Class diagram - Wikipedia

In software engineering, a class diagram in the Unified Modeling Language (UML) is a type of static structure diagram that describes the structure of a ... Classdiagram FromWikipedia,thefreeencyclopedia Jumptonavigation Jumptosearch Typeofstaticstructurediagram Thisarticleneedsadditionalcitationsforverification.Pleasehelpimprovethisarticlebyaddingcitationstoreliablesources.Unsourcedmaterialmaybechallengedandremoved.Findsources: "Classdiagram" – news ·newspapers ·books ·scholar ·JSTOR(February2009)(Learnhowandwhentoremovethistemplatemessage)UMLdiagramtypes StructuralUMLdiagrams Classdiagram Componentdiagram Compositestructurediagram Deploymentdiagram Objectdiagram Packagediagram Profilediagram BehavioralUMLdiagrams Activitydiagram Communicationdiagram Interactionoverviewdiagram Sequencediagram Statediagram Timingdiagram Usecasediagram vte HierarchyofUML2.5Diagrams,shownasaclassdiagram.Theindividualclassesarerepresentedjustwithonecompartment,buttheyoftencontainuptothreecompartments.Insoftwareengineering,aclassdiagramintheUnifiedModelingLanguage(UML)isatypeofstaticstructurediagramthatdescribesthestructureofasystembyshowingthesystem'sclasses,theirattributes,operations(ormethods),andtherelationshipsamongobjects. Theclassdiagramisthemainbuildingblockofobject-orientedmodeling.Itisusedforgeneralconceptualmodelingofthestructureoftheapplication,andfordetailedmodeling,translatingthemodelsintoprogrammingcode.Classdiagramscanalsobeusedfordatamodeling.[1]Theclassesinaclassdiagramrepresentboththemainelements,interactionsintheapplication,andtheclassestobeprogrammed. Inthediagram,classesarerepresentedwithboxesthatcontainthreecompartments: Thetopcompartmentcontainsthenameoftheclass.Itisprintedinboldandcentered,andthefirstletteriscapitalized. Themiddlecompartmentcontainstheattributesoftheclass.Theyareleft-alignedandthefirstletterislowercase. Thebottomcompartmentcontainstheoperationstheclasscanexecute.Theyarealsoleft-alignedandthefirstletterislowercase. Aclasswiththreecompartments.Inthedesignofasystem,anumberofclassesareidentifiedandgroupedtogetherinaclassdiagramthathelpstodeterminethestaticrelationsbetweenthem.Indetailedmodeling,theclassesoftheconceptualdesignareoftensplitintosubclasses. Inordertofurtherdescribethebehaviorofsystems,theseclassdiagramscanbecomplementedbyastatediagramorUMLstatemachine.[2] Contents 1Members 1.1Visibility 1.2Scope 2Relationships 2.1Instance-levelrelationships 2.1.1Dependency 2.1.2Association 2.1.3Aggregation 2.1.4Composition 2.1.5DifferencesbetweenCompositionandAggregation 2.2Class-levelrelationships 2.2.1Generalization/Inheritance 2.2.2Realization/Implementation 2.3Generalrelationship 2.3.1Dependency 2.4Multiplicity 3Analysisstereotypes 3.1Entities 4Seealso 5References 6Externallinks Members[edit] UMLprovidesmechanismstorepresentclassmembers,suchasattributesandmethods,andadditionalinformationaboutthemlikeconstructors. Visibility[edit] Tospecifythevisibilityofaclassmember(i.e.anyattributeormethod),thesenotationsmustbeplacedbeforethemembers'name:[3] + Public - Private # Protected ~ Package Aderivedpropertyisapropertywhosevalue(orvalues)isproducedorcomputedfromotherinformation,forexample,byusingvaluesofotherproperties. Aderivedpropertyisshownwithitsnameprecededbyaforwardslash'/'.[4] Scope[edit] TheUMLspecifiestwotypesofscopeformembers:instanceandclass,andthelatterisrepresentedbyunderlinednames.