OOPs

🧊 Abstraction Abstraction is the process of hiding implementation details and exposing only the essential features. It allows developers to focus on what an object does instead of how it does it. 🧱 In Java, Abstraction Is Achieved By: Abstract classes (abstract keyword) Interfaces (fully abstract) 🧪 Example Using Abstract Class abstract class Animal { abstract void makeSound(); void breathe() { System.out.println("Breathing..."); } } class Dog extends Animal { void makeSound() { System.out.println("Bark"); } } 🧪 Example Using Interface interface Drawable { void draw(); } class Circle implements Drawable { public void draw() { System.out.println("Drawing Circle"); } } ✅ Benefits of Abstraction Reduces complexity Increases reusability Enforces standardization (especially through interfaces) Helps in designing scalable and modular systems 🔗 Related Notes History and Evolution OOPs Principles Features of Java Encapsulation Inheritance Polymorphism

🔁 Polymorphism Polymorphism allows one interface to be used for different underlying forms (data types). It enables the same method name to behave differently depending on the context — improving flexibility and maintainability. 🎯 Types of Polymorphism in Java Compile-time (Static) Polymorphism Achieved via method overloading — same method name with different parameters. Runtime (Dynamic) Polymorphism Achieved via method overriding — subclass provides a specific implementation of a method defined in its superclass. ...

🔐 Encapsulation Encapsulation is one of the four core principles of Object-Oriented Programming. It involves wrapping data and code that operates on the data into a single unit: the class. 🧩 Key Concepts Declaring variables as private to prevent direct access from outside. Providing public methods (getters/setters) to read or modify private variables. Helps enforce data protection, validation, and clean APIs. 📌 Why Use Encapsulation? Keeps internal implementation hidden Prevents external interference or misuse Allows safe and controlled access Promotes modularity and maintainability 🧪 Java Example class Student { private int age; // Setter with validation public void setAge(int a) { if (a > 0) age = a; } // Getter public int getAge() { return age; } } 🔗 Related Notes History and Evolution OOPs Principles Features of Java Inheritance Polymorphism Abstraction

🕰️ Object Oriented Programming – History and Evolution Object-Oriented Programming (OOP) emerged to tackle the increasing complexity of software systems. It provides a structured way to organize code around objects, which combine data and behavior. 📅 Timeline of OOP Evolution 1960s – Simula (Norway) Introduced classes and objects — the foundation of OOP. 1970s – Smalltalk Fully object-oriented; introduced message passing. 1980s – C++ Extended C with classes, encapsulation, and inheritance. ...