Паттерн: Одиночка (Singleton)
Фрагмент: SingletonSub, через стат-инициализатор [java] 
  1. package singleton;
  2.  
  3. public class SingletonSub extends RegSingleton {
  4. 	// It's the only time and place when
  5. 	// its constructor invokes
  6. 	static {
  7. 		new SingletonSub();
  8. 	}
  9.  
  10. 	protected SingletonSub() {
  11. 		// put this subclass in common register with
  12. 		// this class name
  13. 		RegSingleton.Register(this.getClass().getName(), this);
  14. 	}
  15.  
  16. }