import java.util.Arrays; import java.util.List; import java.util.Map; import java.util.stream.Collectors; import java.util.stream.Stream; class IDEA118965 { { Stream<String> words = Arrays.asList("one", "one", "two").stream(); List<Map.Entry<String,Integer>> res = words.collect(Collectors.toMap(w -> w, w -> 1, (a, b) -> a + b)) .entrySet().stream().filter(e -> e.getValue() > 1).collect(Collectors.toList()); } }