Sams Teach Yourself Java in 21 Days (Covers Java 11/12), 8th Edition

Lesson 6. Packages, Interfaces, and Other Class Features

Classes, the templates used to create objects that can store data and accomplish tasks, turn up in everything you do with the Java language.

In this lesson, you’ll extend your knowledge of classes by learning more about how to create them, use them, organize them, and establish rules for how other classes can use them.

The following subjects are covered:

• Controlling access to methods and variables from outside a class

• Finalizing classes, methods, and variables so that their values or definitions cannot be overridden in subclasses

• Creating abstract classes and methods for factoring common behavior into superclasses

• Grouping classes into packages

• Using interfaces to bridge gaps in a class ...