SOLID Principles Guide

Five OOP design principles explained

SOLIDOOPArchitecture

The Principles

S — Single Responsibility

A class should have only one reason to change. One job, one class.

O — Open/Closed

Open for extension, closed for modification. Use interfaces and inheritance.

L — Liskov Substitution

Subtypes must be substitutable for their base types. Don't break expectations.

I — Interface Segregation

Don't force clients to depend on interfaces they don't use. Keep interfaces small.

D — Dependency Inversion

Depend on abstractions, not concretions. Use dependency injection.