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← Abstract Factory Design Pattern Design Patterns Home Builder Design Pattern → Reading Time: 15–20 minutes The Prototype Design Pattern is a creational design pattern that allows object creation by copying an existing object instead of creating a new instance from scratch. This pattern improves performance when object creation is expensive, complex, or resource-intensive. Instead of repeatedly constructing objects, the system clones an existing object and modifies it as needed. This guide explains Prototype Design Pattern from beginner to advanced level with simple explanations, real-world examples, cloning techniques, shallow vs deep copy concepts, performance benefits, and best practices. Contents [ hide ] What is Prototype Design Pattern The Prototype pattern creates new objects by copying an existing object (prototype) instead of creating new objects using constructors. In simple words, Prototype solves one main problem: Create objects efficient...

← Proxy Design Pattern Design Patterns Home Reading Time: 14–17 minutes Dependency Injection (DI) is a design principle and design pattern used to achieve loose coupling between classes. Instead of a class creating its own dependencies, the required dependencies are provided from outside. Dependency Injection is widely used in modern Java applications, especially in frameworks like Spring Boot. It improves testability, flexibility, and maintainability of code. This tutorial explains Dependency Injection from beginner to advanced level with simple examples, step-by-step implementation, and real-world understanding. Contents [ hide ] What is Dependency Injection Dependency Injection is a technique where an object receives its dependencies from an external source instead of creating them internally. Simple definition: Do not create dependencies inside a class. Inject them from outside. Understanding Dependency and Injection What is Dependency A depend...

← Template Method Design Pattern Design Patterns Home Dependency Injection → Reading Time: 12–15 minutes The Proxy Design Pattern is a structural design pattern that provides a placeholder or substitute object to control access to another object. Instead of interacting directly with the original object, the client communicates through a proxy. The proxy controls operations such as access control, caching, logging, lazy initialization, or performance optimization. This tutorial explains the Proxy pattern from beginner to advanced level with simple examples, step-by-step implementation, and real-world understanding. Contents [ hide ] What is Proxy Design Pattern The Proxy pattern provides a surrogate object that controls access to a real object. Simple definition: Proxy acts as a middle layer between client and actual object. The client communicates with proxy instead of directly interacting with the real object. Why Do We Need Proxy Pattern Somet...

← Observer Design Pattern Design Patterns Home Proxy Design Pattern → Reading Time: 11–14 minutes The Template Method Design Pattern is a behavioral design pattern that defines the skeleton of an algorithm in a base class and allows subclasses to override specific steps without changing the overall structure. This pattern is useful when multiple classes follow the same process but differ in certain steps. It promotes code reuse, consistency, and follows the Open Closed Principle. This tutorial explains the Template Method pattern from beginner to advanced level with simple examples, step-by-step implementation, and real-world understanding. Contents [ hide ] What is Template Method Design Pattern The Template Method pattern defines the overall structure of an algorithm in a base class method and allows subclasses to implement or override certain steps. Simple definition: Template Method defines “how a process works” while subclasses define “how specif...

← Adapter Design Pattern Design Patterns Home Template Method Design Pattern → Reading Time: 14–16 minutes The Observer Design Pattern is a behavioral design pattern that defines a one-to-many dependency between objects. When one object changes its state, all its dependent objects are automatically notified and updated. This pattern is widely used in event-driven systems, messaging systems, UI frameworks, and notification services. This tutorial explains the Observer pattern from beginner to advanced level with simple explanations, real-world examples, step-by-step implementation, and interview-level concepts. Contents [ hide ] What is Observer Design Pattern The Observer pattern establishes a relationship where one object (called Subject) maintains a list of dependents (called Observers) and automatically notifies them when its state changes. Simple definition: When one object changes, all subscribed objects get notified automatically. Why Do We Ne...

← Strategy Design Pattern Design Patterns Home Observer Design Pattern → Reading Time: 10–13 minutes The Adapter Design Pattern is a structural design pattern that allows two incompatible classes to work together. It acts as a bridge between two different interfaces by converting one interface into another that the client expects. This pattern is useful when you want to reuse existing code but its interface does not match the required interface of your application. This tutorial explains Adapter pattern from beginner to advanced level with simple examples, real-world understanding, implementation steps, and interview-level concepts. Contents [ hide ] What is Adapter Design Pattern The Adapter pattern converts the interface of a class into another interface that the client expects. Simple definition: Adapter acts as a connector between two incompatible systems. It allows existing classes to work together without modifying their source code. Why Do ...

