OnDemandSingleton.java

public class OnDemandSingleton {
    private OnDemandSingleton() { }

    private static class OnDemandSingletonHolder {
        public static final OnDemandSingleton instance = new OnDemandSingleton();
    }

    public static OnDemandSingleton getInstance() {
        return OnDemandSingletonHolder.instance;
    }
}