J & K STATE BOARD OF SCHOOL EDUCATION - JKBOSE

Pablo Oliveira <[e-mail]>

Description

ROLL NAMESr J & K STATE BOARD OF SCHOOL EDUCATION E T T Annual 1ST Year Exam -2009-11 Result(Annual Reg) Notification No. -006 , Dated : 01/12/2011 Jammu Province) 1st Year Result Sr ROLL NAME 1st Year Result 101407 NAVEEN 1 Re(PPE,TLE) 101412 KASHMIR SINGH 2 Re(SPE,TLM,TLS,TLC,T LE,TLH,TPM,TPS,TPC,T PE,TPH,HPE) 101413 BALVINDER SINGH 3 Re(TLE) 101428 NEELAM DEVI 4 (Pass - 542) 101429 BLINDER SINGH 5 (Pass - 494) 101430 PRIYANKA 6

• rehan khan
• prasad kumhar
• deep mala
• assistant secretary
• sr roll name
• annual reg
• -11 result

Sujets

• Bishnoï
• Patidar
• Kumari
• Ibrahim
• Result
• Kumhar
• Assistant
• Annual

Informations

• Publié par: urmi
• Nombre de lectures: 98

Extrait

ComputerScienceIntroductoryCourseMSc-IntroductiontoJava

ComputerScienceIntroductoryCourseMSc- IntroductiontoJava Lecture2:ObjectOrientedProgramming

PabloOliveira <[e-mail]>

ComputerScienceIntroductoryCourseMSc-IntroductiontoJava

Outline

1 References

2 Inheritance

3 Encapsulation

4 Polymorphism

5 Interfaces

6 Summary

TSNE

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Introduction:ObjectOrientedProgramming

Inthelastlecturewelearnedthatwecanstructureprogramsusing objectsofmanyclasses. InthislecturewewillexamineOOPconceptsinmoredetail: constructors: creatingnewobjects. references: designatingobjects. inheritance: creatingfamiliesofclasses. encapsulation: hidingimplementation. polymorphism: factorizingcommonbehaviours. interfaces: behavioralcontracts.

ComputerScienceIntroductoryCourseMSc-IntroductiontoJava

Constructors:creatinganewobject

Definition Constructorsarespecialmethodsthatarecalledtocreateanewinstance oftheirclass.

class BankAccount { int balance; BankAccount() { balance=0; } BankAccount( int initialDeposit) { balance=initialDeposit; }

}

account1= new BankAcconut(); account2= new BankAccount(100);

ComputerScienceIntroductoryCourseMSc-IntroductiontoJava References

Outline

1 References

2 Inheritance

3 Encapsulation

4 Polymorphism

5 Interfaces

6 Summary

ComputerScienceIntroductoryCourseMSc-IntroductiontoJava References

References

Whenavariableisassignedaprimitivetypeitcontainsavalue. Whenassignedanobject,arrayorstring,itcontainsareferenceto thedata. Ifaiscopiedorpassed,oldandnewreferencespointtothe same originalobject .

staticvoid changeValues( int anArray[], int value) { anArray[0]=42; value=42; } publicstaticvoid main(Stringargs[]) { int v=0; int []a= { 0,0 } ; System.out.println(v+””+a[0]+””+a[1]); changeValues(a,v); System.out.println(v+””+a[0]+””+a[1]); } output: 000 0240

ComputerScienceIntroductoryCourseMSc-IntroductiontoJava References

Immutability

Stringareaspecialcase,becausetheyareimmutable(cannotbe changed). WhenyouchangeaStringanewdifferentStringiscreatedandthe charactersoftheorignalonearecopied. Forperformance:donotbuildastringwithconcatenation,use StringBuilder.

publicstaticvoid main(Stringargs[]) { Strings1=”hello”; Strings2=s1; s1=s1+”!”; System.out.println(s1+””+s2); }

output: hello!hello

ComputerScienceIntroductoryCourseMSc-IntroductiontoJava Inheritance

Outline

1 References

2 Inheritance

3 Encapsulation

4 Polymorphism

5 Interfaces

6 Summary

ComputerScienceIntroductoryCourseMSc-IntroductiontoJava Inheritance

Inheritance

Q:Rememberourturtle?Itcouldturnandadvance.Butwewantanew classCrabthatadvancessideways... WecouldwriteanewclassCrab,buttherewouldalotofcodein commonwithTurtle(whichmakesthecodebasedifficultto maintain). Wearegoingtouse inheritance . Inheritancemakesitpossibletocreatea subclass thatinheritsthe propertiesofitsancestoror superclass .

