Object Oriented Paradigm ( Java )

7/23/2019 Object Oriented Paradigm ( Java )

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Object Oriented Paradigm

(Java)

S.S.R.K.M.GUPTA. M.Tech. (M.Phil.)

Aditya !llege !" #ngineering $Techn!l!gy

S%ram&alem'*+


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S!"t,are cri-i- in /+0(U.S.A)


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Relative !-t1#2!rt in di2erent &ha-e-


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!-t !" Maintenance &ha-e


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A 3!!4 !n Pr!ced%re !riented lang%age


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5ra,bac4- !" POP lang%age-

6+ 7 !" &r!ject c!-t ha- t! %tili8ed in Maintenance&ha-e.

S!"t,are maintenance can be di9c%lt and timec!n-%ming.

:hen change- are made t! the main &r!ced%re (t!&);

th!-e change- can ca-cade t! the -%b &r!ced%re- !"main; and the -%b'-%b &r!ced%re- and -! !n; ,here thechange may im&act all &r!ced%re- in the &yramid.

5eb%gging i- very di9c%lt i" line- !" c!de cr!--e-

0;000; and &r!grammer l!!-e- hi- c!ntr!l !n c!de. Thi- a&&r!ach d!e- n!t m!del real ,!rld &r!blem- very

,ell.

Gl!bal data i- acce--ible by all "%ncti!n-; thi- lead- t!

b%g-.


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/

Str%ct%red v- OO #


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A '&r!gram %-ing Str%ct%re


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>%ncti!n- are called thr!%gh !bject-


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#ach !bject ha- it- !,n -tate%-ed by it- "%ncti!n-


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What is an Object?

An !bject i- a -!"t,are b%ndle !" related variable-and meth!d-. S!"t,are !bject- are !"ten %-ed t!m!del real',!rld !bject- y!% ?nd in everyday li"e.

@i-%al re&re-entati!n !" a -!"t,are !bject A bicycle m!deled a- a

-!"t,are !bject

Object (Agent) in the ,!rld


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t i- an entity,ith a ,ell'

de?nedb!%ndary andidentity that

enca&-%late--tate andbehavi!r.

Operations

Attributes

Object


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t i- !ne !" the&!--ible c!nditi!n-that an !bject may

e


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t determine-h!, an !bject

act- andreact-.

t i-

re&re-ented bythe !&erati!n-that the !bjectcan &er"!rm.

Joel Santos

Enrolls()

updateSquad()

ObjectB- =ehavi!r


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Alth!%gh t,! !bject- may -hare

the -ame -tate (attrib%te- andrelati!n-hi&-); they are -e&arate;inde&endent !bject- ,ith their !,n

%niC%e identity.

AthleteID: 3556Name Joel SantosStatus:NEW

Squad:None

AthleteID: 3557Name: Arja SolamoStatus:NEW

Squad:None

ObjectB- dentity


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n 'lang%age; data i- n!t -ec%redand ea-ily c!rr%&ted by !ther-

ac ! ec - a a cann! e


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ac ! ec - a a cann! ec!rr%&ted

by !ther- in !ther cla--


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>eat%re- !" Object !riented

&aradigm


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A ,ay !" @ie,ing the :!rld

Agent- and !mm%nitie- Me--age- and Meth!d-

Re-&!n-ibilitie-

la--e- and n-tance-

la-- Eierarchie-'nheritance

Meth!d =inding; Overriding; and

#


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FF

Sending >l!,er- t! a >riend

S%&&!-e (Ravi) ,i-h t! -end !,er- t! a"riend; (@en% ); ,h! live- in a city many

mile- a,ay.

:hat -h!%ld d!H


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F

The c!mm%nity !" agent-hel&ing me

Venus Florist (Prasad)

Agent (Mahesh)

Me (Ravi)

Delivery Person

Friend (Venu)

Flower Arranger

Wholesaler

Grower

Gardener


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F*

An Ob-ervati!n

An !bject'!riented &r!gram i--tr%ct%red a- a c!mm%nity !"interacting agent-; called !bject-. #ach !bject ha- a r!le t! &lay.

#ach !bject &r!vide- a -ervice; !r&er"!rm- an acti!n; that i- %-ed by !ther

member- !" the c!mm%nity.


