Introduction to OOP using Java

Saugata BoseIntroduction to OOP using Java

Different Programming Paradigms

Structured Programming

Object Oriented Programming

Java is an Object Oriented Language

ObjectsClassInheritanceEncapsulation

Example of a Java Codeclass Hello {public static void main(String[] args) {System.out.println(Hello World !!!); }}Hello.javaC:\javac Hello.java

C:\java HelloClass NameHello.class

OS/Hardwaremachine code

C source codehello.cgcchello.exe

Platform Dependent JVM

Java source codehello.javajavachello.class

OS/HardwarePlatform Independent

Objects Everywhere

NameHeightWeightEye ColormrBeanmyLamp

ColorHeight

IdentityProperties

Objects have state

Objects have behavior

Then what are objects .

How to interact with program?Service Provider

A class represents a concept, and an object represents the embodiment of a class

Objects and Classes

Bank AccountJohns Bank AccountBalance: $5,257Bills Bank AccountBalance: $1,245,069datamethods

Java Software

Person

Sakib

TamimTamimSakib: Say your nameclass Person{String askName(Person obj){System.out.println("My name is "+obj.toString());}}

class Main{public static void main(String[] args){Person shakib=new Person();Person tamim=new Person();shakib.askName(tamim);}}

Inheritance

Class Hierarchy

Generalization and Specialization

Encapsulation

Separation Why Java then?ModularityInformation Hiding class A{ int noOneCanSeeMe=5; int display(){System.out.println("Anyone can see me");}}Access Modifierspublicprivatepublic