Core Java Part-1

1

The

JAVA Language

Object Oriented

Technology

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2

Programming Languages

•To adapt to changing environments and uses•To implement

refinements and improvements

in the art of programming

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3

History of OOPs In 1960s Birth of Structured

Programming Language

In early 1980s object-oriented

programming (OOP)

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4

History of OOPs In 1979 C++ invented by

Bjarne Stroustrup 1980s and the early 1990s,

C++ took hold.

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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

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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.

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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

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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

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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.

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11

Java Buzzwords Simple Secure Portable Object-oriented Robust Multithreaded

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Architecture Neutral Interpreted High performance Distributed Dynamic

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

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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

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14

Encapsulation

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getB( )

A B

getA( )

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Inheritance

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Bird

Flying Non-Flying

Robin Swallow Penguin Kiwi

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Polymorphism

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ShapeDraw( )

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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18

Class• Set of Data & Code is class

•User defined data-type

• Example: Fruit, Furniture Vehicle

CLASS

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

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

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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

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20

Data Types• Java supports eight different basic data types.

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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

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Declaration & Initialization of variable

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Datatype varName; // Declaration of Variable

varName = Value;

Example:

int count = 22;

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Declaration & Initialization of variable

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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

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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

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Character & Strings

 char ch = ‘A’;

 String s1= “This is Testing”;

//String is a class provide by Java.

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Guess the Output

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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);

}

}