- [What is Object Oriented](#what-is-object-oriented)

- [What is the difference between JDK & JVM?](#what-is-the-difference-between-jdk--jvm)

- [Battle of JDKs. OpenJDK vs Oracle JDK](#battle-of-jdks-openjdk-vs-oracle-jdk)

- [Details](#details)

- [Character constant vs String Constant](#character-constant-vs-string-constant)](#character-constant-vs-string-constantcharacter-constant-vs-string-constant)

- [Boxing & Unboxing](#boxing--unboxing)

- [StingBuilder vs StringBuffer and immutability](#stingbuilder-vs-stringbuffer-and-immutability)

- [Language features](#language-features)

- [Constructors](#constructors)

- [Can the constructor be overridden?](#can-the-constructor-be-overridden)

- [Difference between overloading and overriding?](#difference-between-overloading-and-overriding)

- [Deconstructing the main](#deconstructing-the-main)](#deconstructing-the-maindeconstructing-the-main)

- [Accessing non-static member from static method](#accessing-non-static-member-from-static-method)

- [Difference between interface & abstract class](#difference-between-interface--abstract-class)

- [Difference between instance variables & local variables](#difference-between-instance-variables--local-variables)

- [Object creation](#object-creation)

- [Static vs instance methods](#static-vs-instance-methods)

- [equals](#equals)

- [hashCode](#hashcode)

- [equals + hashCode](#equals--hashcode)

- [final](#final)

- [Exception handling](#exception-handling)

- [System object](#system-object)

- [Deep copy vs Shallow copy](#deep-copy-vs-shallow-copy)

- [References](#references)

- [Access Modifiers](#access-modifiers)

- [Serialization](#serialization)

- [I/O](#io)

- [Stream vs Reader](#stream-vs-reader)

Object-oriented is a programming paradigm that relates the programming to logical objects. Like real life objects, programming objects will have their characteristics(state) & functionalities(methods). Some other features like inheritance, abstraction (), polymorphism, encapsulation (hiding the data implementation) will be applied to programming too.

A car is a type of vehicle which has a brand, registration no, mileage etc and it can be driven, gears can be shifted.

class Car extends Vehicle{

protected String brand;

protected String regNo;

protected Double mileage;

public void drive(){

// Drive the car

}

public void shiftGear(int gear){

// Shift gear

}

}