not able to add a imageview to custom adapter to be shown into a gridview , it is giving classcast exception on setimageresource - casting

Question

package com.ettv.tv.forealz;
import android.content.Context;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;
import androidx.leanback.widget.ArrayObjectAdapter;
import androidx.leanback.widget.HeaderItem;
import androidx.leanback.widget.ListRow;
import com.ettv.tv.R;
`import com.ettv.tv.forealz.model.ModelStore;
`import com.ettv.tv.forealz.model.Topic;
import com.squareup.picasso.Picasso;
import java.util.ArrayList;
import java.util.List;
`import static com.ettv.tv.MovieList.list;
// it is the custom adapter
`public class CustomAdapter2 extends BaseAdapter {
`
#Override
public int getCount() {
return topics3.size();
}
#Override
public Object getItem(int position) {
return position;
}
#Override
public long getItemId(int position) {
` return position;
}
#Override
public View getView(int position, View convertView,
ViewGroup parent) {
if (convertView == null) {
convertView = thisInflater.inflate( R.layout.row_item, parent,
false );
//TextView textHeading = (TextView)
convertView.findViewById(R.id.petnames);
ImageView thumbnailImage = (ImageView)
convertView.findViewById(R.id.image);
final List list = new ArrayList<Integer>();
for (Topic topic : topics3) {
thumbnailImage.setImageResource(topics3.get(position).getmDrawable());
}
}
}
return convertView;
}
private List topics3;
private LayoutInflater thisInflater;
public CustomAdapter2(Context con, List<Topic> topics2) {
` this.thisInflater = LayoutInflater.from(con);
this.topics3=topics2;
Log.d("check7",this.topics3.toString());
Log.d("check8", String.valueOf(topics2.size()));
}
}
}