How to get optional values ​​from the map as an additional list?

Question

Map<Long, Optional<Long>> aMap = new HashMap<>();

This card has several keys and optional values.

Optional<List<Long>> valuesList = input.aMap().values().stream()
                            .collect(Collectors.toList());

The specified method has a compilation error. How to get an additional list?

Answer 1

you skip and return a value, do not forget that it Optional<List<Long>>is an optional object, which can have 1 list if it is present ....

you need instead List<Optional<Long>>

List<Optional<Long>> valuesList = input.aMap()
                   .values()
                   .stream()
                   .collect(Collectors.toList());

Answer 2

You don't even need to streamhere, just to put them together in List:

 List<Optional<Long>> list = new ArrayList<>(input.aMap().values());