Re: Singleton Pattern

People have been coming up with creative solutions to lazily implement
the singleton pattern in a thread-safe way. We have seen things like
double-checked locking and creating instance via a single-elemnt enum
type.

I have thought of yet another way to implement this in a lazy and
thread-safe way. I haven't seen this proposed anywhere and it seems to
work unless I am missing something. Here it goes:

public class Singleton {

        private static Singleton _instance;
        private Singleton(){}

        private synchronized static void createInstance(){
                _instance = new Singleton();
        }

        public static Singleton getInstance(){
                if (_instance == null){
                        createInstance();
                }
                return _instance;
        }

}

The synchronized createInstance() method would eliminate the need to
do double-checked locking and the synchronization would happen only
when multiple threads call getInstance() before _instance has been
instantiated.

Anyone see any issues with this?