for stackoverflow.com/questions/70689

class Bar {
    private static class BarHolder {
        static {
            System.err.println("BarHolder initialization");
        }
        public static Bar bar = new Bar();
    }

    public static Bar getBar() {
        return BarHolder.bar;
    }


    public Bar() {
        System.err.println("complex Bar ctor running");
    }


    public static void main (String[] args) {
        System.err.println("fetching a Bar");
        Bar some_bar = Bar.getBar();
        System.err.println("fetching another Bar");
        Bar another_bar = Bar.getBar();
        System.err.println("done");
    }
}

/*
Running with "java Bar" :
fetching a Bar
BarHolder initialization
complex Bar ctor running
fetching another Bar
done


Running with "java -verbose:class Bar" :
[...several hundred lines of JRE loading...]
fetching a Bar
[Loaded Bar$BarHolder from file:/C:/src/]  <-- delayed loading
BarHolder initialization
complex Bar ctor running
fetching another Bar
done
[Loaded java.lang.Shutdown from C:\....\rt.jar]
[Loaded java.lang.Shutdown$Lock from C:\....\rt.jar]

*/