Object-Oriented Programming Interview Questions

OOP is a programming paradigm based on objects and classes that supports encapsulation, inheritance, polymorphism, and abstraction.

A class is a blueprint for creating objects containing attributes and methods.

An object is an instance of a class that contains data and behavior.

Encapsulation is restricting access to internal data and allowing modification only through methods.

Inheritance allows a class to acquire properties and methods of another class.

Polymorphism allows methods to have different behaviors based on the object.

Abstraction hides implementation details and shows only essential features.

Single, multiple, multilevel, hierarchical, and hybrid inheritance.

Method overriding occurs when a child class provides a specific implementation of a parent method.

Python does not support traditional method overloading but can simulate it using default arguments.

self refers to the current instance of a class.

Constructor is __init__ method used to initialize objects.

super() is used to call parent class methods.

Multiple inheritance allows a class to inherit from more than one parent class.

Follow release notes, RFCs or PEPs, official blogs, and reputable courses. Experiment in side projects when new Object-Oriented Programming-related features ship so you can speak confidently about migration paths.

Name concrete modules (collections, itertools, pathlib, typing) and how they support Object-Oriented Programming. Prefer stdlib before third-party when it is enough.

Explain the classic default-list bug and closures in loops. Show a safe pattern when Object-Oriented Programming uses defaults or lambdas.

pytest with fixtures, parametrize, and coverage. Mock I/O at boundaries so Object-Oriented Programming unit tests stay deterministic.

Annotate public APIs, use mypy/pyright in CI, and prefer Protocols for duck typing. Catch Object-Oriented Programming contract breaks before runtime.

Generators save memory for large streams; comprehensions are clear for small transforms. Justify the choice for Object-Oriented Programming data sizes.