_image"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
app:srcCompat="#drawable/ic_stop_black_24dp" />
<ImageView
android:id="#+id/download_image"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
app:srcCompat="#drawable/ic_file_download_black_24dp" />
<ImageView
android:id="#+id/delete_image"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
app:srcCompat="#drawable/ic_delete_black_24dp" />
</LinearLayout>
</androidx.cardview.widget.CardView>

you can do it in multiple ways. You can add click listeners on your views and directly perform the operation in your adapter or you can transfer function in your recycler view holder class.
So for short cut I can just give you the way that you can understand the process.
In you adapter onBindViewHolder you can add
holder.download_image.setOnCLickListener{
val downloadLink = currnetItem.getDownloadLink()
// Download task start by this download link
}
So this one click listener on download image will be effected on each item and perform separately.

IMO you have to attach an clicklistener to each button, and then you could either make a callback to the adapter/activity and handle it from there on.
If you yous the View.OnClickListener, then you always have the clicked view. From there on, it is just a matter of writing a switch statement, where you can determine via the id of the clicked view, which action was selected.
If you need extra data, you could just add a tag to the view, and pass it via the clickListener.

Android RecyclerView Adapter DataBinding - cannot find symbol {layout}BindingImpl

I have a Fragment that displays a list of cities with weather informations. I am using a RecyclerView and I am trying to implement the Data Binding Library in my RecyclerView Adapter but for some reason I get this compile error :
> error: cannot find symbol import
com.example.zach.weatherapp.databinding.CityListItemBindingImpl;
> ^
> symbol: class CityListItemBindingImpl
> location: package com.example.zach.weatherapp.databinding
It's an auto generated class so i really don't know where the error is. I had the same error previously for other layouts when there was someting wrong in the xml file but here it seems fine.
ForecastAdapter.kt
package com.example.zach.weatherapp.Adapter
import ...
class ForecastAdapter(var myDataset: List<City>) :
RecyclerView.Adapter<ForecastAdapter.ForecastViewHolder>() {
var context:Context?=null
// Provide a reference to the views for each data item
// Complex data items may need more than one view per item, and
// you provide access to all the views for a data item in a view holder.
class ForecastViewHolder(var binding: CityListItemBinding) : RecyclerView.ViewHolder(binding.root){
fun bind(city: City){
binding.city = city
}
}
// Create new views (invoked by the layout manager)
override fun onCreateViewHolder(parent: ViewGroup,
viewType: Int): ForecastAdapter.ForecastViewHolder {
context = parent.context
val layoutIdForListItem = R.layout.city_list_item
val inflater = LayoutInflater.from(context)
val shouldAttachToParentImmediately = false
val binding = DataBindingUtil.inflate<CityListItemBinding>(inflater,layoutIdForListItem,parent,shouldAttachToParentImmediately)
//val view = inflater.inflate(layoutIdForListItem, parent, shouldAttachToParentImmediately)
return ForecastViewHolder(binding)
}
// Replace the contents of a view (invoked by the layout manager)
override fun onBindViewHolder(holder: ForecastViewHolder, position: Int) {
val city = myDataset[position]
holder.bind(city)
Glide.with(context)
.load("http://openweathermap.org/img/w/${city.weather[0].icon}.png")
.into(holder.binding.forceastImageView)
holder.binding.container.setOnClickListener{ view: View ->
Timber.d("Clicked on city %s",city.name)
Navigation.findNavController(view).navigate(ListFragmentDirections.actionListFragmentToForecastDetailsFragment(city.id))}
}
