Well, it's part of the spirit: you create hand-crafted solutions to learn from people who just know how to avoid reinventing the wheel. After all, the more you practice, the better you become.

I don't think this null is necessary for this problem.

@davorpa If you read the docs, it shows that has the null check built into it.

if (locale == null) {
throw new NullPointerException();
}

do you know the concept of null-safe methods? null is not same as empty

It's no need to check for empty string, because .toUpperCase contains this condition: https://www.javatpoint.com/java-string-touppercase

Me too! First try! Am I getting... better at this??

As a Java newbie, I was really impressed by this solution cause of it only takes 1 row. Nice:)

Don't get discouraged, I think it's good if you're able to write your own method.
Also now you've learned how to solve this challenge in another way. It's a win-win situation.

Seeing this immediately after my attempt made a single, cold, salty tear fall from my eye.