This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
Singleton is merely a Design Pattern. Implementations can vary greatly, especially among languages. In Java, a Singleton is typically implemented with a public static method that maintains and returns a single instance of the class. The construction of the class outside this static method is forbidden by setting the acessibility level of the Constructor to private. Example: