java : get count of all distinct keys and values in Map<String,Set<String>>

Question

This question already has answers here: question from:https://stackoverflow.com/questions/65897828/java-get-count-of-all-distinct-keys-and-values-in-mapstring-setstring

Answer 1

You can do something like this:

Set<String> o = m1.entrySet()
                  .stream()
                  .flatMap(e -> Stream.concat(Stream.of(e.getKey()),e.getValue().stream()))
                  .collect(Collectors.toSet());

i.e. create a Stream<String> of each entry of the Map.