← Builder Design Pattern Design Patterns Home Adapter Design Pattern → Reading Time: 12–15 minutes The Strategy Design Pattern is a behavioral design pattern that allows you to define multiple ways of performing a task and choose one at runtime. Instead of hardcoding logic using large if-else or switch conditions, each behavior is placed inside a separate class. This makes the application flexible, easy to extend, and simple to maintain. Strategy pattern is commonly used when an application needs different variations of the same functionality. This guide explains Strategy pattern from beginner to advanced level with simple explanations, step-by-step implementation, and real-world examples. Contents [ hide ] What is Strategy Design Pattern The Strategy pattern defines a family of algorithms, encapsulates each algorithm into separate classes, and allows switching between them at runtime. Simple definition: Strategy pattern allows changing behavior dynam...

← Prototype Design Pattern Design Patterns Home Strategy Design Pattern → Reading Time: 11–14 minutes The Builder Design Pattern is a creational design pattern used to construct complex objects step by step. It separates the construction of an object from its representation, allowing the same construction process to create different representations. The Builder pattern is very useful when a class has many parameters, especially optional parameters. It improves readability, flexibility, and maintainability of the code. Contents [ hide ] Why Do We Need Builder Pattern Let us understand the problem first. Problem with Multiple Constructor Parameters Suppose we have a User class with many attributes: package com.codekatha; class User { private String name; private int age; private String email; private String phone; private String address; public User(String name, int age, String email, String phone, String address) { t...

← Factory Design Pattern Design Patterns Home Prototype Design Pattern → Reading Time: 20 minutes The Abstract Factory Design Pattern is a creational design pattern that provides an interface to create families of related objects without specifying their concrete classes. It is an extension of the Factory Pattern. While a Factory creates one type of object, an Abstract Factory creates a group of related objects that work together. This pattern is widely used in large enterprise systems where multiple related components must be created consistently. This tutorial explains the Abstract Factory pattern in a beginner-friendly way with simple examples, step-by-step implementation, real-world understanding, and interview-level concepts. Contents [ hide ] What is Abstract Factory Pattern The Abstract Factory pattern provides a way to create families of related objects without directly creating their concrete classes. Simple definition: Abstract Factory c...

← Singleton Design Pattern Design Patterns Home Abstract Factory Design Pattern → Reading Time: 10–12 minutes The Factory Design Pattern is one of the most commonly used creational design patterns in Java. It provides a way to create objects without exposing the object creation logic to the client. Instead of creating objects using the new keyword directly, object creation is delegated to a factory class. This pattern improves code flexibility, reduces tight coupling, and makes applications easier to maintain and extend. This tutorial explains the Factory pattern in a beginner-friendly way with simple examples, real-world understanding, implementation steps, and interview-level concepts. Contents [ hide ] What is Factory Design Pattern The Factory pattern provides an interface or method to create objects while hiding the actual creation logic. Instead of creating objects directly using the new keyword, we ask a factory to create the object. Simple de...

← SOLID Principles Design Patterns Home Factory Design Pattern → Reading Time: 15–20 minutes The Singleton Design Pattern is one of the most popular creational design patterns in Java. It ensures that only one instance of a class exists throughout the application and provides a global access point to that instance. This pattern is widely used in enterprise applications for managing shared resources such as configuration objects, logging services, caching, thread pools, and database connections. This guide explains Singleton from beginner to advanced level with simple explanations, real-world examples, thread safety concepts, performance optimization, and ways Singleton can be broken. Contents [ hide ] What is Singleton Design Pattern The Singleton pattern ensures that a class has only one object and provides a global method to access that object. In simple words, Singleton solves two problems: Ensure only one object is created. Provide global access...

Design Patterns Home Singleton Design Pattern → Reading Time: 13-15 minutes Contents [ hide ] SOLID is a set of five design principles that help developers write clean, maintainable, scalable, and loosely coupled software. These principles are widely used in object-oriented programming and are very important for Java developers, especially when building enterprise applications using frameworks like Spring. SOLID helps solve common software problems like tightly coupled code, difficult maintenance, poor scalability, and hard-to-test systems. SOLID stands for: S — Single Responsibility Principle O — Open Closed Principle L — Liskov Substitution Principle I — Interface Segregation Principle D — Dependency Inversion Principle This tutorial explains each principle with simple examples so that even beginners can understand easily. Single Responsibility Principle (SRP) Definition: A class should have only one reason to change, meaning a class should have...