OOD Interview Answer Flow

OOD Answer Flow

1. Clarify requirements
   Understand what the system needs to support.

2. Identify core classes
   Find the main objects in the system.

3. Define responsibilities + relationships
   Explain who is responsible for what and how classes connect.

4. Design key APIs / main flows Show the core methods and walk through the system flow.

5. Discuss extensibility + edge cases
   Explain how the system can scale or support future features.

4 Core Principles of OOP

1. Encapsulation

Bundle data and methods together inside a class, and hide internal details.

Example: A BankAccount keeps balance private and only allows access through deposit() or withdraw().

2. Abstraction

Expose only the necessary interface while hiding complex implementation details.

Example: You call payment.pay() without knowing how the payment system works internally.

3. Inheritance

Allow a child class to reuse properties and methods from a parent class.

Example: Car, Truck, and Motorcycle inherit from Vehicle.

4. Polymorphism

Allow the same method to behave differently for different objects.

Example: calculateFee() may work differently for Car and Truck.