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  • Java设计模式(四) 单例模式

    方式一
    package com.pattern.Singleton;
    
    public class Singleton {
    	
    	private static Singleton uniqueInstance;
    	
    	private Singleton(){}
    	
    	public static Singleton getInstance(){
    		if(uniqueInstance == null){
    			uniqueInstance = new Singleton();
    		}
    		return uniqueInstance;
    	}
    }
    


    方式二

    package com.pattern.Singleton;
    
    public class Singleton2 {
    	
    	private static Singleton2 uniqueInstance = new Singleton2();
    	
    	private Singleton2(){}
    	
    	public static Singleton2 getInstance(){
    		return uniqueInstance;
    	}
    }
    

    方式三

    package com.pattern.Singleton;
    
    public class Singleton3 {
    	
    	private volatile static Singleton3 uniqueInstance;
    	
    	private Singleton3(){}
    	
    	public static Singleton3 getInstance(){
    		if(uniqueInstance == null){
    			synchronized(Singleton.class){
    				if(uniqueInstance == null){
    					uniqueInstance = new Singleton3();
    				}
    			}
    		}
    		return uniqueInstance;
    	}
    }
    



     

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  • 原文地址:https://www.cnblogs.com/mengjianzhou/p/5986819.html
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