001package headfirst.singleton.subclass;
002
003public class Singleton {
004        protected static Singleton uniqueInstance;
005
006        // other useful instance variables here
007
008        protected Singleton() {}
009
010        public static synchronized Singleton getInstance() {
011                if (uniqueInstance == null) {
012                        uniqueInstance = new Singleton();
013                }
014                return uniqueInstance;
015        }
016
017        // other useful methods here
018}