University of Toronto at Scarborough © Kersti Wain-Bantin CSCC40 classes 1

classes

a class describes a group of objects with:• similar properties (attributes)• common behavior• common relationships to other objects• common meaning

class diagrams show classes with their attributes and operations, together with the associations between classes

University of Toronto at Scarborough © Kersti Wain-Bantin CSCC40 classes 2

what might be a class?

concepteventorganizationpersonplacephysical itembusiness conceptlogical entityapplicationcomputerbehavior

inventory systemreplenishmentsalesupplierstock clerkloading dockitem for salepurchase orderstorage patternphysical countscannerstale dating

airline reservation systemreservationarrivaltravel agencycustomertravel officeaircraftreservationflight timetablereservation transactionindexreservation cancellation

University of Toronto at Scarborough © Kersti Wain-Bantin CSCC40 classes 3

finding classes in use cases

• look for nouns and noun phrases in the description of the use cases

• include them in the model if they explain the nature or structure of information in the application

• but don’t create concepts which:• are beyond the scope of the system• refer to the system as a whole• duplicate other classes• are too vague or specific (few instances)

University of Toronto at Scarborough © Kersti Wain-Bantin CSCC40 classes 4

describing a class

name of object

responsibilities

operations

attributes

unique simple name or path name (if it’s in a

package)

named property describing the range of

values instances may hold

behaviors the class can exhibit

contract or obligation the class may have

op

tion

al

University of Toronto at Scarborough © Kersti Wain-Bantin CSCC40 classes 5

class namename of object

responsibilities

operations

attributes

name of object

simple name e.g. order, customer, campaignpath name e.g. business rules::FraudAgent,

java::awt::Rectangle

A package is a general purpose mechanism for organizing elements (in this case classes) into groups

client order

+OrderForm+TrackingForm-Order

University of Toronto at Scarborough © Kersti Wain-Bantin CSCC40 classes 6

attributesname of object

responsibilities

operations

attributesattributes

+ public = can access from other classes- private = cannot access from other classes# protected = can access from subclasses

Wall

+ material : string+ height : Float+ width : Float+ thinkness : Float+ isLoadBearing : Boolean = false- density : Float+ dateBuilt : Date

University of Toronto at Scarborough © Kersti Wain-Bantin CSCC40 classes 7

[visibility] name [multiplicity] [: type] [= initial-value] [{property-string}]

visibilityname

multiplicitytype

initial-valueproperty-string

+ (public), # (protected), - (private)e.g. CustomerName, DiscountRatee.g. [0..1], [2..*]e.g. Point, String, Date, etc.e.g. =(0,0), = nullchangeable (default), addOnly, frozen

6 examples of legal attribute declarationsorigin origin : Point = (0,0)+ origin id : integer {frozen}origin : Point name : [0..1] : String

Booch, jacobson, Rumbaugh. The Unified Modeling Language User Guide. Addison Wesley. 1999. pg 127-128.

attribute declaration

University of Toronto at Scarborough © Kersti Wain-Bantin CSCC40 classes 8

operationsname of object

responsibilities

operations

attributes

operations

+ public # protected - private

( ) operation parameter

Patient

+ makeAppointment ( )

+ calculateLastVisit ( )

+ changeStatus ( )

+ provideMedicalHistory ( )

examples of operations • change the value of attributes• change state• change links• invoke other objects

University of Toronto at Scarborough © Kersti Wain-Bantin CSCC40 classes 9

operation signatures

[visibility] name [(parameter-list)] [ : return-type]

visibilityname

parameter-listreturn-type

+ (public), # (protected), - (private)e.g. restart, addStudentsee belowe.g. Integer, String, etc

each parameter looks like this[direction] name : type [= default-value]

directionnametype

default-value

in, out, inoute.g. getId, calculateBonusBoolean, Money, etc.e.g. 42, John

University of Toronto at Scarborough © Kersti Wain-Bantin CSCC40 classes 10

an example

parameters in signatures

returned value

Campaign

title : String

campaignStartDate : Date

campaignFinishDate : Date

estimatedCost : Money

actualCost : Money

completionDate : Date

datePaid : Date

completed (completionDate : Date,

actualCost: Money)

setFinishDate ( FinishDate : Date)

recordPayment ( datePaid : Date )

costDifference ( ) : Money

University of Toronto at Scarborough © Kersti Wain-Bantin CSCC40 classes 11

classes and instances

instance of a class

FoodCO:client

companyAddress= Evans Farm, NorfolkcompanyName=FoodCocompanyTelephone=4165551212

:client

anonymous instance of a class

(used in collaboration diagrams)

class

client

companyAddresscompanyNamecompanyTelephone

University of Toronto at Scarborough © Kersti Wain-Bantin CSCC40 classes 12

subclass 1

attributesspecific to this

subclass

subclass 2

attributesspecific to this

subclass

subclass 3

attributesspecific to this

subclass

superclass

attributes sharedby all subclasses

( denotes generalization )

classes and subclasses

University of Toronto at Scarborough © Kersti Wain-Bantin CSCC40 classes 13

types of classes

<<entity>>campaign

titlecampaignStartDatecampaignFinishDate

getCampaignAdvert()addNewAdvert()

boundary class entity class control class

<<control>>control::addAdvert

showClientCampaigns()showCampaignAdverts()createNewAdvert()

