Optional value should only be accessed after calling isPresent()

Question

How can I change my code according to Sonar lint rules?

My code is below:

public interface TokenParser {
    public Optional<String> getUserName();
}

public class JWTTokenParser implements TokenParser {

    private Optional<Jwt> getJwt() {
        Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
        if (!authentication.isAuthenticated() || authentication instanceof AnonymousAuthenticationToken) {
            return Optional.empty();
        }
        return Optional.ofNullable((Jwt) authentication.getPrincipal());
    }

    @Override
    public Optional<String> getUserName() {
        return Optional.ofNullable(getJwt().get().getClaimAsString("preferred_username"));
    }
}

I could not pass the Sonar rules. How can I change my code?

Does this answer your question? ['Optional.get()' without 'isPresent()' check](https://stackoverflow.com/questions/38725445/optional-get-without-ispresent-check) — HariHaravelan, Apr 15 '22 at 14:38

samabcde · Accepted Answer · 2022-04-15T15:22:59.560

The problem is warning about the get is called without checking isPresent. Which will throw NoSuchElementException if no value is present, it violates the idea of using Optional.

    @Override
    public Optional<String> getUserName() {
        return Optional.ofNullable(getJwt().get().getClaimAsString("preferred_username"));
    }

Since getUserName() is also returning an Optional, we may use Optional#map to convert Optional<Jwt> to Optional<String>

 return getJwt().map(jwt -> jwt.getClaimAsString("preferred_username")));

map method will take care different case for us, as below:

getJwt()	jwt.getClaimAsString("preferred_username")	return
empty	will not call	Optioal.empty()
empty	will not call	Optioal.empty()
not empty	return null	Optioal.empty()
not empty	return non null value	Optional with non null value

Optional value should only be accessed after calling isPresent()

1 Answers1