[5] Instancemembersarescopedtoaspecificinstance. Attributevaluesmayvarybetweeninstances Methodinvocationmayaffecttheinstance’sstate(i.e.changeinstance’sattributes) Classmembersarecommonlyrecognizedas“static”inmanyprogramminglanguages.Thescopeistheclassitself. Attributevaluesareequalforallinstances Methodinvocationdoesnotaffecttheclassifier’sstate Toindicateaclassifierscopeforamember,itsnamemustbeunderlined.Otherwise,instancescopeisassumedbydefault. Relationships[edit] UMLrelationsnotation Arelationshipisageneraltermcoveringthespecifictypesoflogicalconnectionsfoundonclassandobjectdiagrams.UMLdefinesthefollowingrelationships: Instance-levelrelationships[edit] Dependency[edit] Adependencyisatypeofassociationwherethereisasemanticconnectionbetweendependentandindependentmodelelements.[6]Itexistsbetweentwoelementsifchangestothedefinitionofoneelement(theserverortarget)maycausechangestotheother(theclientorsource).Thisassociationisuni-directional.Adependencyisdisplayedasadashedlinewithanopenarrowthatpointsfromtheclienttothesupplier. Association[edit] Classdiagramexampleofassociationbetweentwoclasses Anassociationrepresentsafamilyoflinks.Abinaryassociation(withtwoends)isnormallyrepresentedasaline.Anassociationcanlinkanynumberofclasses.Anassociationwiththreelinksiscalledaternaryassociation.Anassociationcanbenamed,andtheendsofanassociationcanbeadornedwithrolenames,ownershipindicators,multiplicity,visibility,andotherproperties.Therearefourdifferenttypesofassociation:bi-directional,uni-directional,aggregation(includescompositionaggregation)andreflexive.Bi-directionalanduni-directionalassociationsarethemostcommonones.Forinstance,aflightclassisassociatedwithaplaneclassbi-directionally.Associationrepresentsthestaticrelationshipsharedamongtheobjectsoftwoclasses. Aggregation[edit] ClassdiagramshowingAggregationbetweentwoclasses.Here,aProfessor'hasa'classtoteach. Aggregationisavariantofthe"hasa"associationrelationship;aggregationismorespecificthanassociation.Itisanassociationthatrepresentsapart-wholeorpart-ofrelationship.Asshownintheimage,aProfessor'hasa'classtoteach.Asatypeofassociation,anaggregationcanbenamedandhavethesameadornmentsthatanassociationcan.However,anaggregationmaynotinvolvemorethantwoclasses;itmustbeabinaryassociation.Furthermore,thereishardlyadifferencebetweenaggregationsandassociationsduringimplementation,andthediagrammayskipaggregationrelationsaltogether.[7] Aggregationcanoccurwhenaclassisacollectionorcontainerofotherclasses,butthecontainedclassesdonothaveastronglifecycledependencyonthecontainer.Thecontentsofthecontainerstillexistwhenthecontainerisdestroyed. InUML,itisgraphicallyrepresentedasahollowdiamondshapeonthecontainingclasswithasinglelinethatconnectsittothecontainedclass.Theaggregateissemanticallyanextendedobjectthatistreatedasaunitinmanyoperations,althoughphysicallyitismadeofseverallesserobjects. Composition[edit] Twoclassdiagrams.ThediagramontopshowsCompositionbetweentwoclasses:ACarhasexactlyoneCarburetor,andaCarburetorisapartofoneCar.Carburetorscannotexistasseparateparts,detachedfromaspecificcar.ThediagramonbottomshowsAggregationbetweentwoclasses:APondhaszeroormoreDucks,andaDuckhasatmostonePond(atatime).DuckcanexistseparatelyfromaPond,e.g.itcanlivenearalake.WhenwedestroyaPondweusuallydonotkillalltheDucks. TheUMLrepresentationofacompositionrelationshipshowscompositionasafilleddiamondshapeonthecontainingclassendofthelinesthatconnectcontainedclass(es)tothecontainingclass. DifferencesbetweenCompositionandAggregation[edit] Compositionrelationship 1.Whenattemptingtorepresentreal-worldwhole-partrelationships,e.g.anengineisapartofacar. 2.Whenthecontainerisdestroyed,thecontentsarealsodestroyed,e.g.auniversityanditsdepartments. Aggregationrelationship 1.Whenrepresentingasoftwareordatabaserelationship,e.g.carmodelengineENG01ispartofacarmodelCM01,astheengine,ENG01,maybealsopartofadifferentcarmodel.