Encapsulation in Object-oriented Programming ( OOP)

What is encapsulation?

Encapsulation in OOP groups data and methods within a class to provide a protective barrier over internal implementation details. It allows the construction of objects that encapsulate data and reveal only the methods or interfaces required for interaction with the outside world. This method encourages information concealment by prohibiting direct access to an object's internal state.

Example 1: Encapsulation in C++

Consider the following example to grasp encapsulation in practice better. Assume we're creating a banking system and need a class representing a bank account. We want to encapsulate the account balance and give ways for depositing, withdrawing, and retrieving it.

In this example, the account balance is encapsulated by making it private and restricting direct access. Public methods, such as deposit(), withdraw(), and getBalance(), are used to safely modify and retrieve the balance while ensuring data integrity and security. These methods control the interaction with a BankAccount object, preventing unauthorized modifications or direct access to the balance.

Encapsulation is crucial in object-oriented programming as it enhances code security, modularity, and maintainability. It enables controlled access to object members, protects the internal state, and promotes code reusability by grouping data and behavior within a class. Embracing encapsulation empowers developers to create robust, secure, and maintainable code in the realm of OOP.

Benefits of encapsulation programming

Encapsulation in OOP is a vital feature in object-oriented programming (OOP) that combines data and operations into objects. It provides several benefits for software systems, including improved efficiency, maintainability, and security. Here are the key advantages of encapsulation programming:

• Data Protection and Security: Encapsulation in OOP hides internal details of an object and only exposes relevant information through well-defined interfaces. This safeguards data and restricts unauthorized access, enhancing system security and minimizing data corruption.
• Modularity and Reusability: Encapsulation in OOP promotes modularity and reusability by isolating internal implementation details from the external environment. Objects can be reused in different parts of a program or even across separate programs, reducing development time and effort.
• Code Maintainability: Encapsulation in OOP simplifies code maintenance by separating internal implementation from the external interface. Changes to the internal code won't affect how the object is used externally, making it easier to modify or improve the internal code without impacting external code.
• Information Hiding: Encapsulation in OOP enables the hiding of extraneous data and exposing only essential information to the outside world. By managing access levels and using designated methods, developers can control data manipulation, enhancing code readability and avoiding unwanted consequences.
• Code Flexibility and Extensibility: Encapsulation in OOP enhances code flexibility and extensibility by providing a clear and well-defined interface for object interaction. The internal implementation of an object can change without affecting the code using it, allowing for easy addition or modification of features.

How is information hidden via encapsulation programming?

Encapsulation in OOP, achieved through access modifiers and accessor/mutator methods, helps organize code and prevent accidental modifications. Access modifiers (public, private, and protected) control the visibility and accessibility of class members. Private members are limited to the class itself, while public members can be accessed anywhere. Protected members can be accessed within the class and its subclasses.

Accessor (getters) and mutator (setters) methods regulate data access and modification. Getters provide read-only access, while setters enable controlled data modification. Encapsulation in OOP ensures data integrity and prohibits direct tampering by enforcing controlled data access and modification.

By encapsulating data and operations in a class, code organization improves. Changes within the class won't affect the rest of the program as long as the public interface remains consistent. Encapsulation in OOP promotes code modularity and reusability, allowing developers to reuse encapsulated classes in different parts of their applications.

Encapsulation in Java

Consider a simple example of encapsulation in a Java class representing a Bank Account.

Explanation

This example's BankAccount class encapsulates the account number and balance data. The characteristics accountNumber and balance are private, limiting direct access from outside the class. To interact with the account, the class has public methods deposit, withdraw, and getBalance. These methods provide controlled access to the object's internal state.

Encapsulation in C++

Consider a practical example of encapsulation to demonstrate its application in C++. Assume we have a BankAccount class that represents a bank account with characteristics such as account number and balance. We want to ensure that the balance cannot be changed directly from outside the class.

Explanation

The member variables accountNumber and balance are marked as private in the preceding example, preventing direct access outside the class. Public member operations such as deposit, withdraw, and getBalance allow controlled account balance access. This encapsulation ensures that the account balance remains secure and can only be adjusted using the methods specified.

Types of encapsulations in OOPs

Object-Oriented Programming (OOP) is a popular programming paradigm in which data and functions are organized into objects. Encapsulation is a key principle of OOP that safeguards an object's internal state and enables controlled access to its data and behavior. In this section, we will look at several types of encapsulation in OOP and how they help to construct strong and maintainable code.

1. Access Modifiers:

Access modifiers specify how visible or accessible class members (attributes and methods) are from outside the class. Most OOP languages have three access modifiers: public, private, and protected.

• Public: Members of the public are available from any place in the program. Other classes, objects, or modules can access them. The visibility of general characteristics and methods is high.
• Private: Private members are only available within their declared class. They are inaccessible from outside the class. Private attributes and methods aid in encapsulating an object's internal state, prohibiting direct modification or access.
• Protected: Protected members are available within the class and its subclasses (derived classes). They must be reached from within the class hierarchy. When we wish to restrict access to specific areas of the code while still allowing inheritance and extension, we can use protected properties and methods.

Example:

2. Getters and Setters:

Getters and setters, often known as accessors and mutators, are methods for accessing and changing an object's private attributes. They offer controlled access to an object's internal state, allowing data validation or change before it is stored or retrieved.

• Getters: Getters are methods that fetch private attribute values. They are typically named getVariableName and return the value of the related attribute.
• Setters: Setters are methods that set or alter the values of private attributes. They are commonly named setVariableName and accept a parameter to apply a new value to the property.

Example:

Encapsulation in OOP can be enforced using getters and setters to ensure that all interactions with an object's attributes go through established methods. We control how data is accessed and modified in this manner, allowing for data validation or other business logic.

• Interfaces and Abstract Classes: Abstract classes and interfaces are used to construct contracts or blueprints for classes that implement or extend them. They allow for the simultaneous achievement of abstraction and encapsulation.
  • Interfaces: An interface is a collection of abstract methods that determine the behavior that classes that implement it must follow. By using interfaces, we can accomplish total abstraction and decouple implementation details from client code.
  • Abstract Classes: Abstract classes are only partially implemented and cannot be instantiated independently. They can provide concrete and abstract methods and serve as a model for derived classes. Encapsulation is enabled via abstract classes, which define a common interface for its subclasses while obscuring implementation details.

Example: