RecyclerView with Adapter does not keep values stored in Android - android-layout

Question

I have the following simple recyclerview layout:
<RelativeLayout
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=".SurvivorPicksheetActivity">
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/recyclerView"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</RelativeLayout>
This recycler view links to the detailed layout of the list items as such:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<FrameLayout 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/rootView"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<androidx.cardview.widget.CardView
android:layout_width="match_parent"
android:layout_height="wrap_content" >
<ImageView
android:id="#+id/background"
android:layout_width="match_parent"
android:layout_height="180dp"
android:layout_centerHorizontal="true"
app:srcCompat="#drawable/gamefield_background" />
<ImageView
android:id="#+id/away"
android:layout_width="160dp"
android:layout_height="150dp"
android:layout_gravity="top|left"/>
<ImageView
android:id="#+id/home"
android:layout_width="160dp"
android:layout_height="150dp"
android:layout_gravity="top|right"
android:scaleX="-1"/>
</androidx.cardview.widget.CardView>
</FrameLayout>
</LinearLayout>
Inside my Adapter java class I have an setOnClickListener for the two ImageView items.
If a user clicks on them the item is selected while the old item is unselected.
The problem I am encountering if that lets say the list of items has 25 items. If I click on the lets say 3rd item, everything works as expected.
Then I scroll to the end of the list, and scroll back up to the top, the selection is not longer valid even thought I clicked/selected prior to scrolling to the end of the list.
I can reclick and item at the top, scroll down and scroll back up and my selection is gone!?
Does anyone know why this is happening and more importantly how i can resolve it!?
UPDATE:
The following is my Adapter class:
public class GameAdapter extends
RecyclerView.Adapter<GameAdapter.GameViewHolder> {
// variable that holds the selected team
private String selectedTeam = "";
#Override
public void onBindViewHolder(GameViewHolder holder, int position) {
final Games game = gameList.get(position);
holder.awayTeamImageView.setOnClickListener(new Button.OnClickListener() {
#Override
public void onClick(View v) {
if (selectedTeam.equals(String.valueOf(game.getHomeId()))) {
// RESET PLAYER SELECTION
selectedTeam = "";
selectedGame = "";
} else {
// SET PLAYER SELECTION
selectedTeam = String.valueOf(game.getHomeId());
selectedGame = String.valueOf(game.getKey());
}
}
}
}
class GameViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
public GameViewHolder(#NonNull View itemView) {
super(itemView);
itemView.setOnClickListener(this);
awayImageView = itemView.findViewById(R.id.away);
homeImageView = itemView.findViewById(R.id.home);
homeImageView.setOnClickListener(this);
awayImageView.setOnClickListener(this);
}
}
Based on my code above, I 'think' I am setting and unsetting the selected team so that when I scroll to the end and back to the top the selected team should remain vs being recycled and not displaying anymore?!

Answer 1

That's because the old Views are being recycled, back to the initial state. And this is a natutral behavior of RecyclerView.
In order to make each item View "memorize" its check/select state, you need to create a field in your model class to record the state, like isChecked or isSelected.

Answer 2

You can use own domain ViewHolder and ViewModel for recycleview.
Android developer documents gives basic understanding of how to create dynamic RecycleView in below link.
https://developer.android.com/guide/topics/ui/layout/recyclerview

Answer 3

This is expected as the views are recycled and lose their values accordingly whenever you scroll up/down the list; further for configuration changes (like screen rotation) the selected views will be lost.
To fix this, you should go for ViewModel to have persistent data even for configuration changes.
But, as a rescuer, assuming the adapter provided list of games gameList is in a persistent storage like mentioned above; then you can:
Create a selection boolean in the Games model class with getter/setter which has a false initially.
When a row is selected from the RecyclerView, then set the boolean to true like gameList.get(selectedPosition).setIsSelected(true)
Then notifyItemChanged() of that position.