Design Patterns Cheat Sheet: A Beginner-Friendly Guide
March 19, 2025 | by sabnisnayan99@gmail.com
What are Design Patterns?
Design patterns are proven solutions to common software design problems. Think of them as best practices that developers use to write efficient, scalable, and maintainable code. Instead of reinventing the wheel, you can apply these patterns to solve recurring challenges in software development.
Why Should You Care About Design Patterns?
- They make your code reusable and modular.
- They help in writing cleaner and more understandable code.
- They are widely used in the industry, making it easier to collaborate with other developers.
- They provide structured ways to handle object creation, behavior, and structure.
Types of Design Patterns
Design patterns are broadly categorized into three types:
- Creational Patterns – Focus on how objects are created.
- Structural Patterns – Define how different parts of a system work together.
- Behavioral Patterns – Manage object interactions and responsibilities.
Familiarize yourself with the Coffee Machine!
To make this guide intuitive, we’ll use a simple Coffee Machine example throughout. Imagine we’re designing a smart coffee machine that can brew different types of coffee, send notifications, and allows customization.
Overview of Design Patterns with Examples
| Category | Pattern | Simple Explanation |
|---|---|---|
| Creational | Singleton | Ensures only one instance of a class exists (e.g., one coffee machine controller). |
| Creational | Factory Method | Provides a way to create objects without specifying the exact class (e.g., different coffee types). |
| Structural | Adapter | Helps incompatible interfaces work together (e.g., a universal coffee pod adapter). |
| Structural | Decorator | Adds features dynamically without modifying the existing class (e.g., adding sugar, milk, or flavors to coffee). |
| Behavioral | Observer | Notifies multiple objects when an event occurs (e.g., notifying a mobile app when coffee is ready). |
| Behavioral | Strategy | Allows switching between different algorithms at runtime (e.g., choosing between espresso, cappuccino, or filter coffee brewing strategies). |