Method Abstraction Level

methodAbstraction.java

public List<SomeDataFull> methodWithNoAbstraction() {
        // get data from DB for instance
        final List<SomeData> listOfDataFromDb = getDataFromDb(); // a.1

        final List<String> someDataRetrievedIds = listOfDataFromDb.stream().map(SomeData::getId).collect(Collectors.toList()); //a.2
        final Map<String, Boolean> someDataIdMapping = getVerificationFromExternalSystem(someDataRetrievedIds)
                .stream().collect(Collectors.toMap(SomeDataVerification::getId, SomeDataVerification::isOk));

        final List<SomeData> verifiedSomeData = listOfDataFromDb.stream().filter(eachData -> someDataIdMapping.getOrDefault(eachData.getId(), false)) //a.3
                .collect(Collectors.toList());
        final List<String> someDataVerifiedIds = verifiedSomeData.stream().map(SomeData::getId).collect(Collectors.toList());
        final Map<String, SomeData2> idAdditionalDataMapping = getAdditionalData(someDataVerifiedIds).stream()
                .collect(Collectors.toMap(SomeData2::getId, Function.identity()));

        final List<SomeDataFull> mergedFullData = verifiedSomeData.stream().map(eachData -> { // a.4
            final var someData2 = idAdditionalDataMapping.get(eachData.getId());
            return SomeDataFull.builder()
                    .id(eachData.getId())
                    .email(someData2.getEmail())
                    .extraData(someData2.getExtraData())
                    .fileNumber(someData2.getFileNumber())
                    .whateverStuff(eachData.getWhateverStuff())
                    .build();
        }).collect(Collectors.toList());

        return mergedFullData;

    }

    public List<SomeDataFull> methodWithMixAbstraction() {
        final List<SomeData> listOfDataFromDb = getDataFromDb();

        final List<String> someDataRetrievedIds = listOfDataFromDb.stream().map(SomeData::getId).collect(Collectors.toList());
        final Map<String, Boolean> someDataIdMapping = getVerificationFromExternalSystem(someDataRetrievedIds)
                .stream().collect(Collectors.toMap(SomeDataVerification::getId, SomeDataVerification::isOk));

        final List<SomeData> verifiedSomeData = listOfDataFromDb.stream().filter(eachData -> someDataIdMapping.getOrDefault(eachData.getId(), false))
                .collect(Collectors.toList());
        final Map<String, SomeData2> idAdditionalDataMapping = getVerifiedAdditionalData(verifiedSomeData);

        final List<SomeDataFull> mergedFullData = verifiedSomeData.stream().map(eachData -> {
            final var someData2 = idAdditionalDataMapping.get(eachData.getId());
            return SomeDataFull.builder()
                    .id(eachData.getId())
                    .email(someData2.getEmail())
                    .extraData(someData2.getExtraData())
                    .fileNumber(someData2.getFileNumber())
                    .whateverStuff(eachData.getWhateverStuff())
                    .build();
        }).collect(Collectors.toList());

        return mergedFullData;
    }

    public List<SomeDataFull> methodWithProperAbstraction() {
        final List<SomeData> verifiedSomeData = getVerifiedSomeData();
        final Map<String, SomeData2> idAdditionalDataMapping = getVerifiedAdditionalData(verifiedSomeData);
        final List<SomeDataFull> mergedFullData = mergeSomeDataAndAdditional(verifiedSomeData, idAdditionalDataMapping);

        return mergedFullData;
    }

    private Map<String, SomeData2> getVerifiedAdditionalData(List<SomeData> verifiedSomeData) {
        final List<String> someDataVerifiedIds = verifiedSomeData.stream().map(SomeData::getId).collect(Collectors.toList());
        return getAdditionalData(someDataVerifiedIds).stream()
                .collect(Collectors.toMap(SomeData2::getId, Function.identity()));
    }

    private List<SomeDataFull> mergeSomeDataAndAdditional(List<SomeData> verifiedSomeData, Map<String, SomeData2> idAdditionalDataMapping) {
        return verifiedSomeData.stream().map(eachData -> {
                final var someData2 = idAdditionalDataMapping.get(eachData.getId());
                return SomeDataFull.builder()
                        .id(eachData.getId())
                        .email(someData2.getEmail())
                        .extraData(someData2.getExtraData())
                        .fileNumber(someData2.getFileNumber())
                        .whateverStuff(eachData.getWhateverStuff())
                        .build();
            }).collect(Collectors.toList());
    }

    private List<SomeData> getVerifiedSomeData() {
        final List<SomeData> listOfDataFromDb = getDataFromDb();
        final List<String> someDataRetrievedIds = listOfDataFromDb.stream().map(SomeData::getId).collect(Collectors.toList());
        final Map<String, Boolean> someDataIdMapping = getVerificationFromExternalSystem(someDataRetrievedIds)
                .stream().collect(Collectors.toMap(SomeDataVerification::getId, SomeDataVerification::isOk));
        return listOfDataFromDb.stream().filter(eachData -> someDataIdMapping.getOrDefault(eachData.getId(), false))
                .collect(Collectors.toList());
    }