Java, C#, JavaScript三種語言實現單例模式

無論任何一門語言，模式的思想都一樣，不一樣的就是語言的細節。

Java版：

public class Singleton {
	private volatile static Singleton instance;
	private Singleton(){};
	
	public static Singleton getInstance()
	{
		if(instance == null){
			synchronized (Singleton.class) {
				if(instance == null){
					instance = new Singleton();
				}
			}
		}
		return instance;
	}
}

C#版：

public class Singleton  
{  
    protected Singleton() { }  
    private static volatile Singleton instance = null;  
    /// Lazy方式創建唯一實例的過程  
    public static Singleton Instance()  
    {  
        if (instance == null)           // 外層if  
            lock (typeof(Singleton))    // 多線程中共享資源同步  
                if (instance == null)   // 內層if  
                    instance = new Singleton();  
        return instance;  
    }  
}  

JS版：

var singletonTest=(function(){
    function single(args){
        var args=args || [];
        this.name='singletontest';
        this.x=args.x || 6;
        this.y=args.y || 7;
    };
    
    var instance;
    
    var _static={
    name:'singletontest',
    getInstance:function(args){
        if( instance === undefined)
        {
            instance = new single(args);
        }
        return instance;
    }
   };
   return -static;
})();

//調用 var singletonTest = SingletonTester.getInstance({ pointX: 5 });