CHAPTER 33 — Encapsulation

So far, the objects that we have designed have instance variables that are visible outside of the objects. Any code that holds a reference to an object can change the object's instance variables. This is often leads to problems.

A better design enforces encapsulation. Some (or all) of an object's instance variables are visible only to the object's own methods. Code outside of the object cannot access these variables directly. This chapter discusses how to use the private visibility modifier to do this.

Chapter Topics:

• The private and the public visibility modifiers
• Default visibility
• Encapsulation
• Access methods
• Further enhancement of the CheckingAccount class