Object Oriented Design

What is Method Overriding in OOP?

Method overriding is when a subclass provides its own implementation of a method already defined in its superclass, using the same name and signature.

What is Coupling and Cohesion in OOP?

Coupling measures how dependent one module or class is on another, while cohesion measures how strongly the responsibilities inside a single module belong toge…

What is the Observer Pattern?

The Observer pattern defines a one-to-many dependency where a subject notifies a list of registered observers automatically whenever its state changes.

What is a Virtual Function?

A virtual function is a member function declared in a base class that a derived class can override, with the actual implementation resolved at runtime based on…

Aggregation vs Composition in OOP

Aggregation and composition are both "has-a" relationships between objects, but composition implies strict ownership where the part cannot outlive the whole, w…

What is the Liskov Substitution Principle?

The Liskov Substitution Principle (LSP) states that objects of a subclass must be substitutable for objects of the base class without altering the correctness…

What is Multiple Inheritance?

Multiple inheritance is when a class inherits fields and methods from more than one parent class simultaneously, combining their behavior into a single subclas…

What is the Open-Closed Principle?

The Open-Closed Principle (OCP) states that software entities — classes, modules, functions — should be open for extension but closed for modification, meaning…

How to Design an Elevator System?

An elevator system is designed around a central dispatcher that models each car’s state (position, direction, queued stops) and assigns hall calls to the car t…

How to Design a Vending Machine System?

A vending machine system is best modeled as a finite state machine with a small set of explicit states (idle, selecting, awaiting payment, dispensing, returnin…