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F

Agent- and !mm%nitie- S!l%ti!nI >ind an a&&r!&riate agent; namely Mahe-h;

and &a-- t! him a me--agec!ntaining my reC%e-t t i- the re-&!n-ibility!" Mahe-h t! -ati-"y my reC%e-t

There i- -!me meth!d -!me alg!rithm !r -!me -et !"!&erati!n- %-ed t! -ati-"y my reC%e-t

Thi- in"!rmati!n; i.e.; detail-; i- %-%ally hidden"r!m myin-&ecti!n.

An !bject'!riented &r!gram i- -tr%ct%red a- ac!mm%nity !" interacting agent-; called !bject-

#ach !bject ha- a r!le t! &lay

#ach !bject &r!vide- a -ervice; !r &er"!rm- anacti!n; that i- %-ed by !ther member- !" thec!mm%nity


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:hat i- a me--age in OOPH

A reC%e-t "!r an !bject t! &er"!rm !ne !" it-!&erati!n- (meth!d-)

:hat i- a Me--ageH S!"t,are !bject- interact and c!mm%nicate ,ith

each !ther %-ing me--age-.

The !bject t! ,hich the me--age i- addre--ed(!%r=icycle)

The name !" the meth!d t! &er"!rm (changeGear-)

Any &arameter- needed by the meth!d (l!,erGear)


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Me--age- and Meth!d-

Acti!n- i- initiated in !bject'!riented &r!gramming bythe tran-mi--i!n !" a me--age t! an agent (an !bject)re-&!n-ible "!r the acti!n

The me--age enc!de- the reC%e-t "!r an acti!n

t i- acc!m&anied by any additi!nal in"!rmati!n(arg%ment-) needed t! carry !%t the reC%e-t

The receiver i- the !bject t! ,h!m the me--age i--ent

" the receiver acce&t- the me--age; it acce&t- the

re-&!n-ibility t! carry !%t the indicated acti!n n re-&!n-e t! a me--age; the receiver ,ill &er"!rm

-!me meth!d t! -ati-"y the reC%e-t


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Re-&!n-ibilitie-

n !bject !riented &r!gramming acti!n- are de-cribed interm- !" re-&!n-ibilitie-.

A reC%e-t t! &er"!rm an acti!n den!te- t! &er"!rm a ta-4t! get de-ired re-%lt.

:hen a &r!blem i- eval%ated in term- !" re-&!n-ibilitie-;

the ab-tracti!n level ,ill be increa-ed. The !bject- th%- bec!me inde&endent "r!m each !ther

,hich ,ill hel& in -!lving c!m&le< &r!blem-.

An !bject ha- a c!llecti!n !" re-&!n-ibilitie- related ,ith

it ,hich termed a- L&r!t!c!lD. t i- im&!rtant that !bject- be all!,ed t! &er"!rm their

ta-4 h!,ever they -ee ?t; ,ith!%t %nnece--aryinteracti!n- !r inter"erence ,ith !ther !bject-


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la--e- and n-tance- #very !bject i- in-tance!" a cla--. A cla--

gr!%&- -imilar !bject-.

The cla-- i- the re&!-it!ry "!r behavi!ra--!ciated ,ith an !bject.

The meth!d inv!4ed by an !bject in re-&!n-et! a me--age i- determined by the cla-- !"the receiver.

=ehavi!r i- a--!ciated ,ith cla--e-; n!t ,ith

individ%al in-tance-. All !bject- that arein-tance- !" a cla-- %-e the -ame meth!d inre-&!n-e t! -imilar me--age-.

A l hi h f i


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0

A class hierarchy of variousmaterial objects

Material Obe!t

Ani"al

Ma""al

#u"an

$ho%&ee%er

Florist

Flora

Artist Dentist

Painter

'i Ada"

Dog

Flash

Platy%us

Phyl

Plant

Flower

arnation

$allys Flowers

More abstra!t !lasses are listed near the to% o* the treeMore s%e!i*i! !lasses and individuals are listed near the botto"+


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la-- Eierarchie- la--e- are arranged in a treeli4e -tr%ct%re called a hierarchy

A cla-- may have -everal ance-t!r-; %& t! root class

:hen y!% de?ne a -%b cla--; y!% -&eci"y it- -%&ercla--

#very cla-- may have 8er! !r m!re -%bcla--e-

The &rinci&le that 4n!,ledge !" a m!re general categ!ry i-al-! a&&licable t! a m!re -&eci?c categ!ry i- calledinheritance.