[8] 2.Whenthecontainerisdestroyed,thecontentsareusuallynotdestroyed,e.g.aprofessorhasstudents;whentheprofessordiesthestudentsdonotdiealongwithhim. Thustheaggregationrelationshipisoften"catalog"containmenttodistinguishitfromcomposition's"physical"containment. Class-levelrelationships[edit] Generalization/Inheritance[edit] ClassdiagramshowinggeneralizationbetweenthesuperclassPersonandthetwosubclassesStudentandProfessor Itindicatesthatoneofthetworelatedclasses(thesubclass)isconsideredtobeaspecializedformoftheother(thesupertype)andthesuperclassisconsideredaGeneralizationofthesubclass.Inpractice,thismeansthatanyinstanceofthesubtypeisalsoaninstanceofthesuperclass.Anexemplarytreeofgeneralizationsofthisformisfoundinbiologicalclassification:humansareasubclassofsimian,whichisasubclassofmammal,andsoon.Therelationshipismosteasilyunderstoodbythephrase'anAisaB'(ahumanisamammal,amammalisananimal). TheUMLgraphicalrepresentationofaGeneralizationisahollowtriangleshapeonthesuperclassendoftheline(ortreeoflines)thatconnectsittooneormoresubtypes. symbolicofrealization(subclass)_______▻(superclass) Thegeneralizationrelationshipisalsoknownastheinheritanceor"isa"relationship. Thesuperclass(baseclass)inthegeneralizationrelationshipisalsoknownasthe"parent",superclass,baseclass,orbasetype. Thesubtypeinthespecializationrelationshipisalsoknownasthe"child",subclass,derivedclass,derivedtype,inheritingclass,orinheritingtype. Notethatthisrelationshipbearsnoresemblancetothebiologicalparent–childrelationship:theuseofthesetermsisextremelycommon,butcanbemisleading. AisatypeofB Forexample,"anoakisatypeoftree","anautomobileisatypeofvehicle" Generalizationcanonlybeshownonclassdiagramsandonusecasediagrams. Realization/Implementation[edit] InUMLmodelling,arealizationrelationshipisarelationshipbetweentwomodelelements,inwhichonemodelelement(theclient)realizes(implementsorexecutes)thebehaviorthattheothermodelelement(thesupplier)specifies. TheUMLgraphicalrepresentationofaRealizationisahollowtriangleshapeontheinterfaceendofthedashedline(ortreeoflines)thatconnectsittooneormoreimplementers.Aplainarrowheadisusedontheinterfaceendofthedashedlinethatconnectsittoitsusers.Incomponentdiagrams,theball-and-socketgraphicconventionisused(implementorsexposeaballorlollipop,whereasusersshowasocket). Realizationscanonlybeshownonclassorcomponentdiagrams. Arealizationisarelationshipbetweenclasses,interfaces,componentsandpackagesthatconnectsaclientelementwithasupplierelement.Arealizationrelationshipbetweenclasses/componentsandinterfacesshowsthattheclass/componentrealizestheoperationsofferedbytheinterface. symbolicofrealization(implementer)-------▻(interface) Generalrelationship[edit] Classdiagramshowingdependencybetween"Car"classand"Wheel"class(Anevenclearerexamplewouldbe"CardependsonWheel",becauseCaralreadyaggregates(andnotjustuses)Wheel) Dependency[edit] Dependencycanbeaweakerformofbondthatindicatesthatoneclassdependsonanotherbecauseitusesitatsomepointintime. Oneclassdependsonanotheriftheindependentclassisaparametervariableorlocalvariableofamethodofthedependentclass.Sometimestherelationshipbetweentwoclassesisveryweak.Theyarenotimplementedwith membervariablesatall.Rathertheymightbeimplementedasmemberfunctionarguments. Multiplicity[edit] Thisassociationrelationshipindicatesthat(atleast)oneofthetworelatedclassesmakereferencetotheother.Thisrelationshipisusuallydescribedas"AhasaB"(amothercathaskittens,kittenshaveamothercat). TheUMLrepresentationofanassociationisalineconnectingthetwoassociatedclasses.Ateachendofthelinethereisoptionalnotation.Forexample,wecanindicate,usinganarrowheadthatthepointyendisvisiblefromthearrowtail.Wecanindicateownershipbytheplacementofaball,theroletheelementsofthatendplaybysupplyinganamefortherole,andthemultiplicityofinstancesofthatentity(therangeofnumberofobjectsthatparticipateintheassociationfromtheperspectiveoftheotherend). 