Remove objects from a List based on their path

February 16, 2023

I have two lists:

private final List<EventTeaserModel> events = new ArrayList<>();
private final List<EventTeaserModel> premiumEventList = new ArrayList<>();

The use case for my method removePremiumEventsFromEvents() is to remove premiumEventList objects from the events List (remove objects with the same path).

Here is what I tried and it works. Is there a better way to do it in Java?

private void removePremiumEventsFromEvents() {
            for (EventTeaserModel premiumEvent: premiumEventList) {
                List<EventTeaserModel> findDuplicatedEvent = events.stream()
                        .filter(event -> event.getResource().getPath().equals(premiumEvent.getResource().getPath()))
                        .collect(Collectors.toList());
                events.removeAll(findDuplicatedEvent);
            }
        }

Thanks to @Chaosfire I was able to simplify it like:

private void removePremiumEventsFromEvents() {
        for (EventTeaserModel premiumEvent : premiumEventList) {
            events.removeIf(event -> event.getResource().getPath().equals(premiumEvent.getResource().getPath()));
        }
    }

>Solution :

This solution is kinda similar to yours conceptually, but it looks a bit cleaner.
You can first find all paths in premiumEventList, then use removeIf on events for each of the paths. Like this:

private void removePremiumEventsFromEvents() {
    premiumEventList.stream()
        .map(EventTeaserModel::getResource)
        .map(Resource::getPath)
        .forEach(path -> events.removeIf(event -> 
            event.getResource().getPath().equals(path)));
}

Personally however, I like to keep my lists unmodifiable/immutable. So I would instead create a new events list with the elements filtered. Like this:

private void removePremiumEventsFromEvents() {
    final Set<String> paths = premiumEventList.stream()
        .map(EventTeaserModel::getResource)
        .map(Resource::getPath)
        .collect(Collectors.toSet());

    // Or preferrably, return the new list.
    events = events.stream()
        .filter(event -> !paths.contains(event.getResource().getPath()))
        .collect(Collectors.toList());
}