java singleton instantiation

Question

I\'ve found three ways of instantiating a Singleton, but I have doubts as to whether any of them is the best there is. I\'m using them in a multi-threaded environment and pr

Answer 1

The most secure and easy way to implement a singleton in java is by using enums (like you mentioned):

public enum ClassName {
    INSTANCE;

    // fields, setters and getters
}

The enum semantics guarantees that there will be only one INSTANCE

If not using the enum approach, you must take care of quite a lot aspects, like race conditions and reflection. I've been breaking singletons of some frameworks, and abusing them, because they weren't properly written. The enum guarantees no one will break it.