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23October2007

Introd

uctionto

Java

Vers

ion

1.0

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23Octobe

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CourseO

bjec

tive

The

Objectiveo

fJavacou

rse

is:

Tounders

tan

dbas

icp

rogramm

ingco

ncep

tsus

ingJava

syn

tax.

Toapprec

iateOOPco

ncep

tsan

dencouragepro

blem

so

lving

us

ing

OOPtec

hn

iques

.

Tounders

tan

dvarious

Java

APIand

how

touse

them

effectiv

elyinpro

jec

ts.

Tounders

tan

dthenee

dforexcep

tion

han

dlingand

how

to

use

inJavaenv

ironme

nt.

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23Octobe

r2007

Wha

tisJ

ava

?

Java

isboth:

AProgramm

ing

language

APlatform

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23Octobe

r2007

TheJav

aProgrammingLa

nguage

Java

isan

Objec

tOriente

dProgramm

ing

language

.

Java

ssyn

tax

iss

imilarto

C/C++syntax

.

Java

isbothcomp

iledand

interpre

ted

.

The

interm

ediateform

isc

alledJava

byte

co

de

,w

hichis

platform

indepen

den

t.

By

teco

des

are

interpre

tedby

JVMduringrun

time

.

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5

23Octobe

r2007

JavaPl

atform

The

JavaP

latform

has

twocomponen

ts:

The

Java

Virtua

lMach

ine

(JVM)

The

Java

App

lica

tion

Programm

ingIn

terface

(JavaA

PI)

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23Octobe

r2007

The

Java

Platform

The

JavaV

Misbase

forJ

avap

latforman

disporte

don

to

various

hardware-b

ase

da

ndOSbasedp

latforms

.

The

JavaA

PIisa

largeco

llec

tiono

fread

y-m

ade

,freque

ntly

use

dc

lass

libraries

,s

tore

dinpac

kages.

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r2007

The

Java

Env

ironmen

tJava

Program

Jav

aVirtua

lmac

hine

Native

OS/Platform

Java

API

JAVA

PLATFO

RM

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ASimpleJavaProgram

/**Thisisour

firs

tJava

Pro

gram

*/

class

FirstC

lass

{ pu

blics

taticvo

idma

in(Str

ingargs

[])

{

System

.ou

t.prin

tln(

He

lloWorl

d.);

}}

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23Octobe

r2007

CompilingandR

unningin

Eclipse

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23Octobe

r2007

JavaDataTypes

Twomajor

da

tatypes

Prim

itiv

e

Because

javaprogra

mhas

torunon

differen

tarch

itec

ture

an

dO

S,

thes

izeof

the

da

tas

hould

rema

insame.

Otherw

ise

,on

differe

ntmac

hinesth

eou

tpu

tw

illbe

differen

t

Re

ference

Allob

jec

tsareo

ftyp

ere

ference

datatype

.Java

do

esn

t

allow

direc

tly

toacce

ssmemory

.Bu

to

bjec

tsarere

fere

d

bypo

interson

ly.

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r2007

Primitiv

eDataTy

pes

In

tegers

by

te

(8bit)

s

hort

(16bit)

int

(32bit)

long

(64bit)

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23Octobe

r2007

Prim

itive

Da

taTypes

Rea

lNumb

ers

floa

t

(32bit)

dou

ble

(64bit)

Other

Type

s

c

har

(16bit)

boo

lean

(true

/false

)

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r2007

Re

ferenc

eDa

taType

s

Examp

les:

Arrays

Strings

Objects

Interfac

es

Thename

referencemeansapo

inter

inthememory

.All

objec

tsare

referre

dby

the

irmemory

loca

tionon

ly.

Butuser

canno

tdire

ctlyaccessme

mory

loca

tion.

Memorym

anagemen

tista

kencare

byJ

VMitse

lf.

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Varia

bleNames

Varia

blenames

inJavaare

lega

lJavaiden

tifiercompris

edo

fa

serieso

fU

nico

dec

haracters

.

Varia

blenamesmus

tnot

be

Java

keywordora

boo

lean

litera

l

Samevaria

blenames

hou

ldno

tappeartw

icew

ithinascope

.

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r2007

JavaOpe

rators

Ari

thme

tic

Opera

tors

+,

-,*,/,%

Unary

Arith

me

tic

Opera

tors

++

,--

Re

lational

an

dCon

ditiona

lOpera

tors

>,

>=

,

,>

,&

,|,^,

~

Ternary

Opera

tor:

()?():()

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23Octobe

r2007

Con

trolF

low

Dec

isionm

aking

if

-else,

sw

itc

h-c

ase

Loop

for,wh

ile,

do-w

hile

Excep

tion

try-c

atc

h-f

ina

lly,

throw

Misce

llane

ous

Break,

con

tinue

,label:,re

turn

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23Octobe

r2007

Arraysin

Java

Javaarraysareo

bjec

ts.

Arrayconta

ins

like-t

ypedva

lues

.

Arraycancon

tainbo

thpr

imitivean

dre

ference

da

tatype

s.

Whenuse

dw

ithre

ference

da

tatypes

,reference

(memory

loca

tion

)is

on

lys

tore

dinarraysan

dnot

therea

lo

bjects

.

Javasupportsmu

ltidimens

iona

larrays.

Theyareno

thin

gbu

t

arrayo

far

rays

.

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23Octobe

r2007

Arraysin

Java

Array

Dec

lara

tion

intmyIn

tegers

[];

int[]my

Integers;

Arraymem

orya

lloca

tion:

intmyIn

tegers

[]=new

int[10];

Array

Initia

liza

tion:

intmyIn

tegers

[]=

{1,2,3,4,5

};

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Stringsin

Java

Asequenc

eo

fc

harac

ters

isencapsu

latedasa

Stringo

bjec

t.

Javauses

+opera

tor

for

Stringconcatena

tion

.

Someuse

fulString

functionsare:

s

.lengt

h();

s

1.e

qua

ls(s2);

s

1.s

ubString

(in

ts

tartIn

dex

,intup

To);

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r2007

Summa

ry

Inthisse

ssionyoule

arnedabout:

JavaProgrammingLanguage

JavaPlatform

JavaEnvironment

FirstJ

avaProgram

DataTypes

Opera

tors

ControlFlow

JavaArraysandS

trings