很老但是很经典的线程保险的LazyLoading单例

很老但是很经典的线程安全的LazyLoading单例

static class SingletonHolder {
  static Singleton instance = new Singleton();    
}

public static Singleton getInstance() {
  return SingletonHolder.instance;
}

http://blog.crazybob.org/2007/01/lazy-loading-singletons.html