RecyclerView with Adapter and OnClickListener implemented

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>

<FrameLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/rv_numbers"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>
</FrameLayout>

ListItemClickListener.java

public interface ListItemClickListener {
  void onListItemClick(int clickedItemIndex);
}

MainActivity.java

// Implement Adapter.ListItemClickListener
public class MainActivity extends AppCompatActivity implements MyRecyclerViewAdapter.ListItemClickListener {
  
  private static final int NUM_LIST_ITEMS = 100;
  
  public MyRecyclerViewAdapter mAdapter;
  public RecyclerView mList;
  
  // Toast is used to create a reaction to the item-click
  private Toast mToast;
  
  @Override
    protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      
      mList = (RecyclerView) findViewById(R.id.rv_numbers);
     
      LinearLayoutManager layoutManager = new LinearLayoutManager(this);
      mList.setLayoutManager(layoutManager);
      mList.setHasFixedSize(true);
      mAdapter = new MyRecyclerViewAdapter(NUM_LIST_ITEMS, this);
      mList.setAdapter(mAdapter);
    }
  
    public void onListItemClick(int clickedItemIndex) {
        if (mToast != null) {
            mToast.cancel();
        }
        mToast = Toast.makeText(this, "Item #" + clickedItemIndex, Toast.LENGTH_LONG);
        mToast.show();
    }
      
}

MyRecyclerViewAdapter.java

public class MyRecyclerViewAdapter extends RecyclerView.Apadter<MyRecyclerViewAdapter.NumberViewHolder> {
     
    final private ListItemClickListener mOnClickListener;
    private static int viewHolderCount;

    private int mNumberItems;
  
    public MyRecyclerViewAdapter(int numberOfItems, ListItemClickListener listener) {
        mNumberItems = numberOfItems;
        mOnClickListener = listener;
        viewHolderCount = 0;
    }
 
    @Override
    public NumberViewHolder onCreateViewHolder(ViewGroup viewGroup, int viewType) {
        Context context = viewGroup.getContext();
        LayoutInflater inflater = LayoutInflater.from(context);

        View view = inflater.inflate(R.layout.number_list_item, viewGroup, false);
        NumberViewHolder viewHolder = new NumberViewHolder(view);
      
        return viewHolder;
    }

    @Override
    public void onBindViewHolder(NumberViewHolder holder, int position) {
        holder.bind(position);
    }

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

    class NumberViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {

        TextView listItemNumberView;
        
        public NumberViewHolder(View itemView) {
            super(itemView);

            listItemNumberView = (TextView) itemView.findViewById(R.id.tv_item_number);
            itemView.setOnClickListener(this);
        }
      
        void bind(int listIndex) {
            listItemNumberView.setText(String.valueOf(listIndex));
        }

        // Override onClick, passing the clicked item's position (getAdapterPosition()) to mOnClickListener via its onListItemClick method
        @Override
        public void onClick(View v) {
            int clickedPosition = getAdapterPosition();
            mOnClickListener.onListItemClick(clickedPosition);
        }

    }
  
  
}

number_list_item.xml

<?xml version="1.0" encoding="utf-8"?>

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:padding="16dp">

    <TextView
        android:id="@+id/tv_item_number"
        style="@style/TextAppearance.AppCompat.Title"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_vertical|start"
        android:fontFamily="monospace"
        android:textSize="42sp" />
     
</FrameLayout>