Java Intermediate Course — OOP (Object-Oriented Programming)

This repository contains Java programs demonstrating Object-Oriented Programming (OOP) concepts, with a focus on inner classes and basic inheritance examples.

---

🧱 What is OOP?

Object-Oriented Programming helps you build programs using real-world concepts like Car, Student, BankAccount, etc.
Key OOP concepts included in this repository:

1. Class & Object

   • A class is a blueprint.
   • An object is a real instance created from that blueprint.

2. Constructors

   • Constructors initialize object values automatically when an object is created.

3. The this Keyword

   • Refers to the current object.

4. Inheritance

   • Allows one class to use properties and methods of another class.

5. Polymorphism

   • Many forms — the same method name behaves differently depending on context.

6. Encapsulation

   • Keeps data safe using private variables with getters and setters.

7. Abstraction

   • Hides complex implementation details and shows only the essentials.

8. Static Keyword

   • Belongs to the class, not to any object.

9. Final Keyword

   • Prevents changes to variables, methods, or classes.

10. Inner Classes

    • Classes defined inside other classes.
    • Useful for logically grouping classes that are only used in one place.

---

🧠 Advanced Java Concepts

1. Exception Handling

   • Allows programs to handle runtime errors gracefully using try, catch, and finally.

2. File Handling

   • Enables reading from and writing to files for data storage and retrieval.

3. Collections Framework

   • Provides dynamic data structures like ArrayList, HashMap, and HashSet for managing data.

4. Multithreading

   • Lets multiple parts of a program run concurrently to improve performance.

5. Lambda Expressions

   • Offers a shorter way to define methods or functions inline for cleaner code.

6. Streams API

   • Simplifies processing of collections using functional operations like filter, map, and collect.

7. Generics

   • Allows writing reusable and type-safe code that works with any data type.

8. Serialization

   • Converts objects into a byte stream to save or transfer them, and restores them later.