changes

gistfile1.txt

Here are some potential improvements to the provided code:

    Descriptive Naming: Improve the method and variable names to be more descriptive, making the code more self-explanatory.

    Reduce Nesting: The deep nesting in the lambda within the forEachExisting can be simplified for better readability.

    Method Decomposition: Breaking down the lambda function can help improve readability and maintainability.

Let's apply these improvements:

java

public void processSegmentsOfCondition(ConditionEntity conditionEntity) {
    forEachInCollection(conditionEntity.getSegmentSet(), this::handleRelation);
}

public void handleRelation(Relation relation) {
    reconcileSegmentWithDatabase(relation);
    setRelationIdFromConditionSegment(relation, conditionEntity);
}

private void reconcileSegmentWithDatabase(Relation relation) {
    Segment segment = relation.getSegment();
    Segment reconciledSegment = fetchFromDbOrElseSave(segment, segment::getName, segmentRepository::findByName, segmentRepository::save);
    relation.setSegment(reconciledSegment);
}

private void setRelationIdFromConditionSegment(Relation relation, ConditionEntity conditionEntity) {
    Optional.ofNullable(relation.getSegment().getConditionSegments())
        .flatMap(relations -> relations.stream()
                .filter(existingRelation -> Objects.equals(existingRelation.getCondition().getId(), conditionEntity.getId()))
                .findFirst()
                .map(ConditionSegmentEntity::getId))
        .ifPresent(relation::setId);
}

public static <T> void forEachInCollection(Collection<T> collection, Consumer<? super T> action) {
    Optional.ofNullable(collection).ifPresent(coll -> coll.forEach(action));
}

private <T, X> T fetchFromDbOrElseSave(T entity, Supplier<X> identifierSupplier, Function<X, Optional<T>> dbFetcher, Function<T, T> dbSaver) {
    return Optional.ofNullable(entity)
        .map(unused -> dbFetcher.apply(identifierSupplier.get())
                .orElseGet(() -> dbSaver.apply(entity)))
        .orElse(null);
}

Changes made:

    forEachExisting was renamed to forEachInCollection for clarity.

    Broke down the large lambda into two separate methods: handleRelation and reconcileSegmentWithDatabase.

    Renamed ifDbHasItOrElseSave to fetchFromDbOrElseSave for a clearer intent.

    Introduced a new method setRelationIdFromConditionSegment to handle the ID setting logic, making the main process more readable.

    Used the more generic Collection in forEachInCollection.

    Changed the method and variable names to make their purpose more evident.

With these changes, the code should be more maintainable and easier to understand.