//helper class methods:
   public ArrayList<Entry> date_products_values(String variant) {
        Cursor c = null;
         //initialize arrays
        ArrayList<Entry> values = new ArrayList<>();
        product_labels.clear();
        SQLiteDatabase db = this.getReadableDatabase();
        //open query cursor
         c = db.rawQuery("select p_name ,sum('" + variant + "') as sum \n" +
                "from total_sales\n" +
                "group by product_id ORDER BY sum('" + variant + "') DESC", null);
        int i = 0;
        if (c != null) {

            try {
                while (c.moveToNext()) {
                    //get total sum of variant
                    Double sum = c.getDouble(1);
                    //get top 10
                    if (product_labels.size() < 10) {
                        product_labels.add(mFormat.format(sum).replace(".0", "") + " " +       c.getString(c.getColumnIndex("p_name")));
                        values.add(new Entry(Float.valueOf(String.valueOf(sum)), i));
                    } else {
                       //tried this to get other products as well
                        if (!product_labels.contains("Others")) {
                            product_labels.add(mFormat.format(sum).replace(".0", "") + " Others");
                            values.add(new Entry(Float.valueOf(String.valueOf(sum)), i));
                        }
                    }
                    Log.d("sum_product_values_", String.valueOf(sum) + "/" + c.getString(c.getColumnIndex("p_name")));
                    i++;
                }
            } finally {
                c.close();
            }
        }
        return values;
    }

public ArrayList<String> product_labels() {
        return product_labels;
    }