Z00040000120144014COMP6178 Session13_Introduction to OOP Concept

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Introduction to OOP Concept

Session 13

COMP6178 Introduction to Programming


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Introduction to OOP

Class and Object

Method

Encapsulation Inheritance

Polmorphism

Outline

!ina "usantara

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Introduction to OOP

Object Oriented Programming $OOP% is a techni&ue tocreate object'oriented programs(

)n object described b entities in the real *orld thatcan be clearl identi+ed( E,ample- students. cars.

des/s and other things that can be 0ie*ed as objects( Objects in programming languages must ha0e the

beha0ior method. propert. tpe. and identit(

)ll data and 2unctions *rapped in classes and objects(

OOP pro0ides the 2acilit to *rite a program to change

the actual object in the component programming code(

!ina "usantara

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!ina "usantara

)d0antage o2 OOP

)n object'oriented languages such as 4a0acombine language s/ills in the procedure badding a dimension that pro0ides- more

5e,ible. clear. easier to use bac/ throughabstraction. encapsulation. inheritance. andpolmorphism(

Other ad0antage o2 OOP -

)llo*s the use o2 real *orld modeling upport the reuse o2 e,isting code

Pro0ide 5e,ibilit in modi2ing e,isting applications

)ssist *ith ease o2 maintenance o2 e,isting code


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e+ning Classes or Objects

)n object represent an entit in the real *orld

)n object has the properties and beha0ior- Properties- something that characteri9e the object

!eha0ior- something that as/ the object to per2orm anaction

Objects o2 the same tpe are de+ne using acommon class

)n object is an instance o2 a class

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Class and Object E,amples

Class - Collection o2 data de+nitions and methodsin the unit 2or a particular purpose( ) template is ablueprint that de+nes *hat data objects andmethods(

Object- a representation o2 Class Class E,ample-

a man. *ho has a name. age. height. *eight. and color andhair tpe $data objects nature% and also to eat. *al/. pla.and sleep $beha0ior method%(

Object E,ample- !ernard is 1: ears old 17;cm tall.*eight 7; /g. blac/ curl hair. an acti0it as eating.sleeping. plaing and roads(

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E,ample Class and ObjectclassPupp?

publicPupp $Stringname%?

ni0ersit

:


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Constructor

) class contains constructors that are in0o/ed tocreate objects 2rom the class blueprint(

Constructor declarations loo/ li/e method

declarations e,cept that the use the name o2 theclass and ha0e no return tpe(

!ina "usantara >ni0ersit

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E,ample Constructor or e,ample. !iccle has one constructor-

public class !iccle?

private int gearB

private int cadenceB

privateintspeedB

public!iccle $intstartCadence. intstartpeed. intstartHear% ?gear F startHearB

cadence F startCadenceB

speed F startpeedB

publicstaticvoidmain$StringD args%?

Bicycleobj F ne* Bicycle(. 1;. 1%B calling constructor


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estructor

!ecause 4a0a is a garbage collected language oucannot predict *hen $or e0en i2% an object *ill bedestroed( ence there is no direct e&ui0alent o2a destructor(


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Methods

)bilit o2 objects

)ll *or/ processes and beha0ior o2 an objectrepresenteddescribed b this method(

E,ample- People can tal/as/. *al/. eat. sleepand rest(

!ina "usantara

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E,ample Method!eha0iorpublicclassMotorccle?

voidstartEngine$% ?

i!$enginetate FF true% stem(out(println$@


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Method )bstraction and Encapsulation

Method abstraction is achie0ed b separating theuse o2 method 2rom its implementation(


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E,ample o2 EncapsulationpublicclassEncapsulation?

privateStringnameB

privateintageB

publicintget)ge$%?

returnageB

publicStringget"ame$%?

returnnameB

publicvoidset)ge$ intne*)ge%?

age F ne*)geB

publicvoidset"ame$Stringne*"ame%?

name F ne*"ameB


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Inheritance

Object oriented programming allo*s ou to deri0ene* classes 2rom e,isting classes inheritance(

Can be used to a0oid redundanc. ma/e the sstemeas to comprehend. and eas to maintain(

Can use a class to model objects o2 the same tpe(

Inheritance enable ou to de+ne a general class andlater e,tend it to more speciali9ed classes(


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E,ample o2 Inheritance

publicclassAnimal{

}

publicclassMammal extendsAnimal{

}

publicclassReptile extendsAnimal{

}

publicclassDog extendsMammal{

}


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Lisibilit modi+er O2ten /no*n b 0isibilit or accessibilit modi+er


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Modi+ers


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Polmorphism One method has man implementations beha0ior


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!ina "usantara

E,ample o2 Polmorphism

public interface Vegetarian{}

public class Animal{}

public class Deer extends Animal implements

Vegetarian{}

Polmorphism in ja0a using /e*ord inter2ace toma/e beha0ior 2or implement in class


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!ina "usantara

E,ercise

1( escribe and gi0e e,ample using class andobject

J( Nhat are the dierences bet*een constructors

and methods#( E,plain the dierence bet*een method

o0erloading and method o0erriding Hi0ee,ample 2or method o0erloading and methodo0erriding

3( Nhat is /e*ord superand t#isin ja0a Canou gi0e e,ample

K( oes ja0a can use multiple inheritance Nh


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!ina "usantara

e2erences

aniel Qiang. R(. J;11. Introduction to javaprogramming. 0ol(;8. Pearson Education."e* 4erse( Chapter 7. :. 1;(

http-ja0a(sun(comdocsboo/stutorialja0aconceptsinde,(html
http://java.sun.com/docs/books/tutorial/java/concepts/index.htmlhttp://java.sun.com/docs/books/tutorial/java/concepts/index.htmlhttp://java.sun.com/docs/books/tutorial/java/concepts/index.htmlhttp://java.sun.com/docs/books/tutorial/java/concepts/index.html

Z00040000120144014COMP6178 Session13_Introduction to OOP Concept

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