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Grouping by standardized categories

Now that you have standardized the categories of your electronics inventory, you would like to compute the quantity of each category. Merge the quantities into category sums.

This exercise is part of the course

Cleaning Data in Java

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Exercise instructions

  • Define an enum map to store the quantity of each ProductCategory in stockByCategory.
  • Merge the quantities into category sums in stockByCategory.

Hands-on interactive exercise

Have a go at this exercise by completing this sample code.

import java.util.Collections;
import java.util.EnumMap;
import java.util.HashMap;
import java.util.Map;

public class ElectronicsCategoryExample {
    public enum ProductCategory {
        ELECTRONICS,
        HOME_APPLIANCES,
        UNCATEGORIZED;
    }

    public static void main(String[] args) {
    	Map categoryMap = new HashMap<>();
        categoryMap.put("Home Appliances", ProductCategory.HOME_APPLIANCES);
        categoryMap.put("home appliances", ProductCategory.HOME_APPLIANCES);
        categoryMap.put("HomeAppliances", ProductCategory.HOME_APPLIANCES);
        categoryMap.put("Electronics", ProductCategory.ELECTRONICS);
        categoryMap.put("electronics", ProductCategory.ELECTRONICS);
        categoryMap.put("Electronic", ProductCategory.ELECTRONICS);
        
        Map rawData = Map.of(
                "Home Appliances", 10,
                "home appliances", 20,
                "HomeAppliances", 30,
                "Electronics", 10,
                "electronics", 20,
                "Electronic", 10);

        // Define an enum map to store the quantity of each ProductCategory
        Map stockByCategory = new ____<>(____.class);

        // Merge the quantities into category sums
        rawData.forEach((raw, quantity) -> ____.____(categoryMap.get(raw), quantity, Integer::sum));

		System.out.println("Stock by category:");
        System.out.println(stockByCategory);
    }
}
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