<<boundary>>user interface::AddAdvert

startInterface()assignStaff()selectClient()selectCampaign()

entityboundary control

University of Toronto at Scarborough © Kersti Wain-Bantin CSCC40 classes 14

salesStaff clientsales staff

liaises with1 0..*

staffPosition staffMemberis allocated to

1..* 0..*

memberPosition

University of Toronto at Scarborough © Kersti Wain-Bantin CSCC40 classes 15

links

FoodCO:client World Tradition:campaign

FoodCo is the client in the World Tradition campaign

and associations

staff members are assigned client(s)each client has one staff assigned to it

staffMember

staffNamestaffNostaffStartDate

client

companyNamecompanyAddressliaises with

1 0..*

University of Toronto at Scarborough © Kersti Wain-Bantin CSCC40 classes 16

class diagram

<<boundary>>user interface::assignStaff

startInterface()assignStaff()selectClient()selectCampaign()

<<control>>control::assignStaff

assignStaff()getClientCampaign()showCampaignStaff()

<<entity>>client

companyNamecompanyAddresscompanyTelephone

getClientCampaign()getClients()

<<entity>>campaign

titlecampagnStartDatecampaignFinishDate

getCampaignStaff()assignStaff()

<<entity>>staffMember

staffNo()staffName()staffStartDate()

getStaff()assignStaff()getStaffDetails()

1 assigned to 0..*1 places 0..*

University of Toronto at Scarborough © Kersti Wain-Bantin CSCC40 classes 17

booking

roomTypeAvailability : Integer

reserveAccomodation (date, duration, roomType, guestName)freeAccommodation (date, duration, roomType)getAvailable (date, duration, roomType)decreaseAvailability (date, duration, roomType)confirmReservation (reservationNumber)fillReservation(reservation)checkInGuest (guestName)cancelReservation (reservationNumber)showReservation (startDate, reservationState)showAvailability (date, duration, roomType)showRoomRate (roomType)showReservation (reservationNumber)showRoomDirections (room)

room

roomTypeAvailability :Integer

occupy (guestName)findVacant (roomType)

guest

name:Stringaddress : StringcarRegNumber: String

reservation

status: Integerdate: Dateduration: IntegerroomType: Integer

create (startDate, duration, roomType, customerName)makProvisionalConfirmExercisecancelcalculatePrice (discountPercent)getDetails (startDate, Duration, roomType, customerName)allocateCustomer (customerRef)allocateRoom (roomNumber, guestName)

customername: Stringaddress: StringpercentageDsicount::Integer

findDiscount()

1

1..*

1..*1

1

1..*

0..*1

class diagram

University of Toronto at Scarborough © Kersti Wain-Bantin CSCC40 classes 18

class diagram

takes

*

required_for

required_by

*

0..* 0..*

11

<<entity>>student

<<PK>>student_id:Stringstudent_name:Stringcurrent_fees:Money

areYouValid(out s_check)addCourse(crsoffOID)feesPaid(out paid)

<<boundary>>user interface::ProgramEntryWindow

add(std, crs, sem)destroy()

<<entity>>prereqCourse

prereq_grade : String

prereq(out crsOID)

<<entity>>academicRecord

course_code : Stringyear : datesemester : Integergrade : String

prereqsSatisfied(out satisfied)

<<entity>>grade

grade : Stringmark : set<Nmber>

<<entity>>courseOffering

year : Datesemester : Integerenrolment_quota: I nteger

areYouOpen(out c_check)addStudent(stdOID)

<<entity>>course

<<PK>>course_code : Stringcourse_name : Stringcredit_points : Integer

areYouOpen(out c_check)preseq(out crs)addStudent(stdOID)

*

*

University of Toronto at Scarborough © Kersti Wain-Bantin CSCC40 classes 19

University of Toronto at Scarborough © Kersti Wain-Bantin CSCC40 classes 20

Class-Responsibility-Collaboration cards 

 

 

CLASS NAME  

RESPONSIBILITIES COLLABORATING CLASSES

operation 1operation 2operation 3etc.

class Anoneclass B, class C 

CRC cards

University of Toronto at Scarborough © Kersti Wain-Bantin CSCC40 classes 21

actor action

1.0 enter customerNumber

2.0 enter itemCode

3.0 enter itemQuantity

4.0 indicate order is complete

E1.0 enter customerNumber

E1.1 select addCustomer

system response

display customerName

display itemDescription

display itemPrice

display orderAmount and orderNumber

display “not found” message

offer selection of exit or add customer

invoke addCustomer

excep

tion

s

basic

flow