interviewer: “You have 2 minutes. Explain all 7 of OOPS concepts to me.” My answer: Challenge accepted, Let’s go.


 1️⃣ Encapsulation

-  Bundles data and methods in a single unit.

-  Protects data from outside interference and misuse.


Example: A class `Car` with private attributes like `speed` and `fuel`, and public methods like `accelerate` and `brake`.


 2️⃣ Abstraction

-  Hides complex implementation details, exposing only the necessary information.

-  Simplifies code interaction and reduces complexity.


Example: A `Database` interface with methods `connect` and `query`, hiding the details of SQL or NoSQL operations.


 3️⃣ Inheritance

-  Allows a class to inherit properties and behaviors from another class.

-  Promotes code reuse and reduces redundancy.


Example: A `Vehicle` class inherited by `Car` and `Bike` classes, sharing common properties like `engine` and methods like `start`.


 4️⃣ Polymorphism

-  Objects of different types can be treated as the same type.

-  Enables flexible and modular code.


Example: A method `draw` that can work with objects of `Circle`, `Square`, and `Triangle` classes.


 5️⃣ Composition

-  Combines simpler objects to create complex ones.

-  Enhances code maintainability and flexibility.


Example: A `House` class composed of `Room` objects like `Kitchen`, `Bedroom`, and `Bathroom`.


 6️⃣ Association

-  Relationship between two objects where one uses or depends on the other.

-  Defines how objects interact with each other.


Example: A `Library` class is associated with `Book` class where the library contains books.


 7️⃣ Dependency Inversion

-  High-level modules should not depend on low-level modules;

-  both should depend on abstractions.

-  Reduces coupling between code and enhances flexibility.


Example: A `PaymentProcessor` class depends on an `IPaymentGateway` interface instead of concrete implementations like `Paypal` or `Stripe`.


posted by Ishmeet Singh Sethi