What is an efficient way to implement a singleton pattern in Java

Question

Please help!

Answer 1

Use an enum:

public enum Foo 

{
    INSTANCE;
}

The Right Way to Implement a Serializable Singleton

public enum Elvis {
    INSTANCE;
    private final String[] favoriteSongs =
        { "Hound Dog", "Heartbreak Hotel" };
    public void printFavorites() {
        System.out.println(Arrays.toString(favoriteSongs));
    }
}