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import java.util.concurrent.ConcurrentHashMap;public class Factory {	private ConcurrentHashMap
   
     registedList = new ConcurrentHashMap
    
     ();	public void register(String name,Object object) {		registedList.put(name, object);	}		private static Factory factory = null;		public Vehicle createSpecifiedVehicle(String name) {		return ((Vehicle)registedList.get(name)).createObject();		/*This is not gonna work as when createSpecifiedVehicle is called the static blocks in sub-classes has not been 		 * executed yet so registedList is actually empty.Static block in a class will be executed at the time the class		 * is being load,and only when the class is needed it will be loaded by ClassLoader.*/	}		public static Factory getInstance() {		if( null == factory ) {			synchronized(Factory.class) {				if( null == factory ) {					factory = new Factory();				}			}		}				return factory;	}}
    
   

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