How to write a Singleton in proper manner?

Question

Today in my interview one interviewer asked me to write a Singleton class. And i gave my answer as

public class Singleton {

    private static Singleton re         


        

Answer 1

The Singleton I'd write would look like this:

@Service
class PersonService {
    // implementation here
}

But I also like the enum ideas. In reality, I never write (nor need) a Singleton other than one like the one above.