Thread safety in Singleton

Question

I understand that double locking in Java is broken, so what are the best ways to make Singletons Thread Safe in Java? The first thing that springs to my mind is:

Answer 1

Josh Bloch recommends 2 solutions:

1) worser:

class Singleton {

   public static Singleton instance = new Singleton();

   ...
}

2) better:

public enum Singleton {

   INSTANCE;

   ...
}