1

The

JAVA Language

Object Oriented

Technology

Jainul A. Musani

2

Programming Languages

•To adapt to changing environments and uses•To implement

refinements and improvements

in the art of programming

Jainul A. Musani

3

History of OOPs In 1960s Birth of Structured

Programming Language

In early 1980s object-oriented

programming (OOP)

Jainul A. Musani

4

History of OOPs In 1979 C++ invented by

Bjarne Stroustrup 1980s and the early 1990s,

C++ took hold.

Jainul A. Musani

5

History of OOPs In 1991 Java was conceived

By James Gosling, Patrick Naughton, Chris Warth, Ed Frank, and Mike Sheridan

At Sun Microsystems, Inc.

“Oak” “Java” (1995) Jainul A. Musani

6

Java the Language of Internet

Expanded the universe of objects Objects can move about freely

in cyberspace. On a network :

passive information/data dynamic, active programs

Jainul A. Musani

7

Java Applications -&- Java Applets

An application is a program that runs on your computer, under the operating system of that computer. An applet is an application designed to be transmitted over the Internet and executed by a Java-compatible Web browser.

Jainul A. Musani

8

Java’s Magic: The Bytecode

An application a highly optimized set of instructions designed to be executed by the Java run-time system - JVM JVM - Java Virtual Machine Truly Portable

Jainul A. Musani

9

JVM Interpreter JVM needs to be implemented for each

platform. Platform independent Bytecode enables the Java run-time system to execute programs much faster

Jainul A. Musani

10

Just In Time (JIT) compiler

Sun supplies its Just In Time (JIT) compiler for bytecode. (Java-2) JIT compiler is part of the JVM. It compiles bytecode into executable code in real time, on a piece-by-piece, demand basis.

Jainul A. Musani

11

Java Buzzwords Simple Secure Portable Object-oriented Robust Multithreaded

Jainul A. Musani

Architecture Neutral Interpreted High performance Distributed Dynamic

12

Java Versions Java 1.0 Java 1.1 Java 2 Java 2, ver.1.2 Java 2, ver.1.3

Jainul A. Musani

Java 2, ver.1.4 Java 2, ver.1.5 Java 2, ver.1.6

13

Java the OOP Language The Three OOP Principles

• Encapsulation

• Inheritance

• Polymorphism

Abstraction

Jainul A. Musani

14

Encapsulation

Jainul A. Musani

getB( )

A B

getA( )

15

Inheritance

Jainul A. Musani

Bird

Flying Non-Flying

Robin Swallow Penguin Kiwi

16

Polymorphism

Jainul A. Musani

ShapeDraw( )

Draw( a, b ) Draw( a ) Draw( a, b, c )

Rectangle Circle Triangle

17

Object• Run time entity

• Represent a

Person, Book,

Bank Account, etc…

• User defined data

• Example:

Object : StudentDATA: Roll_no Name Percentage

FUNCTIONS: Total Average Display

Jainul A. Musani

18

Class• Set of Data & Code is class

•User defined data-type

• Example: Fruit, Furniture Vehicle

CLASS

DATA: ::::::::::::: :::::::::::::

FUNCTIONS: :::::::::::: ::::::::::::

Jainul A. Musani

19

Variables & Data Types• Named memory location that holds a value

• In java variables must be declared before it use in the program

• Variable must be of some datatype, it tells

compiler what type of value it can store

Jainul A. Musani

20

Data Types• Java supports eight different basic data types.

Jainul A. Musani

Type Size in Bytes

Description Keyword

Character

2 16 bit Unicode

char

Boolean 1 bit 1 – bit booleanByte 1 8 – bits byteShort 2 16 – bits shortInteger 4 32 – bits intLong 8 64 – bits longFloat 4 32 – bits floatDouble 8 64 – bits double

21

Declaration & Initialization of variable

Jainul A. Musani

Datatype varName; // Declaration of Variable

varName = Value;

Example:

int count = 22;

22

Declaration & Initialization of variable

Jainul A. Musani

float x, y, z;

// value here considers as ‘double’ type

x = 10.35;

x = 10.35f;

y = 24.56F;

z = y;

23

Declaration & Initialization of variable

Jainul A. Musani

long m = 254836L; 

System.out.println(“The value of m is “ + m);

Output:

The value of m is 254936

24

Declaration & Initialization of variable

Jainul A. Musani

Character & Strings

 char ch = ‘A’;

 String s1= “This is Testing”;

//String is a class provide by Java.

25

Guess the Output

Jainul A. Musani

Class test

{

public static void main(String s[])

{

char c;

boolean flg;

int a;

System.out.println(c);

System.out.println(flg);

System.out.println(a);

}

}