OOP

What are the 4 principles of OOP?

• Encapsulation

• Abstraction

• Inheritance

• Polymorphism

What is Encapsulation?

Encapsulation is bundling data (properties) and methods that operate on that data into a single unit (class) and restricting direct access to some of the object’s components.

Why is Encapsulation important?

• Protects data

• Prevents unintended modification

• Improves maintainability

• Controls access using public/private/protected

What is Abstraction?

Abstraction is hiding complex implementation details and exposing only the essential features of an object.

How is Abstraction achieved?

• Interfaces

• Abstract classes

• Public APIs

What is Inheritance?

Inheritance allows a class (child) to acquire properties and methods of another class (parent).

Why use Inheritance?

• Code reuse

• Logical hierarchy

• Easier maintenance

• Extending existing behavior

What is Polymorphism?

Polymorphism means “many forms” — the same method can behave differently depending on the object that calls it.

Types of Polymorphism

• Method overriding (runtime)

• Method overloading (compile-time, in some languages)

Real-world example of Polymorphism

A draw() method:

• Circle → draws a circle

• Square → draws a square