Sankalp Singh Mehra’s Post

Day 5 -> More Creational Design Patterns 🚀 Today I explored three important design patterns: 🔹 Singleton → Ensures only one instance of a class exists 🔹 Builder → Helps construct complex objects step by step 🔹 Prototype → Creates new objects by cloning existing ones 💡 Key realization: 👉 Object creation is not just about new keyword 👉 It’s about control, flexibility, and scalability Understanding these patterns is helping me think beyond coding → towards better system design. ⭐Now I can see where each pattern actually fits in real systems #Day5 #LLD #DesignPatterns #SystemDesign #Java #SoftwareEngineering

Exploring the State Design Pattern Lately, I’ve been diving deeper into design patterns, and today I explored the State Design Pattern — a simple yet powerful way to manage complex object behavior. What problem does it solve? When an object’s behavior changes based on its internal state, we often end up with multiple if-else or switch conditions. This quickly becomes messy and hard to maintain. State Pattern to the rescue! It allows an object to alter its behavior when its internal state changes — almost as if the object changes its class. Key Idea: Encapsulate each state as a separate class and delegate behavior to the current state object. Benefits: 1. Cleaner code (no more conditional clutter) 2. Easier to extend (add new states without modifying existing logic) 3. Better adherence to Open/Closed Principle Real-world example: Think of a media player: Playing Paused Stopped Each state behaves differently for the same action (like pressing the play button). As a backend engineer, I find this pattern especially useful when dealing with workflows, order processing systems, or lifecycle-based entities. Next step: implementing it in a real-world project to see its impact firsthand. #DesignPatterns #Java #BackendDevelopment #SystemDesign #CleanCode #LearningJourney

Day 4 - Creational Design Patterns 🚀 Today I explored some of the most important Creational Design Patterns: 🔹 Simple Factory → Centralized object creation 🔹 Factory Method → Subclasses decide which object to create 🔹 Abstract Factory → Create families of related objects 💡 Key realization: 👉 Object creation logic should not be tightly coupled with business logic 👉 These patterns make systems flexible, scalable, and extensible From writing objects → to designing object creation #Day4 #LLD #DesignPatterns #SystemDesign #Java #SoftwareEngineering

🚀 Mastering the Proxy Design Pattern in LLD Have you ever wondered… 👉 Why directly access a heavy object when you can use a smart middle layer? That’s exactly where the Proxy Design Pattern comes in! 💡 🔍 What is it? Proxy Pattern is a structural design pattern where a proxy object controls access to a real object, adding extra functionality like security, caching, or lazy loading. 🧠 Key Components: • Subject → Common interface • RealSubject → Actual object (heavy work) • Proxy → Controls access & adds logic • Client → Uses proxy instead of real object 📊 Diagram Explanation: Client → Proxy → Real Object 👉 Step-by-step: Client sends request to Proxy Proxy checks (cache / security / lazy load) If needed → creates Real Object Proxy forwards request Result returned to Client 💡 Proxy acts like a smart gatekeeper ⚙️ Why use Proxy? ✅ Lazy Loading (load only when needed) ✅ Security & Access Control ✅ Caching for performance ✅ Logging & Monitoring 🎯 Simple Example (Easy to Understand): Imagine loading an image 📸 from disk (heavy operation) Instead of loading it directly every time: 👉 We use a Proxy • First call → Image loads from disk • Next calls → Already loaded (no delay) 💻 Code idea: Image img = new ProxyImage("photo.jpg"); img.display(); // loads + displays img.display(); // only displays (cached) 🔥 Real-Life Example: Think of a credit card 💳 – it acts as a proxy for your bank account. You don’t carry cash, but still access money when needed! 💡 Quick Tip: 👉 Proxy = Control + Delay + Extra Logic 🎯 This pattern is super useful in: • Image loading (lazy loading) • API calls (caching) • Authentication systems • Distributed systems If you're preparing for LLD interviews or building scalable systems, this is a MUST-KNOW pattern 💯 💬 Drop a comment if you want more design pattern breakdowns! #ProxyPattern #SystemDesign #LLD #SoftwareEngineering #Coding #DesignPatterns #Developers #Java #Programming #Tech

🚦 Designing a Traffic Light System — Using State Design Pattern Ever noticed how a traffic light smoothly changes from Red → Green → Yellow without confusion............... It looks simple, but behind the scenes, each color represents a different behavior. I recently built a mini version of this system in Java, and it turned into a great example of using the State Design Pattern effectively. 🧩 The Problem We have a traffic light with multiple states: 🔴 Red → Stop 🟢 Green → Go 🟡 Yellow → Slow down Now the challenge: 👉 The system should behave differently based on its current state 👉 And it should be easy to add new states like: Blinking (night mode) Maintenance mode ❌ The Naive Approach Most people start with: if (color.equals("RED")) { ... } else if (color.equals("GREEN")) { ... } else if (color.equals("YELLOW")) { ... } 🚫 Problems: Not scalable Becomes messy with more states Violates Open/Closed Principle Hard to maintain ✅ The Better Approach: State Design Pattern We shift from conditions → objects Instead of one class handling everything: 👉 Each state becomes its own class ⚙️ How It Works Step 1: Define a State Interface Each state defines what happens next Step 2: Create Separate State Classes RedState → decides next = Green GreenState → decides next = Yellow YellowState → decides next = Red Each state controls its own behavior 🔥 Step 3: Context Class (TrafficLight) 👉 Holds the current state 👉 Delegates behavior to that state 👉 The context doesn’t care how things work internally 🔥 Why This Design Wins ✅ Open/Closed Principle Add new modes without modifying old code ✅ High Cohesion Each class = one responsibility ✅ Low Coupling States don’t interfere with each other ✅ Cleaner Thinking You model real-world behavior naturally 🌍 Real-World Use Cases 🎬 Media players (Play, Pause, Stop) 🥤 Vending machines (NoCoin, HasCoin) 📄 Document workflows (Draft, Review, Published) 🎮 Game characters (Idle, Running, Attacking) 🚀 Interview Insight If you explain this well, you show: 1. Real understanding of design patterns 2. Ability to write scalable code 3. Strong problem-solving mindset #SystemDesign #Java #DesignPatterns #StatePattern #CleanCode #SoftwareEngineering #InterviewPrep

