How to exclude certain Enum type from stream?

Question

How can I exclude an enum named CodesType in this code ?

Code returns a list of objects of the EventsData class and I want to be able to skip one designated enum.

I would like to exclude an Enum named CodesType. By default it is added in the mapEvents variable which means that I would have to add some filtering there so that the Enum named CodesType is skipped. I just don't know how to implement correctly. I tried something like this, but it doesn't work .filter(type -> type != CodesType).

You can also see in the code that I manually add two EventsData objects such as CodesType and SupportType. Therefore, I want to exclude this CodesType object that is added at the beginning so that a duplicate is not created. (It has to exist because the objects I add manually are created based on it, but it doesn't have to be retrieved so I want to exclude it).

private List < EventsData > getEvents() {
    final List < EventsData > eventsList = eventListStream.stream()
        .map(mapEvents)
        .collect(Collectors.toList());
    eventList.add(new EventsData("CodesType", getCodesType()));
    eventList.add(new EventsData("SupportType", getSupportType()));
    return eventList;
)

Answer 1

You can use

private List<EventsData> getEvents() {
    final List<EventsData> eventList = eventListStream.stream()
        .filter(type -> type != CodesType.class)
        .map(events -> new EventsData(events.getSimpleName(), getType(events)))
        .collect(Collectors.toCollection(ArrayList::new));
    eventList.add(new EventsData("CodesType", getCodesType()));
    eventList.add(new EventsData("SupportType", getSupportType()));
    return eventList;
}

private String[] getType(Class<? extends Enum<?>> events) {
    return Arrays.stream(events.getEnumConstants())
        .map(Enum::name)
        .sorted()
        .toArray(String[]::new);
}

Instead of declaring a Function outside the Stream pipeline, I moved the complex part into a named method, which aligns with your already existing methods, getCodesType() and getSupportType().

Instead of collecting into a mutable list, to add the predefined elements, you can also integrate them into the Stream pipeline:

private List<EventsData> getEvents() {
    return Stream.concat(
        eventListStream.stream()
            .filter(type -> type != CodesType.class)
            .map(events -> new EventsData(events.getSimpleName(),getType(events))),
        Stream.of(new EventsData("CodesType", getCodesType()),
                  new EventsData("SupportType", getSupportType()))
    ).collect(Collectors.toList());
}