OOP->A Bird's-eye view
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This document introduces object-oriented programming concepts like classes, objects, inheritance, and encapsulation using Java as an example. It provides a simple "Hello World" Java program to demonstrate a Java class and explains how Java code is compiled to bytecode that can run on any platform with a Java Virtual Machine. Key concepts like objects having state through attributes and behavior through methods are defined. The document also shows an example of classes defining objects like bank accounts and persons to demonstrate how classes represent concepts and objects are instances of classes.
![Example of a Java Code
class Hello {
public static void main(String[] args) {
System.out.println(“Hello World !!!”);
}
}
Hello.java
C:javac Hello.java
C:java Hello
Class
Name
Hello.
class](https://image.slidesharecdn.com/saugata-161006103941/85/OOP-A-Bird-s-eye-view-3-320.jpg)
![Java Software
Person
Sakib Tamim
“Tamim”Sakib: Say your
name
class 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(ta
mim);
}
}](https://image.slidesharecdn.com/saugata-161006103941/85/OOP-A-Bird-s-eye-view-10-320.jpg)
OOP->A Bird's-eye view
- 1. Saugata Bose Introduction to OOP using Java
- 2. Different Programming Paradigms Structured Programming Object Oriented Programming Java is an Object Oriented Language Objects Class Inheritance Encapsulation
- 3. Example of a Java Code class Hello { public static void main(String[] args) { System.out.println(“Hello World !!!”); } } Hello.java C:javac Hello.java C:java Hello Class Name Hello. class
- 4. OS/Hardware machine code C source code hello.c gcc hello.exe Platform Dependent JVM Java source code hello.java javac hello.class OS/Hardware Platform Independent
- 6. Objects have state… …
- 8. 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
- 9. Objects and Classes Bank Account John’s Bank Account Balance: $5,257 Bill’s Bank Account Balance: $1,245,069 data methods
- 10. Java Software Person Sakib Tamim “Tamim”Sakib: Say your name class 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(ta mim); } }
- 11. Inheritance Class Hierarchy Generalization and Specialization
- 12. Encapsulation Separation Why Java then? Modularity Information Hiding class A{ int noOneCanSeeMe=5; int display(){ System.out.println("Any one can see me"); } } Access Modifiers public private public