String productName = sale_obj.getString("name");
                    double total = sale_obj.getDouble("price");
                    int index = product_labels_1.indexOf(productName);
                    if (index < 0) {
                        // product doesnt exist in product_labels_1
                        product_labels_1.add(productName);
                        product_values_1.add(new Entry((float) total, product_labels_1.size() - 1));
                    } else {
                        // read the current total
                        int current_total = (int) groupedProducts.getDouble(productName);
                        // increment by the total
                        total = current_total + total;
                        product_values_1.set(index, new Entry((float) total, index));
                    }
                    groupedProducts.put(productName, total);