Java How to Program, Early Objects, 11th Edition

...  7	public static void main(String[] args)
8	{
9		Singleton firstSingleton;
10		Singleton secondSingleton;
11
12		// create Singleton objects
13		firstSingleton = Singleton.getInstance();
14		secondSingleton = Singleton.getInstance();
15
16		// the "two" Singletons should refer to same Singleton
17		if (firstSingleton == secondSingleton)
18			System.err.println("firstSingleton and secondSingleton " +
19			"refer to the same Singleton object");
20	} // end main
21 } // end class SingletonTest

N.2-1 Full Alternative Text

N.2.2 Structural Design Patterns

Structural design patterns describe common ways to organize classes and objects in a system. The Gang-of-Four ...