Animal

TurtleCrab

RedCrab

ComputerScienceIntroductoryCourseMSc-IntroductiontoJava Inheritance

Inheritance

class Animal { Colorcolor; Positionposition; double rotation;

void turn( double angle) {} ; void advance() {} ; }

class Crab extends Animal { void advance() { / ∗ codeformovingsideways ∗ / } }

Crabcrab= new Crab(); crab.color=Color.BLUE; crab.advance();

superclass

subclass

ComputerScienceIntroductoryCourseMSc-IntroductiontoJava Inheritance

overridingandhiding

Whatwejustdidwithmethodadvanceiscalled overriding . Whenwecall crab.advance() thecrab’sadvanceiscalled! Theanimal’sadvancehasbeenoverrided. Ifamethodisnotoverriden,thesuperclass’isused(here crab.turn(10); wouldcallAnimal’sturnimplementation. the final keywordinamethoddeclarationindicatesthatthe methodcannotbeoverridden. overridingastaticmethodoravariableiscalled hiding ,becausethenew staticimplementationorvariable hides theoldone,doingthisisusuallya badidea.

ComputerScienceIntroductoryCourseMSc-IntroductiontoJava Inheritance

thisandsuper

foragivenclass this representsthecurrentclassand super the superclass. superisusedtocalloverridensuperclass’methods.

class Animal { void advance(); }

class Crab extends Animal { Stringname; advance() { this .turn(90); super .advance(); this .turn( − 90); } }

ComputerScienceIntroductoryCourseMSc-IntroductiontoJava Inheritance

class Animal { Positionposition; double rotation;

Animal(Positionposition, double rotation) { this .position=position; this .rotation=rotation; }

}

class Crab extends Animal { Stringname; Crab(Positionposition) { super (position,90); } Crab(Positionposition,Stringname) { this (position); this .name=name; }

}

InheritanceandConstructors

InjavaalltheclassesaresubclassesoftheObjectclass. Asubclassconstructorwillalwayscallasuperclassconstructor. Ifaclasspossessnoconstructor,anemptyonewithnoparameters isimplicit. Everyconstructorofasubclasscalltheno-parameterssuperclass constructor. Butwecancontrolthiswith super and this keywords.

Object()

RedCrab(Stringname)

Animal()

Crab()Crab(Stringname)

ComputerScienceIntroductoryCourseMSc-IntroductiontoJava Inheritance

ComputerScienceIntroductoryCourseMSc-IntroductiontoJava Inheritance

abstractmethods

Supposeweaddbirdstoourclasshierarchy. birdsandcrabsdonotmovethesameway...thereisnocommon implementationforadvancethatwecanputinAnimals. wecouldcreateanempty advance() inthe Animal classand overrideitin Bird and Crab . Yet,anotherprogramercouldaddanewsubclassandforgetto implementthe advance() method. Thus,weuse abstractmethods .

Definition

Anabstractmethodisamethodwhichhasnoimplementation. Anabstractclassisaclasswithabstractmethods. Itismandatoryforallthenon-abstractsubclassestooverrideallthe abstractmethods. Anabstractclasscannotbeinstantiated.

ComputerScienceIntroductoryCourseMSc-IntroductiontoJava Inheritance

abstractclass Animal { Positionposition; double rotation;

abstractvoid advance();

}

class Crab extends Animal { Stringname; void advance() { / ∗ crabmoves ∗ / } }

Animala= new Animal(); //COMPILATIONERROR Crabc= new Crab(); //Works!

ComputerScienceIntroductoryCourseMSc-IntroductiontoJava Encapsulation

Outline

1 References

2 Inheritance

3 Encapsulation

4 Polymorphism

5 Interfaces

6 Summary

ComputerScienceIntroductoryCourseMSc-IntroductiontoJava Encapsulation

Encapsulation

Definition Encapsulationistheactofhidingpropertiesandmethodsinsideaclass.

Thisallowstoprotectclassesfromunexpectedside-effectsfromthe outside. Italsoenforcesimplementationagnosticprogramming,whichisa goodidea.

ComputerScienceIntroductoryCourseMSc-IntroductiontoJava Encapsulation

Packages

Definition A package isagroupofclasses. Packagesdefinea namespace . Classesinthesamepackagesharethesame namespace .

package Animals; class Animal {} class Crab {}

import Animals.Crab; import Animals. ∗ ; class MyProgram {}

ComputerScienceIntroductoryCourseMSc-IntroductiontoJava Encapsulation

Accesmodifiers

Injavaencapsultationisobtainedthroughacces/visibilitymodifiers . Classescanbe public ,visiblebyeveryone or withoutmodifier inwhichcasetheyareonlyvisibleinsidetheir package(agroupofclasses). Classmembers(variablesandmethods)canhave4modifierswith differentdegreesofvisibility.

ModifierClassPackageSubclassWorld publicYYYY protectedYYYN nomodifierYYNN privateYNNN

ComputerScienceIntroductoryCourseMSc-IntroductiontoJava Encapsulation

packagesanimals; class Animal { privatedouble rotation; publicvoid turn( double angle) { position+=angle; } } class Crab extends Animal { publicvoid turnBack() { turn(180); //legal rotation+=180; //illegal } }

ComputerScienceIntroductoryCourseMSc-IntroductiontoJava Polymorphism

Outline

1 References

2 Inheritance

3 Encapsulation

4 Polymorphism

5 Interfaces

6 Summary