시그마 삽질==six 시그마

List list = null; //error list.stream().filter(Objects::nonNull).forEach(v -> System.out.println(v.getUsername())); //ok CollectionUtils.emptyIfNull(list).stream() .filter(v -> v.getUsername().equals("foo")) .collect(Collectors.toList()); //ok Optional.ofNullable(list) .orElseGet(Collections::emptyList).stream() .filter(v -> v.getUsername().equals("boo")) .collect(Collectors.toList()); 1.Null 자체..