Encountering NullPointerException When Using Spring Data JPA with Optional Return Types
I can't seem to get I just started working with I'm working on a Spring Boot application using Spring Data JPA and I'm facing a `NullPointerException` when trying to fetch an entity using an `Optional`... I have a repository method that looks like this: ```java public interface UserRepository extends JpaRepository<User, Long> { Optional<User> findByUsername(String username); } ``` When I call this method in my service class, I expect it to return an empty `Optional` if the user does not exist. However, I am encountering a `NullPointerException` when I try to access the `User` object like this: ```java User user = userRepository.findByUsername(username).get(); ``` This is the stack trace I receive: ``` java.lang.NullPointerException: Cannot invoke "User.getUsername()" because "user" is null ``` To troubleshoot, I added logging to check the input and confirmed that the `username` passed is correct. I also checked the database and the user does not exist, which should lead to an empty `Optional`. Instead, it seems that `get()` is being called on a null value, resulting in the exception. I have tried using `isPresent()` to check if the user exists before calling `get()`, like this: ```java Optional<User> optionalUser = userRepository.findByUsername(username); if (optionalUser.isPresent()) { User user = optionalUser.get(); // Further processing } else { // Handle user not found } ``` This approach works, but I would prefer to handle this more elegantly. Is there a better way to handle the retrieval of an entity with an `Optional` without risking a `NullPointerException`? Perhaps a method to streamline this or best practices I should follow here? This is part of a larger application I'm building.