The cla-- !lor"st,ill inherit attrib%te- !" the cla-- (!rcateg!ry) Shop#eeper.

la--e- can be !rgani8ed int! a hierarchical inheritance-tr%ct%re.

A child cla--(!r -%bcla--) ,ill inherit attrib%te- "r!m a&arent cla--higher in the hierarchy. An ab-tract &arent cla--i- a cla-- "!r ,hich there are n! direct in-tance- it i- %-ed

!nly t! create -%bcla--e-.


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Inheritance


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nheritance ' termin!l!gy

Inheritance is a fundamental Object Oriented concept that a newclass acquires the features from another existing class, whichreflects reusability. nheritance all!,- &r!grammer t! de?ne a general cla--

3ater y!% de?ne a m!re -&eci?c cla-- Add- ne, detail- t! general de?niti!n

Ne, cla-- inherit- all &r!&ertie- !" initial; general cla--

A class can be defined as a "subclass" of another class.

The -%bcla-- inherit- all data attrib%te- !" it- -%&ercla--

The -%bcla-- inherit- all meth!d- !" it- -%&ercla--

The -%bcla-- inherit- all a--!ciati!n- !" it- -%&ercla-- The subclass can:

Add ne, "%ncti!nality

U-e inherited "%ncti!nality

Override inherited "%ncti!nality


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An e


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Meth!d binding

=inding i- ,hat ha&&en- ,hen a meth!dinv!cati!n i- b!%nd t! an im&lementati!n nv!lve- l!!4%& !" the meth!d in the cla--; !r !ne

!r it- &arent-

=!th meth!d name- and &arameter- are chec4ed =inding can ha&&en at t,! di2erent time-

!m&ile time ' -tatic binding ( !r ) #arly binding

R%n time ' dynamic binding ( !r ) 3ate binding

Java al,ay- -%&&!rt- t! dynamicbinding by de"a%lt.


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Meth!d =inding

Object- are %-ed t! call meth!d-. Method Bindingi- an !bject that can be %-ed t! call

an arbitrary &%blic meth!d; !n an in-tance that i-acC%ired by eval%ating the leading &!rti!n !" ameth!d binding e


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Meth!d =inding ' #


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Meth!d Overriding


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Meth!d Overriding

. S%b cla-- can !verride the meth!d- de?ned by the -%&er cla--.

F. Overridden Meth!d- in the -%b cla--e- -h!%ld have -amename; -ame -ignat%re ; -ame ret%rn ty&e and may have eitherthe -ame !r higher -c!&e than -%&er cla-- meth!d.

. Java im&lement- R%n Time P!lym!r&hi-m1 5ynamic Meth!d

5i-&atch by Meth!d Overriding. 3ate =inding

*. all t! Overridden Meth!d- i- Re-!lved at R%n Time.

. all t! a !verridden meth!d i- n!t decided by the ty&e !"re"erence variable Rather by the ty&e !" the !bject ,here

re"erence variable i- &!inting.6. :hile Overriding a Meth!d; the -%b cla-- -h!%ld a--ign either

-ame !r higher acce-- level than -%&er cla-- meth!d.


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#


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#


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#


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Summary of Object OrientedProgramming

#verything i- an !bject

Object- &er"!rm c!m&%tati!n by ma4ingreC%e-t- !" each !ther thr!%gh the &a--ing !"me--age-

#very !bject ha- itB- !,n mem!ry; ,hichc!n-i-t- !" !ther !bject-.

#very !bject i- an in-tance !" a cla--. A cla--gr!%&- -imilar !bject-.

The cla-- i- the re&!-it!ry "!r behavi!ra--!ciated ,ith an !bject

la--e- are !rgani8ed int! -ingly'r!!ted tree-tr%ct%re; called an inheritance hierarchy.

Object Oriented Paradigm ( Java )

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