Holder cannot resolve symbol in adapter

Question

I have been following this tutorial and the issue I'm hitting is that it can't resolve the symbol for nameText and countText. I have followed the tutorial as closely as possible and tried rebuilding the code but it hits the error and gives me a compilation failed message. I'm not quite sure what to do to fix it. Here is the code so far:

package com.example.android.sqliteappexamplegrocerylist;

import android.content.Context;
import android.database.Cursor;
import android.support.annotation.NonNull;
import android.support.v7.widget.RecyclerView;
import android.text.Layout;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import org.w3c.dom.Text;

public class GroceryAdapter extends RecyclerView.Adapter {

    private Context mContext;
    private Cursor mCursor;

    public GroceryAdapter(Context context, Cursor cursor) {
        mContext = context;
        mCursor = cursor;
    }

    public class GroceryViewHolder extends RecyclerView.ViewHolder {
        public TextView nameText;
        public TextView countText;

        public GroceryViewHolder(View itemView) {
            super(itemView);

            nameText = itemView.findViewById(R.id.textview_name_item);
            countText = itemView.findViewById(R.id.textview_amount_item);
        }
    }

    @NonNull
    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        LayoutInflater inflater = LayoutInflater.from(mContext);
        View view = inflater.inflate(R.layout.grocery_item, parent, false);
        return new GroceryViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull RecyclerView.ViewHolder holder, int position) {
        if(!mCursor.move(position)) {
            return;
        }

        String name = mCursor.getString(mCursor.getColumnIndex(GroceryContract.GroceryEntry.COLUMN_NAME));
        int amount = mCursor.getInt(mCursor.getColumnIndex(GroceryContract.GroceryEntry.COLUMN_AMOUNT));

        holder.nameText.setText(name);
        holder.countText.setText(String.valueOf(amount));
    }

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

    public void swapCursor(Cursor newCursor) {
        if (mCursor != null) {
            mCursor.close();
        }

        mCursor = newCursor;

        if(newCursor != null) {
            notifyDataSetChanged();
        }
    }
}

Answer 1

在类声明中应该是

public class GroceryAdapter extends RecyclerView.Adapter<GroceryAdapter.GroceryViewHolder>