Tell me about a time you helped a team member who was struggling.

// SITUATION: Teammate kept getting NullPointerException
// when calling userRepository.findById() in their service

// Their original code:
public User getUserDetails(Long userId) {
    User user = userRepository.findById(userId).get();
    return user;  // NPE when user doesn't exist
}

// What I did: Instead of just fixing it, I explained
// the problem using their code as the example

// STEP 1: Showed them why it breaks
var result = userRepository.findById(999L);  // non-existent ID
System.out.println(result.isPresent());      // prints: false
// result.get();  // calling get() here throws NoSuchElementException

// STEP 2: Explained Optional<T> concept from JDK 8+
// "findById returns Optional because the user might not exist.
// Optional is Java's way of forcing you to handle the missing case."

// STEP 3: Showed them three proper ways to handle it

// Option A: Throw exception with clear message
public User getUserDetails(Long userId) {
    return userRepository.findById(userId)
        .orElseThrow(() -> new UserNotFoundException(
            "User not found with id: " + userId));
}

// Option B: Return null and let controller handle it
public User getUserDetails(Long userId) {
    return userRepository.findById(userId).orElse(null);
}

// RESULT: They understood Optional and started using it
// correctly in other methods. They taught it to another
// teammate later, which showed they truly got it.