0 Noinstances(rare) 0..1 Noinstances,oroneinstance 1 Exactlyoneinstance 1..1 Exactlyoneinstance 0..* Zeroormoreinstances * Zeroormoreinstances 1..* Oneormoreinstances Analysisstereotypes[edit] Entities[edit] Entityclassesmodellong-livedinformationhandledbythesystem,andsometimesthebehaviorassociatedwiththeinformation.Theyshouldnotbeidentifiedasdatabasetablesorotherdata-stores. Theyaredrawnascircleswithashortlineattachedtothebottomofthecircle.Alternatively,theycanbedrawnasnormalclasseswiththe«entity»stereotypenotationabovetheclassname. Seealso[edit] ExecutableUML ListofUMLtools Object-orientedmodeling Dependency(UML) Relateddiagrams Domainmodel Entity–relationshipmodel Objectdiagram References[edit] ^Sparks,Geoffrey."DatabaseModelinginUML".Retrieved8September2011. ^ScottW.Ambler(2009)UML2ClassDiagrams.Webdoc2003-2009.AccessedDec2,2009 ^UMLReferenceCard,Version2.1.2,HolubAssociates,August2007,retrieved12March2011 ^"UMLderivedpropertyispropertywhichvalueisproducedorcomputedfromotherinformation,forexample,byusingotherproperties".www.uml-diagrams.org.Retrieved2019-01-24. ^OMGUnifiedModelingLanguage(OMGUML)Superstructure,Version2.3:May2010.Retrieved23September2010. ^Fowler(2003)UMLDistilled:ABriefGuidetotheStandardObjectModelingLanguage ^"UMLTutorialpart1:classdiagrams"(PDF).Archivedfromtheoriginal(PDF)on2007-01-03.Retrieved2015-07-18. ^Goodwin,David."ModellingandSimulation,p.26"(PDF).TheUniversityofWarwick.Retrieved28November2015. Externallinks[edit] WikimediaCommonshasmediarelatedtoClassdiagram. IntroductiontoUML2ClassDiagrams UML2ClassDiagramGuidelines IBMClassdiagramIntroduction OMGUML2.2specificationdocuments UML2ClassDiagrams vteUnifiedModelingLanguageActors Organizations ObjectManagementGroup UMLPartners Persons GradyBooch IvarJacobson JamesRumbaugh ConceptsObjectoriented Object-orientedprogramming Object-orientedanalysisanddesign Object-orientedmodeling Structure Actor Attribute Artifact Class Component Interface Object Package Profilediagram Behavior Activity Event Message Method State Usecase Relationships Association Composition Dependency Generalization(orInheritance) Extensibility Profile Stereotype Other Multiplicity DiagramsStructure Class Component Compositestructure Deployment Object Package Behaviour Activity StateMachine Usecase Interaction Communications Sequence Interactionoverview Timing Derivedlanguages SystemsModelingLanguage(SysML) UMLeXchangeFormat(UXF) XMLMetadataInterchange(XMI) ExecutableUML(xUML) Othertopics GlossaryofUMLterms RationalUnifiedProcess ListofUnifiedModelingLanguagetools ObjectModelinginColor Retrievedfrom"https://en.wikipedia.org/w/index.php?title=Class_diagram&oldid=1100929279" Categories:UnifiedModelingLanguagediagramsHiddencategories:ArticleswithshortdescriptionShortdescriptionmatchesWikidataArticlesneedingadditionalreferencesfromFebruary2009AllarticlesneedingadditionalreferencesCommonslinkfromWikidata Navigationmenu Personaltools NotloggedinTalkContributionsCreateaccountLogin Namespaces ArticleTalk English Views ReadEditViewhistory More Search Navigation MainpageContentsCurrenteventsRandomarticleAboutWikipediaContactusDonate Contribute HelpLearntoeditCommunityportalRecentchangesUploadfile Tools WhatlinkshereRelatedchangesUploadfileSpecialpagesPermanentlinkPageinformationCitethispageWikidataitem Print/export DownloadasPDFPrintableversion Inotherprojects WikimediaCommons Languages العربيةБългарскиCatalàČeštinaDeutschEspañolفارسیFrançais한국어हिन्दीHrvatskiBahasaIndonesiaItalianoעבריתLietuviųMagyar日本語PolskiPortuguêsРусскийShqipSlovenčinaСрпски/srpskiSuomiSvenskaதமிழ்TürkçeУкраїнська中文 Editlinks