"Good code solves a problem. Great code is designed to survive change." Design Patterns have become one of my primary area of new learning. I've started at the very beginning of design patterns and am slowly working my way up to the advanced concepts. At first I didn't have really good coding practices; my code was really in a mess; classes were tightly coupled, each of my objects were created at different places, when I made any small change it caused multiple files to break. Until; I found out that there are three groups of design pattern: (1) Creational Patterns - define how to create an object (examples are Factory, Singleton or Builder) (2) Structural Patterns - define how classes and objects are organized (examples are Adapter, Decorator or Facade) (3) Behavioral Patterns - define how objects interact with each other (examples are Observer, Strategy or Command). After I learned about these groups of design patterns, it has been easier to build my systems. Instead of writing code randomly I now think; Which pattern would be the most appropriate for the specific design challenge I have? Takeaway: Design Patterns are not just a means to prepare for an interview, they can also be viewed as way of thinking, providing a standard framework for developing scalable solutions. What are some of the design patterns that you work or use in real-world systems? #Java #ProblemSolving #CodingJourney #DeveloperCommunity #DesignPatterns #SoftwareArchitecture

Most developers learn syntax. Great engineers master design. The Gang of Four (GoF) patterns are timeless principles that turn code into scalable architecture. Creational patterns manage object creation. Structural patterns shape system design. Behavioral patterns define communication. From Singleton to Strategy, these patterns solve recurring problems with proven solutions. Frameworks like Spring already use them— the question is: do you recognize them? Don’t just write code. Design systems that last. 👉 Save this for your next design review #SystemDesign #Java #SoftwareArchitecture #DesignPatterns #TechLeadership

Most developers write this kind of code at some point: if (obj instanceof File) else if (obj instanceof Folder) It works. But it doesn’t scale. As your system grows, this approach leads to: Increasing conditional logic Tight coupling Code that is hard to extend and maintain This is where the Composite Design Pattern becomes powerful. Instead of asking: "What type of object is this?" You design your system so that every object responds to the same behavior. Now you simply write: root.show(); No type checking. No conditional branching. Just clean, extensible code. The key idea: Treat individual objects and groups of objects uniformly. This pattern is widely used in: File systems UI component trees (Angular, React) Organization hierarchies Menu structures Why it matters in real projects: Reduces complexity Improves readability Makes systems easier to extend without modifying existing code Good design is not about making code work. It is about making code evolve. If you are preparing for interviews or working on scalable systems, this is a pattern worth mastering. #Java #SystemDesign #DesignPatterns #CleanCode #SoftwareEngineering #BackendDevelopment #InterviewPreparation

🔄 Continuing my Design Patterns journey… After exploring Creational and Structural patterns, today I focused on Behavioral Design Patterns — which define how objects communicate and interact with each other. 💡 Why Behavioral Patterns? They help manage complex communication between objects, making systems more flexible, maintainable, and easier to extend. 📌 Types of Behavioral Design Patterns (GoF – 11 patterns): 1️⃣ Strategy – Defines a family of algorithms and makes them interchangeable 2️⃣ Observer – Notifies multiple objects when one object changes 3️⃣ Command – Encapsulates a request as an object 4️⃣ Chain of Responsibility – Passes requests along a chain of handlers 5️⃣ State – Changes behavior when internal state changes 6️⃣ Template Method – Defines a skeleton of an algorithm with customizable steps 7️⃣ Mediator – Centralizes communication between objects 8️⃣ Iterator – Provides a way to access elements sequentially 9️⃣ Memento – Saves and restores object state 🔟 Visitor – Adds new operations without modifying existing classes 1️⃣1️⃣ Interpreter – Defines grammar and interprets expressions 🧠 Key takeaway: Behavioral patterns focus on how objects interact, helping reduce tight coupling and improving flexibility in code. 🚀 Tomorrow, I’ll implement these patterns with simple code examples. #DesignPatterns #BehavioralPatterns #ObjectOrientedDesign #Java #ProgrammingConcepts #SoftwareEngineering #CodingJourney

🔄 Continuing my Design patterns learning journey… After understanding Creational Design Patterns, today I explored Structural Design Patterns — which focus on how different components of a system are structured and connected. 💡 Why Structural Patterns? They simplify complex systems by organizing relationships between classes and objects, making them easier to scale, extend, and maintain. 📌 Key Structural Design Patterns: 1️⃣ Adapter – Helps incompatible interfaces work together 2️⃣ Bridge – Separates abstraction from implementation for flexibility 3️⃣ Composite – Treats individual objects and groups uniformly 4️⃣ Decorator – Adds new behavior dynamically without changing existing code 5️⃣ Facade – Provides a simple interface to a complex system 6️⃣ Flyweight – Optimizes memory usage by sharing common data 7️⃣ Proxy – Controls access to an object (e.g., security, caching, lazy loading) 🧠 These patterns are especially useful when building scalable systems where components need to interact efficiently without tight coupling. 🚀 Tomorrow, I’ll dive into code implementations. #DesignPatterns #Java #BackendDevelopment