单例模式的写法和线程安全性的讨论

标签：单例模式   线程安全   

class Singleton1{
	private Singleton1(){}
	private static Singleton1 s1 = new Singleton1();
	public static Singleton1 getSingleton(){
		return s1;
	}
}

class Singleton2{
	private Singleton2(){}
	private static Singleton2 s2 = null;
	public static Singleton2 getSingleton2(){
		if(s2 == null){
			s2 = new Singleton2();
		}
		return s2;
	}
}

class Singleton3{
	private Singleton3(){}
	private static class SingleHolder{
		private final static Singleton3 s3 = new Singleton3();
	}
	
	public static Singleton3 getSingleton3(){
		return SingleHolder.s3;
	}
}

class Singleton4{
	private static Singleton4 s4= null;
	private Singleton4(){}
	public static synchronized Singleton4 getSingleton4(){
		if(s4 == null){
			s4 = new Singleton4();
		}
		return s4;
	}
}

单例模式的写法和线程安全性的讨论

标签：单例模式   线程安全   

原文地址：http://blog.csdn.net/simongeek/article/details/45245061