Single selection in RecyclerView

Question

I know there are no default selection methods in recyclerview class, But I have tried in following way,

public void onBindViewHolder(ViewHolder holder, final         


        

Answer 1

This is how its looks

Inside your Adapter

private int selectedPosition = -1;

And onBindViewHolder

@Override
public void onBindViewHolder(@NonNull MyViewHolder holder, int position) {

    if (selectedPosition == position) {
        holder.itemView.setSelected(true); //using selector drawable
        holder.tvText.setTextColor(ContextCompat.getColor(holder.tvText.getContext(),R.color.white));
    } else {
        holder.itemView.setSelected(false);
        holder.tvText.setTextColor(ContextCompat.getColor(holder.tvText.getContext(),R.color.black));
    }

    holder.itemView.setOnClickListener(v -> {
        if (selectedPosition >= 0)
            notifyItemChanged(selectedPosition);
        selectedPosition = holder.getAdapterPosition();
        notifyItemChanged(selectedPosition);
    });
}

Thats it! As you can see i am just Notifying(updating) previous selected item and newly selected item

My Drawable set it as a background for recyclerview child views

<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:state_focused="false" android:state_selected="true">
    <shape android:shape="rectangle">
        <solid android:color="@color/blue" />
    </shape>
</item>

Answer 2

This is how the Adapter class looks like :

public class MyRecyclerViewAdapter extends RecyclerView.Adapter<MyRecyclerViewHolder>{

Context context;
ArrayList<RouteDetailsFromFirestore> routeDetailsFromFirestoreArrayList_;
public int  lastSelectedPosition=-1;


public MyRecyclerViewAdapter(Context context, ArrayList<RouteDetailsFromFirestore> routeDetailsFromFirestoreArrayList)
{
    this.context = context;
    this.routeDetailsFromFirestoreArrayList_ = routeDetailsFromFirestoreArrayList;
}

@NonNull
@Override
public MyRecyclerViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i)
{
    // LayoutInflater layoutInflater = LayoutInflater.from(mainActivity_.getBaseContext());
    LayoutInflater layoutInflater = LayoutInflater.from(viewGroup.getContext());
    View view = layoutInflater.inflate(R.layout.route_details, viewGroup, false);
    return new MyRecyclerViewHolder(view);
}

@Override
public void onBindViewHolder(@NonNull final MyRecyclerViewHolder myRecyclerViewHolder, final int i) {

    /* This is the part where the appropriate checking and unchecking of radio button happens appropriately */
    myRecyclerViewHolder.mRadioButton.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
        @Override
        public void onCheckedChanged(CompoundButton compoundButton, boolean b) {
            if(b) {
                if (lastSelectedPosition != -1) {
     /* Getting the reference to the previously checked radio button and then unchecking it.lastSelectedPosition has the index of the previously selected radioButton */  
                    //RadioButton rb = (RadioButton) ((MainActivity) context).linearLayoutManager.getChildAt(lastSelectedPosition).findViewById(R.id.rbRadioButton);
                    RadioButton rb = (RadioButton) ((MainActivity) myRecyclerViewHolder.mRadioButton.getContext()).linearLayoutManager.getChildAt(lastSelectedPosition).findViewById(R.id.rbRadioButton);
                    rb.setChecked(false);
                }
                    lastSelectedPosition = i;
                    /* Checking the currently selected radio button */
                    myRecyclerViewHolder.mRadioButton.setChecked(true);
                }
        }
    });
}

@Override
public int getItemCount() {
    return routeDetailsFromFirestoreArrayList_.size();
}
} // End of Adapter Class

Inside MainActivity.java we call the ctor of Adapter class like this. The context passed is of MainActivity to the Adapter ctor :

myRecyclerViewAdapter = new MyRecyclerViewAdapter(MainActivity.this, routeDetailsList);

Answer 3

You need to clear the OnCheckedChangeListener before setting setChecked():

@Override
public void onBindViewHolder(final ViewHolder holder, int position) {

    holder.mRadioButton.setOnCheckedChangeListener(null);
    holder.mRadioButton.setChecked(position == mCheckedPosition);
    holder.mRadioButton.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
        @Override
        public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {

            mCheckedPosition = position;
            notifyDataSetChanged();
        }
    });
}

This way it won't trigger the java.lang.IllegalStateException: Cannot call this method while RecyclerView is computing a layout or scrolling error.