[Java]Optional 관련

   public Optional<Member> findByLoginId(String loginId){
        List<Member> all = findAll();
        for (Member m : all) {
            if (m.getLoginId().equals(loginId)) {
                return Optional.of(m);
            }
        }
        return Optional.empty();
    }

• 람다식 사용

    return findAll().stream()
           .filter(m -> m.getLoginId().equals(loginId)).findFirst();

---

 Optional<Member> optional = memberRepository.findByLoginId(loginId);
 Member member = optional.get();
if (member.getPassword().equals(password)) {
    return  member;
} else {
    return null;
}

• 람다식 사용

return memberRepository.findByLoginId(loginId)
	.filter(m -> m.getPassword().equals(password))
    .orElse(null);