Initialization-on-demand holder idiom

     
    package me.dhanoop.singleton;

    /**
     *
     * @author dhanoopbhaskar
     */
    public class Singleton {

        private static class HelperHolder {

            public static Helper helper = new Helper();
        }

        public static Helper getHelper() {
            return HelperHolder.helper;
        }

        public static void main(String[] args) {

            Runnable runnable = new Runnable() {

                @Override
                public void run() {
                    Singleton.getHelper();
                }
            };

            new Thread(runnable).start();
            new Thread(runnable).start();
            new Thread(runnable).start();
        }
    }