CODEWITHSUNDEEP
javaarraysjava-8
Lily
Lily

Reputation: 707

adding the items integer values in java

I have data on following pattern and I just want to add the number of similar items and stored in a List. Whereas , the items like quantity= 1, ingredient=chicken, unit =kg , The unit will be always kg. I have List<itemsDTO> I want to add similar items from this list. [{1,"kg","chicken"} , {2.2,"kg","beaf"} , {0.25,"kg","chicken"}]

public class itemsDTO {

    double quantity;
    String unit;
    String ingredient;

}

I have tried this code

        List<itemsDTO> itemsDTOList = new ArrayList<>();
            for (int i = 0; i < itemsDTOList.size(); i++) {
            for (int j = 0; j < itemsDTOList.size(); j++) {

                if (itemsDTOList.get(i).getIngredient().equalsIgnoreCase(itemsDTOList.get(j).getIngredient())) {
                    int sum;
                    sum = itemsDTOList.get(i).getQuantity() + itemsDTOList.get(j).getQuantity();
                }
            }

        }

Expected Output 1.25 kg chicken,2.2 kg beaf

Upvotes: 0

Views: 63

Answers (1)

Hadi
Hadi

Reputation: 17289

You can use toMap collector with merge function: 

BinaryOperator<itemsDTO> sumQuantity = (a, b) -> {
        a.setQuantity(a.getQuantity() + b.getQuantity());
        return a;
    };
itemsDTOList.stream()
    .collect(Collectors.toMap(itemsDTO::getIngredient, Function.identity(), sumQuantity))
    .values();

Upvotes: 3

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