Как встроить нативную рекламу Admob и промежуточную рекламу в Recyclerview + Cardview с помощью GridLayout

Question

Я обращаюсь за помощью, поскольку я устал от просмотра видео в видео и от группы к группе за помощью.Всякий раз, когда я встраиваю коды, приложение постоянно падает.

В Recyclerview + Cardview с GridLayout. Я пытаюсь встраивать нативную рекламу Admob на домашнюю страницу и промежуточную рекламу, когда кто-то нажимает на обложку книги, и когда реклама закрыта, он может видеть подробное описание.В подробном описании хочется встраивать нативную рекламу два-три раза.

package com.demotxt.myapp.recyclerview;

import android.content.Context;
import android.content.Intent;
import android.support.v7.widget.CardView;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;

import com.google.android.gms.ads.InterstitialAd;

import java.util.List;


public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.MyViewHolder> {

    private Context mContext ;
    private List<Book> mData ;


    public RecyclerViewAdapter(Context mContext, List<Book> mData) {
        this.mContext = mContext;
        this.mData = mData;

    }

    @Override
    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

        View view ;
        LayoutInflater mInflater = LayoutInflater.from(mContext);
        view = mInflater.inflate(R.layout.cardveiw_item_book,parent,false);
        return new MyViewHolder(view);
    }

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

        holder.tv_book_title.setText(mData.get(position).getTitle());
        holder.img_book_thumbnail.setImageResource(mData.get(position).getThumbnail());
        holder.cardView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                Intent intent = new Intent(mContext,Book_Activity.class);

                // passing data to the book activity
                intent.putExtra("Title",mData.get(position).getTitle());
                intent.putExtra("Description",mData.get(position).getDescription());
                intent.putExtra("Thumbnail",mData.get(position).getThumbnail());

                // start the activity
                mContext.startActivity(intent);



            }
        });



    }

    @Override
    public int getItemCount() {
        return mData.size();
    }

    public static class MyViewHolder extends RecyclerView.ViewHolder {

        TextView tv_book_title;
        ImageView img_book_thumbnail;
        CardView cardView ;

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

            tv_book_title = (TextView) itemView.findViewById(R.id.book_title_id) ;
            img_book_thumbnail = (ImageView) itemView.findViewById(R.id.book_img_id);
            cardView = (CardView) itemView.findViewById(R.id.cardview_id);


        }
    }


};

package com.demotxt.myapp.recyclerview;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.GridLayoutManager;
import android.support.v7.widget.RecyclerView;

import com.google.android.gms.ads.AdListener;
import com.google.android.gms.ads.AdRequest;
import com.google.android.gms.ads.InterstitialAd;
import com.google.android.gms.ads.MobileAds;

import java.util.ArrayList;
import java.util.List;


public class MainActivity extends AppCompatActivity {

    List<Book> lstBook ;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        MobileAds.initialize(this,
                getString(R.string.admob_app_id));

        lstBook = new ArrayList<>();


        lstBook.add(new Book("The Vegitarian","Categorie Book",getString(R.string.description_thevigitarian),R.drawable.thevigitarian));
        lstBook.add(new Book("Capitalism","Economics", getString(R.string.description_capitalism),R.drawable.capitalism));
        lstBook.add(new Book("Fooled by Randomness","Economics",getString(R.string.description_fooledby),R.drawable.fooledby));
        lstBook.add(new Book("Antifragile","Economics",getString(R.string.description_antifragile),R.drawable.antifragile));
        lstBook.add(new Book("Freakonomics","Economics",getString(R.string.description_freaknomics),R.drawable.freaknomics));
        lstBook.add(new Book("The Wild Robot","Categorie Book",getString(R.string.description_thewildrobot),R.drawable.thewildrobot));
        lstBook.add(new Book("Maria Semples","Categorie Book",getString(R.string.description_mariasemples),R.drawable.mariasemples));
        lstBook.add(new Book("The Martian","Categorie Book",getString(R.string.description_themartian),R.drawable.themartian));
        lstBook.add(new Book("He Died with...","Categorie Book",getString(R.string.description_hediedwith),R.drawable.hediedwith));
        lstBook.add(new Book("The Vegitarian","Categorie Book",getString(R.string.description_thevigitarian),R.drawable.thevigitarian));
        lstBook.add(new Book("The Wild Robot","Categorie Book",getString(R.string.description_thewildrobot),R.drawable.thewildrobot));
        lstBook.add(new Book("Maria Semples","Categorie Book",getString(R.string.description_thevigitarian),R.drawable.mariasemples));
        lstBook.add(new Book("The Martian","Categorie Book",getString(R.string.description_themartian),R.drawable.themartian));
        lstBook.add(new Book("He Died with...","Categorie Book",getString(R.string.description_hediedwith),R.drawable.hediedwith));
        lstBook.add(new Book("The Vegitarian","Categorie Book",getString(R.string.description_thevigitarian),R.drawable.thevigitarian));
        lstBook.add(new Book("The Wild Robot","Categorie Book",getString(R.string.description_thewildrobot),R.drawable.thewildrobot));
        lstBook.add(new Book("Maria Semples","Categorie Book",getString(R.string.description_mariasemples),R.drawable.mariasemples));
        lstBook.add(new Book("The Martian","Categorie Book",getString(R.string.description_themartian),R.drawable.themartian));
        lstBook.add(new Book("He Died with...","Categorie Book",getString(R.string.description_hediedwith),R.drawable.hediedwith));

        RecyclerView myrv = (RecyclerView) findViewById(R.id.recyclerview_id);
        RecyclerViewAdapter myAdapter = new RecyclerViewAdapter(this,lstBook);
        myrv.setLayoutManager(new GridLayoutManager(this,2));
        myrv.setAdapter(myAdapter);


    }
}