Low Level Design
How the Abstract Factory pattern ensures product families stay consistent and eliminates the risk of mixing incompatible objects at compile time.
How the Builder pattern eliminates telescoping constructors, keeps object construction readable, and enables immutable objects with optional fields.
How the Factory Method pattern eliminates scattered `new` calls, enforces the Open/Closed Principle, and keeps object creation logic in one place.
A deep dive into the Singleton design pattern: why it exists, common pitfalls, and three progressively better thread-safe implementations.