Class Anatomy

Data Encapsulation

Data encapsulation is the practice of keeping an object's data together with the methods that work with that data. It also allows a class to control how its data is accessed and modified.

One way Java supports encapsulation is through access modifiers, such as public and private.

Using encapsulation helps protect an object's data and makes classes easier to maintain.

Access Modifiers

An access modifier determines where a class, field, constructor, or method can be accessed.

The two most common access modifiers are:

• public: A public member can be accessed from anywhere that the class is visible.
• private: A private member can only be accessed from within its own class.

In AP CSA, it is recommended to use private for:

• instance variables
• methods that can only be accessed internally to the class

In AP CSA, it is recommended to use public for:

• class headers
• constructors
• methods that can be accessed internally or externally

Benefits of Encapsulation

Encapsulation helps you:

• protect an object's data from unintended changes
• ensure data remains valid
• hide implementation details from other classes
• make classes easier to maintain and modify

By controlling how data is accessed, you can change the implementation of a class without affecting the code that uses it.

Choosing Between public and private

As a general guideline:

• Use private for fields that store an object's data.
• Use public for constructors and methods that other classes should be able to use.
• Only expose the functionality that other classes need.

This approach helps keep objects in a valid state while providing a clear interface for interacting with them.