Singleton lazy vs eager instantiation

Question

If a singleton is implemented as follows,

class Singleton {
    private static Singleton instance = new Singleton();

    public static Singleton getInstance         


        

Answer 1

For the reasons you mention, this is just a more complicated way of doing much the same as

enum Singleton {
    INSTANCE;
}

Using lazy initialisation is only useful if you are concerned that the class could be initilised but you don't want to load the singleton at that point. For most situations this is over kill.

Note: Just referencing the class does not initialise the class.

e.g. Say you have a badly written class which cannot be initilised until some condition is set. In this case n must be non-zero.

public class Main {
    public static void main(String ... args) {
        Class c= LazyLoaded.class;
        System.out.println(c);
    }

    static class LazyLoaded {
        static int n = 0;
        static {
            System.out.println("Inverse "+1000/n);
        }
    }
}

prints

class Main$LazyLoaded