Data Structures and Algorithms
with Object-Oriented Design Patterns in Java 
Encapsulation aids the software designer by enforcing information hiding. Objects encapsulate data and the procedures for manipulating that data. In a sense, the object hides the details of the implementation from the user of that object.
There are two very real benefits from encapsulation--conceptual and physical independence. Conceptual independence results from hiding the implementation of an object from the user of that object. Consequently, the user is prevented from doing anything with an object that depends on the implementation of that object. This is desirable because it allows the implementation to be changed without requiring the modification of the user's code.
Physical independence arises from the fact that the behavior of an object is determined by the object itself. The behavior of an object is not determined by some external entity. As a result, when we perform an operation on an object, there are no unwanted side-effects.
Copyright © 1998 by Bruno R. Preiss, P.Eng. All rights reserved.