Chapter 1: OOPs Concepts

Object-Oriented Programming (OOP) is the cornerstone of Java enterprise architecture. Modeling real-world entities through encapsulated state, polymorphic behaviors, structured hierarchies, and clean abstractions enables maintainable, high-scale backend systems.

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🧭 Subtopics & Curriculum

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Foundations & Memory1.1

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1.1 Classes, Objects & Instantiation

• 1. Class vs Object: The Conceptual Difference
• 2. JVM Memory Allocation During Object Creation
• 3. Anatomy of a Clean Java Class

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Data Protection1.2

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1.2 Encapsulation & Access Modifiers

• 1. Why Encapsulation Matters
• 2. Java Access Modifiers Matrix
• 3. Defensive Copying: Preventing Leakage

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Hierarchies1.3

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1.3 Inheritance & Composition

• 1. Inheritance (IS-A Relationship)
  • Key Inheritance Constraints in Java
• 2. Composition (HAS-A Relationship)
• 3. "Favor Composition over Inheritance"

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Dynamic Dispatch1.4

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1.4 Polymorphism & Method Dispatch

• 1. Compile-Time Polymorphism (Method Overloading)
• 2. Runtime Polymorphism (Dynamic Method Dispatch)
• 3. How Dynamic Dispatch Works Under the Hood
• 4. Covariant Return Types

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Contract Architecture1.5

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1.5 Abstraction & Modern Interfaces

• 1. Abstract Classes vs Interfaces (Java 8 to Java 21)
• 2. Evolution of Java Interfaces
  • A. Default Methods (Java 8)
  • B. Static Methods (Java 8)
  • C. Private Methods (Java 9)
• 3. Resolving Multiple Interface Collisions

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Architecture Quality1.6

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1.6 SOLID Design Principles

• 1. Single Responsibility Principle (SRP)
• 2. Open / Closed Principle (OCP)
• 3. Liskov Substitution Principle (LSP)
• 4. Interface Segregation Principle (ISP)
• 5. Dependency Inversion Principle (DIP)

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