Common adapter for spinner and recyclerView

Question

Can write common adapter for different views? I am interested in common adapter for recyclerView and spinner. In my project i have RecyclerView and Spinner and i want to write base generic adapter for both (RecyclerView and Spinner) Can you help me?

Complex

Answer 1

Yes, You can implement a common adapter for ListView/Spinner and RecyclerView

public static class CommonAdapter extends RecyclerView.Adapter<CommonAdapter.RecycleViewHolder>
            implements ListAdapter {


        private Context mContext;
        private List<String> data;

        public CommonAdapter(Context context, List<String> data) {
            mContext = context;
            this.data = data;
        }

        // Start of recycleview adapter
        @Override
        public RecycleViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
            return new RecycleViewHolder(new TextView(mContext));
        }

        @Override
        public void onBindViewHolder(RecycleViewHolder holder, int position) {
            holder.textView.setText(data.get(position));
        }

        @Override
        public int getItemCount() {
            return getCount();
        }

        public static class RecycleViewHolder extends RecyclerView.ViewHolder {

            public TextView textView;

            public RecycleViewHolder(View itemView) {
                super(itemView);
                textView = (TextView) itemView;
            }
        }

        // Implementation of list adapter(Spinner/ListView)
        @Override
        public boolean areAllItemsEnabled() {
            return true;
        }

        @Override
        public boolean isEnabled(int position) {
            return true;
        }

        @Override
        public void registerDataSetObserver(DataSetObserver observer) {

        }

        @Override
        public void unregisterDataSetObserver(DataSetObserver observer) {

        }

        @Override
        public int getCount() {
            return data.size();
        }

        @Override
        public String getItem(int position) {
            return data.get(position);
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            SpinnerViewHolder holder;
            if (convertView == null) {
                convertView = new TextView(mContext);
                holder = new SpinnerViewHolder();
                holder.textView = (TextView) convertView;
                convertView.setTag(holder);
            } else {
                holder = (SpinnerViewHolder) convertView.getTag();
            }
            holder.textView.setText(getItem(position));
            return convertView;
        }

        @Override
        public int getViewTypeCount() {
            return 0;
        }

        @Override
        public boolean isEmpty() {
            return false;
        }

        public static class SpinnerViewHolder {
            public TextView textView;
        }

    }

This is the basic idea for doing that, You can genirify even more to use the same adapter for all the different ListView/RecyclerView with different datatypes too. But as of now I am giving the basic idea of combined adapters.

The Adapter is extending the RecyclerView.ViewHolder which is required by RecyclerView and I am implementing the same class to ListAdapter which is required by ListView/Spinner.

Symptomatology

Its great! Thank you – Complex

Answer 2

Here is my sample with cursor example for androidx. The idea is to have a common text view id for both. You can check it in xml file provided by android.R.layout.simple_spinner_item and android.R.layout.simple_list_item_1.

import android.database.Cursor;
import android.view.LayoutInflater;
import android.view.ViewGroup;
import android.widget.TextView;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;

/**
 * Common adapter for cursor.
 */
public class CommonAdapter extends RecyclerView.Adapter<CommonAdapter.ViewHolder> {

        private Cursor mCursor;
        private boolean isSpinner;

        public CommonAdapter(boolean isSpinner){
            this.isSpinner = isSpinner;
        }

        @Override
        @NonNull
        public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
            return new ViewHolder(parent, isSpinner);
        }

        @Override
        public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
            if (mCursor.moveToPosition(position)) {
                holder.mText.setText(mCursor.getString(
                        mCursor.getColumnIndexOrThrow(Data.COLUMN_ID)));
            }
        }

        @Override
        public int getItemCount() {
            return mCursor == null ? 0 : mCursor.getCount();
        }

        void setCursor(Cursor cursor) {
            mCursor = cursor;
            notifyDataSetChanged();
        }

        static class ViewHolder extends RecyclerView.ViewHolder {

            final TextView mText;

            ViewHolder(ViewGroup parent, boolean isSpinner) {
                super(LayoutInflater.from(parent.getContext()).inflate(
                        isSpinner?android.R.layout.simple_spinner_item:android.R.layout.simple_list_item_1
                        , parent, false));
                mText = itemView.findViewById(android.R.id.text1);
            }

        }

}

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