Design Patterns: Creational

Master Singleton, Factory, Builder patterns that control object creation, enabling flexible, testable systems

70 minutes

5Detailed Sections

Senior Level

Creational patterns solve the problem: How do we create objects in a way that makes code flexible and testable? Direct instantiation couples client code to concrete classes, making testing hard and changes risky.

Creational patterns use abstraction to decouple creation logic from usage. Real-world: Netflix services don't directly create PaymentClient; factories do.

Databases use DriverManager factory to return appropriate driver (PostgreSQL, MySQL) without client knowing. Testing is the core driver: mocking creation lets you test PaymentProcessor without real payments.

This section motivates patterns through testability and scalability.

Key Takeaways

Tight coupling: Client code creates objects directly = hard to test and change

Solution: Abstract object creation via factories, builders, singletons

Testability: Can inject mock factory to control object creation

Flexibility: Change which objects created without touching client code

Scalability: Consistent creation logic across services (Netflix, AWS)

Most common: Factory (used everywhere), Singleton (careful), Builder (optional params)

Visual Diagram

Direct Creation (tight) -> Factory (decoupled) -> Builder (fluent) -> Singleton (global)

All Tutorials Practice Questions

Design Patterns: Creational

Table of Contents

Creational Patterns: Why Object Creation Matters

Key Takeaways

Visual Diagram

Factory Pattern: Delegating Creation Logic

Singleton Pattern: One Global Instance

Builder Pattern: Fluent Object Construction

Real-World Applications: Factories and Builders at Scale