Interview 00

2023_11_23_interview_00.java

import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;
import java.util.stream.IntStream;

interface ItemsRepository {

    List<Integer> findByType(String type);

    // Dummy implementation, but please assume this is a proper DB repository:
    ItemsRepository INSTANCE = type -> IntStream.rangeClosed(1, (int) (Math.random() * 999 + 2))
            .boxed()
            .collect(Collectors.toList());
}

interface PricesRepository {

    Integer findPriceById(Integer id);

    Map<Integer, Integer> findPricesByIds(List<Integer> ids);

    // Dummy implementation, but please assume this is a proper DB repository:
    PricesRepository INSTANCE = id -> 3 * id;
}

class Main {

    public static void main(String[] args) {

        final int allBraceletsPrice = totalPriceOfAllItemsForType("bracelet");
        System.out.println("bracelets: " + allBraceletsPrice);

        final int allNecklacesPrice = totalPriceOfAllItemsForType("necklace");
        System.out.println("necklaces: " + allNecklacesPrice);
    }

    // Focus on the performance of the following method:
    static int totalPriceOfAllItemsForType(final String type) {
        return ItemsRepository.INSTANCE.findByType(type)
                .stream()
                .map(PricesRepository.INSTANCE::findPriceById)
                .mapToInt(Integer::intValue)
                .sum();
    }
}