String hour = getTimeFormattedInAMPM(sale_obj.getString("created_at"));
                        // 1
                        int index = Collections.singletonList(sales_labels_1).indexOf(hour);
                        int count = 1;
                        if(index < 0){ // hour doesnt exist in sales_label_1
                            sales_labels_1.add(hour);
                            index = 0; // overwrite index
                            Log.d("index_if", String.valueOf(index));
                        }
                        else {
                            Log.d("index_else", String.valueOf(index));
                            int current_count = groupedSales.getInt(hour); // read the current count
                            count = Integer.valueOf(current_count) + 1; // increment by 1
                        }
                        Log.d("index_final", String.valueOf(index));
                        groupedSales.put(hour, count);
                        sales_values_1.add(new Entry(Float.valueOf(String.valueOf(count)), index));