JAvaプログラミング問題:単一のスキーマを作成する

/**
 * java   ：         
 */
public class Singleton {

	/*
	//1.    ，   ,            。。。    new  ，    
	private Singleton(){}
	
	private static final Singleton Singleton = new Singleton();
	
	public static Singleton getInstance(){
		return Singleton;
	}
	*/
	
	/*
	//2.    ，      。。。      ，    ，    
	private Singleton(){}
	
	private static Singleton Singleton = null;
	
	public static Singleton getInstance(){
		if(Singleton==null){
			Singleton = new Singleton();
		}
		return Singleton;
	}
	*/
	
	/*
	//3.    ，    ，      。。。99%        
	private Singleton(){}
	
	private static Singleton Singleton = null;
	
	public static synchronized Singleton getInstance(){	//    synchronized  
		if(Singleton==null){
			Singleton = new Singleton();
		}
		return Singleton;
	}
	*/	
	
	/*
	//4.      
	private Singleton(){}
	
	//JDK5  ，             ，   volatile，           
	private static volatile Singleton Singleton = null;
	
	public static Singleton getInstance(){
		if(Singleton==null){
			synchronized(Singleton.class){		// synchronized     
				if(Singleton==null){
					Singleton = new Singleton();
				}
			}
		}
		return Singleton;
	}
	
	*/
	
	/*
	//5.      
	private Singleton(){}
	
	private static class SingletonHolder {
		private static final Singleton singleton = new Singleton();
	}
	
	public static final Singleton getInstance(){
		return SingletonHolder.singleton;
	}
	*/
	
	//6.   
	private static enum EnumSingleton{
        INSTANCE;
		
        private Singleton singleton;
        
        //JVM             
        private EnumSingleton(){
            singleton = new Singleton();
        }
        
        public Singleton getInstance(){
            return singleton;
        }
    }
	
}


  ：
http://cantellow.iteye.com/blog/838473
http://www.cnblogs.com/yinxiaoqiexuxing/p/5605338.html
http://blog.csdn.net/zhanlanmg/article/details/49944991