// "Replace with lambda" "true" import java.util.Map; import java.util.function.Function; import java.util.stream.Collectors; import java.util.stream.Stream; class Test { private static final Map<String, Mood> WORD_TO_MOOD = null; public static void analyseMood(String[] wordsInMessage) { Stream.of(wordsInMessage) .map(s -> WORD_TO_MOOD.get(s)) .filter(mood -> mood != null) .collect(Collectors.toSet()); } enum Mood {} }