// Return the size of your dataset (invoked by the layout manager)
override fun getItemCount() = myDataset.size
}
city_list_item.xml
<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
xmlns:android="http://schemas.android.com/apk/res/android">
<data>
<variable name="city" type="com.example.zach.weatherapp.data.City"/>
</data>
<androidx.constraintlayout.widget.ConstraintLayout
android:orientation="horizontal"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="#+id/container">
<TextView
tools:text="Caen"
android:text="#{city.name}"
android:layout_width="wrap_content"
android:layout_height="wrap_content" android:id="#+id/city_name_textview"
app:layout_constraintStart_toStartOf="parent" android:layout_marginStart="16dp"
android:layout_marginTop="16dp" app:layout_constraintTop_toTopOf="parent"
android:fontFamily="#font/roboto_light" android:textSize="22sp" android:textStyle="bold"
android:maxLines="1" android:ellipsize="end"/>
<TextView
tools:text="Sunny"
android:text="#{city.weather[0].description}"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="#+id/city_forecast_textview" app:layout_constraintStart_toStartOf="parent"
android:layout_marginStart="16dp"
app:layout_constraintTop_toBottomOf="#+id/city_name_textview" android:fontFamily="#font/roboto_light"
android:layout_marginBottom="16dp" app:layout_constraintBottom_toBottomOf="parent"/>
<ImageView
android:layout_width="48dp"
android:layout_height="48dp" app:srcCompat="#drawable/sunny"
android:id="#+id/forceast_imageView" android:layout_marginTop="8dp"
app:layout_constraintTop_toTopOf="parent" android:layout_marginBottom="8dp"
app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintVertical_bias="0.562"
android:layout_marginEnd="32dp" app:layout_constraintEnd_toStartOf="#+id/temperatures_layout"/>
<LinearLayout
android:orientation="vertical"
android:layout_width="wrap_content"
android:layout_height="wrap_content" android:id="#+id/temperatures_layout"
app:layout_constraintEnd_toEndOf="parent" android:layout_marginEnd="16dp" android:layout_marginBottom="8dp"
app:layout_constraintBottom_toBottomOf="parent" android:layout_marginTop="8dp"
app:layout_constraintTop_toTopOf="parent">
<TextView
tools:text="15°"
android:text="#{city.main.temp_max}"
android:layout_width="wrap_content"
android:layout_height="wrap_content" android:id="#+id/max_temperature_textview"
android:fontFamily="#font/roboto_light"
tools:layout_editor_absoluteY="17dp" tools:layout_editor_absoluteX="313dp"/>
<TextView
tools:text="9°"
android:text="#{city.main.temp_min}"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="#+id/min_temperature_textview"
android:fontFamily="#font/roboto_light" tools:layout_editor_absoluteY="45dp"
tools:layout_editor_absoluteX="321dp" android:layout_gravity="right"/>
</LinearLayout>
</androidx.constraintlayout.widget.ConstraintLayout>
</layout>
It might just be an Android Studio error because the xml file seems fine.
UPDATE :
Error seems to come from Xml. I removed the android:text="#{city.xxx}" in my xml layout and instead updated my textViews manually in my ViewHolder bind method like so :
fun bind(boundCity: City){
with(binding){
cityNameTextview.text = boundCity.name
cityForecastTextview.text = boundCity.weather[0].description
maxTemperatureTextview.text = "${boundCity.main.temp_max}°"
minTemperatureTextview.text = "${boundCity.main.temp_min}°"
Glide.with(root.context)
.load("http://openweathermap.org/img/w/${boundCity.weather[0].icon}.png")
.into(forceastImageView)
container.setOnClickListener{ view: View ->
Timber.d("Clicked on city %s",boundCity.name)
Navigation.findNavController(view).navigate(ListFragmentDirections.actionListFragmentToForecastDetailsFragment(boundCity.id))}
}
}
And I no longer get the error. The error comes whenever I add android:text="#{city.xx}" in my textviews and bind the city variable in the bind method. I still don't know why though....

