객체안 값을 비교하여 sort Collections sort

Collections.sort(list, new Comparator<SomeDto>() {
   @Override
   public int compare(SomdDto o1, SomeDto o2) {
      return o1.getCreatedAt().compareTo(o2.getCreatedAt());
   }
});

객체안 값을 비교하여 sort Collections sort