1 The JAVA Language Object Oriented Technology Mithani Binjan M

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The

JAVA Language

Object Oriented

Technology

Mithani Binjan M

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Programming Languages

•To adapt to changing environments and uses•To implement

refinements and improvements

in the art of programming

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History of OOPs In 1960s Birth of Structured

Programming Language

In early 1980s object-oriented

programming (OOP)

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History of OOPs In 1979 C++ invented by

Bjarne Stroustrup 1980s and the early 1990s,

C++ took hold.

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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)

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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

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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.

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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

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JVM Interpreter JVM needs to be implemented for each

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

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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.

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Java Buzzwords SimpleSecurePortableObject-orientedRobust

MultithreadedArchitecture-neutralInterpretedHigh performanceDistributedDynamic

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Java Versions Java 1.0Java 1.1Java 2Java 2, version 1.2Java 2, version 1.3

Java 2, version 1.4Java 2, version 1.5 Java 2, version 1.6

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Java the OOP Language The Three OOP Principles

• Encapsulation

• Inheritance

• Polymorphism

Abstraction

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Encapsulation

getB( )

A B

getA()

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InheritanceBird

Flying Non-Flying

Robin Swallow Penguin Kiwi

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PolymorphismShape

Draw( )

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

Rectangle Circle Triangle

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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

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Class• Set of Data & Code is class

•User defined data-type

• Example: Fruit, Furniture Vehicle

CLASS

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

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

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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

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Data Types• Java supports eight different basic data types.

TypeSize in bytes

Description Keyword

Character 2 16-bit Unicode

char

Boolean - true / false 1-bit boolean

Byte 1 8-bit byteShort 2 16-bit shortInteger 4 32-bit int

Long 8 64-bit longFloat 4 32-bit floatDouble 8 64-bit double

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Declaration & Initialization of variable

Datatype varName; // Declaration of Variable

varName = Value;

Example:

int count = 22;

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Declaration & Initialization of variable

float x, y, z;

// value here considers as ‘double’ type

x = 10.35;

x = 10.35f;

y = 24.56F;

z = y;

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Declaration & Initialization of variable

long m = 254836L; 

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

Output:

The value of m is 254936

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Declaration & Initialization of variable

Character & Strings

 char ch = ‘A’;

 String s1= “This is Testing”;

//String is a class provide by Java.

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Guess the OutputClass 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);

}

}