This should work for you I believe;
class ForecastAdapter(private var myDataset: List<City>) : RecyclerView.Adapter<ForecastAdapter.ForecastViewHolder>() {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ForecastAdapter.ForecastViewHolder {
val itemBinding = CityListItemBinding.inflate(LayoutInflater.from(parent.context), parent, false)
return ForecastViewHolder(itemBinding)
}
override fun onBindViewHolder(holder: ForecastViewHolder, position: Int) {
val city = myDataset[position]
holder.bind(city)
}
override fun getItemCount() = myDataset.size
inner class ForecastViewHolder(var binding: CityListItemBinding) : RecyclerView.ViewHolder(binding.root){
fun bind(boundCity: City){
with(binding) {
city = boundCity
Glide.with(root.context)
.load("http://openweathermap.org/img/w/${city.weather[0].icon}.png")
.into(forceastImageView)
container.setOnClickListener { view ->
Timber.d("Clicked on city %s", city.name)
Navigation.findNavController(view).navigate(ListFragmentDirections.actionListFragmentToForecastDetailsFragment(city.id))
}
}
}

Hey you could try adding the following line after the <data> tag :
<import type="android.view.View" />
I found that worked for me when I had that error.

How to change attribute of view programatically from the view in my recyclerView in my fragment?

I set the margin of the view (card view) in my xml of my item file, this xml item file will be used in for my recyclerView adapter.
As you can see in my xml below, that I have given margin to top, bottom, start and end. and I want to change the margin from my fragment
Here is my xml file, item_category_list.xml:
<?xml version="1.0" encoding="utf-8"?>
<androidx.cardview.widget.CardView
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"
app:cardCornerRadius="8dp"
app:cardElevation="4dp"
android:id="#+id/cardView_item_category_list" android:layout_marginStart="8dp" android:layout_marginEnd="8dp"
android:layout_marginBottom="8dp" android:layout_marginTop="8dp">
<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"
android:background="#android:color/background_light">
<ImageView
android:layout_width="0dp"
android:layout_height="0dp"
app:srcCompat="#drawable/logo_apps"
android:id="#+id/categoryImageView_Item"
android:layout_marginTop="16dp"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintStart_toStartOf="parent"
android:layout_marginStart="24dp"
app:layout_constraintEnd_toEndOf="parent"
android:layout_marginEnd="24dp"
app:layout_constraintDimensionRatio="w,1:1" android:scaleType="centerCrop"/>
<TextView
android:text="#string/Category"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="#+id/categoryName_textView_item"
app:layout_constraintTop_toBottomOf="#+id/categoryImageView_Item"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
android:layout_marginStart="4dp"
app:layout_constraintEnd_toEndOf="parent"
android:layout_marginEnd="4dp"
android:textAlignment="center"
android:minLines="1"
android:maxLines="2"
app:autoSizeTextType="uniform"
app:autoSizeMinTextSize="10sp"
app:autoSizeMaxTextSize="15sp"
app:autoSizeStepGranularity="1sp"
android:layout_marginBottom="24dp"
android:layout_marginTop="24dp"/>
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.cardview.widget.CardView>
Here is the adapter:
class CategoryAdapter(val context: Context, val categories: List<Category>) : RecyclerView.Adapter<CategoryAdapter.ViewHolderCategory>() {
private lateinit var mListener : CategoryAdapterListener
interface CategoryAdapterListener {
fun onItemClick(position: Int)
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolderCategory {
val layoutInflater = LayoutInflater.from(parent.context)
val itemView = layoutInflater.inflate(R.layout.item_category_list,parent, false)
return ViewHolderCategory(itemView,mListener)
}
override fun getItemCount(): Int {
return categories.size
}
override fun onBindViewHolder(holder: ViewHolderCategory, position: Int) {
val category = categories[position]
holder.categoryNameTextView.text = category.name
Glide
.with(context)
.load(category.getFormattedImageURL())
.into(holder.categoryImageView)
}
inner class ViewHolderCategory(itemView: View, listener: CategoryAdapterListener) : RecyclerView.ViewHolder(itemView) {
val categoryImageView = itemView.findViewById<ImageView>(R.id.categoryImageView_Item)
val categoryNameTextView = itemView.findViewById<TextView>(R.id.categoryName_textView_item)
val cardView = itemView.findViewById<CardView>(R.id.cardView_item_category_list)
init {
itemView.setOnClickListener {
val position = adapterPosition
if (position != RecyclerView.NO_POSITION) {
listener.onItemClick(position)
}
}
}
}
fun setCategoryAdapterListener(listener: CategoryAdapterListener) {
mListener = listener
}
}
and in the fragment, I set the adapter to the recycler view:
val categoryAdapter = CategoryAdapter(mContext,parentCategory)
val layoutManager = GridLayoutManager(mContext,4,RecyclerView.VERTICAL,false)
recyclerViewParentCategory.adapter = categoryAdapter
recyclerViewParentCategory.layoutManager = layoutManager
recyclerViewParentCategory.setHasFixedSize(true)
I want to change that margin in card view in my item_category_list.xml programatically in my java/kotlin file (in my fragment file), so I can change the margin from my fragment.
So how can I achieve it ? Java/Kotlin any language is preferred.

First Of all its a long way . So i'm just suggesting a way .
First of all . In your Fragment when some action happen you need to change cardview
size in adapter list item xml.
So . You need a interface for that (Let's say interface ChangeMargin). create
interface in Fragment and implement that interface in your adapter like this
class CategoryAdapter(val context: Context, val categories: List<Category>):RecyclerView.Adapter<CategoryAdapter.ViewHolderCategory>(),ChangeMargin()
For how to create interface so can go through this
Now in that interface you need to get cardview and assign new margin .
#Override
public void ChangeMargin() {
val linear_params=LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT,LinearLayout.LayoutParams.WRAP_CONTENT)
linear_params.setMargins(leftMargin,topmargin,rightMargin,bottomMargin)
cardView?.layoutParams=linear_params
}
and don't forget to notify adapter

You can do something like this.
Make id of cardview , create instance of it in your adapter and do this code
ViewGroup.MarginLayoutParams layoutParams =
(ViewGroup.MarginLayoutParams) myCardView.getLayoutParams();
layoutParams.setMargins(10, 10, 10, 10);
myCardView.requestLayout();

To set margins to the cardView, you will have to create layoutParams, set margins to it and then set it as cardView LayoutParams like:
inner class ViewHolderCategory(itemView: View, listener: CategoryAdapterListener) : RecyclerView.ViewHolder(itemView) {
val categoryImageView = itemView.findViewById<ImageView>(R.id.categoryImageView_Item)
val categoryNameTextView = itemView.findViewById<TextView>(R.id.categoryName_textView_item)
val cardView = itemView.findViewById<CardView>(R.id.cardView_item_category_list)
//Main code here
val lparams=LinearLayout.LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT,LinearLayout.LayoutParams.WRAP_CONTENT)
lparams.setMargins(leftMargin,topmargin,rightMargin,bottomMargin)
cardView?.layoutParams=lparams
}