public class ItemBaseAdapter extends BaseAdapter {

        Context context;
        List<Item> list;

        ItemBaseAdapter(Context c, List<Item> l){
            context = c;
            list = l;
        }

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

        @Override
        public Object getItem(int position) {
            return list.get(position);
        }

        @Override
        public long getItemId(int position) {
            return position;
        }

        public List<Item> getList(){
            return list;
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            // TODO Auto-generated method stub
            return null;
        }
    }

    public class ItemGridAdapter extends ItemBaseAdapter {

        ItemGridAdapter(Context c, List<Item> l) {
            super(c, l);
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            View gridrowView = convertView;

            // reuse views
            if (gridrowView == null) {
                LayoutInflater inflater = ((Activity) context).getLayoutInflater();
                gridrowView = inflater.inflate(R.layout.criardeck, null);

                GridViewHolder gridviewHolder = new GridViewHolder();
                gridviewHolder.carta = gridrowView.findViewById(R.id.imageViewCarta);
                gridrowView.setTag(gridviewHolder);
            }

            GridViewHolder holder = (GridViewHolder) gridrowView.getTag();
            holder.carta.setImageDrawable(list.get(position).ItemDrawable);

            gridrowView.setOnDragListener(new ItemOnDragListener(list.get(position)));

            return gridrowView;
        }
    }

    //items stored in ListView
    public static class Item {
        Drawable ItemDrawable;

        Item(Drawable drawable) {
            ItemDrawable = drawable;
        }
    }

static class GridViewHolder {
        ImageView carta;
    }