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Design Patterns: Reusable Solutions for Scalable Systems

Overview

Design patterns are time-tested, reusable solutions to common software design problems, enabling modular, maintainable, and scalable code. In this hub, we cover all 23 Gang of Four (GoF) patterns — creational, structural, and behavioral — along with modern patterns like Dependency Injection, Repository, Event Sourcing, and CQRS.

By mastering these patterns, you’ll learn how to design elegant, extensible Java systems and apply them in real-world projects, from e-commerce platforms to distributed microservices.

Learning Objectives

  • Master creational patterns (e.g., Singleton, Factory, Builder, Prototype) for object creation.
  • Learn structural patterns (e.g., Adapter, Decorator, Proxy, Bridge, Composite, Flyweight, Facade) for object composition.
  • Apply behavioral patterns (e.g., Strategy, Observer, Command, State, Chain of Responsibility, Template Method, Mediator, Memento, Iterator, Interpreter, Visitor) for dynamic behavior.
  • Explore modern enterprise patterns (e.g., Dependency Injection, Repository, Event Sourcing, CQRS).
  • Design scalable systems using patterns, UML, and clean code.

Lessons

Introduction

  1. Introduction to Design Patterns (15 min)
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  2. Classification of Design Patterns (15 min)
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Creational Patterns (5 GoF)

  1. Singleton Pattern (15 min)
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  2. Factory Method Pattern (20 min)
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  3. Abstract Factory Pattern (20 min)
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  4. Builder Pattern (20 min)
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  5. Prototype Pattern (20 min)
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Structural Patterns (7 GoF)

  1. Adapter Pattern (15 min)
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  2. Decorator Pattern (20 min)
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  3. Facade Pattern (15 min)
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  4. Composite Pattern (20 min)
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  5. Proxy Pattern (20 min)
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  6. Bridge Pattern (20 min)
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  7. Flyweight Pattern (20 min)
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Behavioral Patterns (11 GoF)

  1. Strategy Pattern (20 min)
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  2. Observer Pattern (20 min)
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  3. Command Pattern (20 min)
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  4. Template Method Pattern (15 min)
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  5. State Pattern (20 min)
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  6. Chain of Responsibility Pattern (20 min)
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  7. Mediator Pattern (20 min)
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  8. Memento Pattern (20 min)
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  9. Iterator Pattern (15 min)
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  10. Interpreter Pattern (20 min)
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  11. Visitor Pattern (20 min)
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Modern Patterns

  1. Dependency Injection (20 min)
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  2. Repository Pattern (20 min)
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  3. Event Sourcing (20 min)
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  4. CQRS (Command Query Responsibility Segregation) (20 min)
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Capstone

  1. Mock Interview: Applying Patterns (30 min)
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Start Your Journey

Ready to build reusable, scalable systems with design patterns? Dive into Introduction to Design Patterns to begin, or explore other sections to continue your journey as a better software engineer.


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