“Java Clump List” Ответ

Java Clump List

int[] arr = new int[]{3, 4, 5, 5, 5, 6, 2, 2};

IntStream.of(arr)
  .filter(data -> Collections.frequency(Arrays.asList(arr), data) > 1)
  .distinct()
  .forEach(data -> { System.out.println(data); } );