10 Interview questions on Singleton Pattern in Java

If you really need a lazy Java singleton for some reason, letting the classloader construct it (guaranteed to happen at most once, and as late as possible) is effortless and more robust than screwing around with the synchronization yourself. On the other hand, interviewing candidates has so shaken my faith that I'd be very impressed to meet anyone who knew this.

http://en.wikipedia.org/wiki/Singleton_pattern#The_solution_...

Most of these are trivial or just generic threadsaftey questions.

You probably should not be using the singleton pattern in the first place though, global state is not an elegant solution.