Tài liệu The Purpose of Encapsulation pptx

The Purpose of Encapsulation
Encapsulation is an important principle when defining classes. The idea is that a program
that uses a class should not have to worry how that class actually works internally; the
program simply creates an instance of a class, and calls the methods of that class. As long
as those methods do what they say they will do, the program does not care how they are
implemented. For example, when you call the Console.WriteLine method, you don't want
to be bothered with all the intricate details of how the Console class physically arranges
for data to be output to the screen. A class might need to maintain all sorts of internal
state information in order to perform its various methods. This additional state
information and activity is hidden from the program that is using the class. Therefore,
encapsulation is sometimes referred to as information-hiding. Encapsulation actually has
two purposes:
1. To combine methods and data inside a class; in other words, to support
classification.
2. To control the accessibility of the methods and data; in other words, to control the
use of the class.