class diagram.pptx

8/17/2019 Class Diagram.pptx

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Class Diagram

SwapnilSoner


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Class Diagram

• A class diagram is a schema, patternor templates for describing manypossible instances of data.

• Describes classes.


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Instance diagram

• Describes how a particular set ofobjects relate to each other.

• Describes objects


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erson

Class Diagram

!erson"#am

!erson" $ai

Instance Diagram


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Attribute

• An attribute is a data value held bythe objects in a class.

• &ach attribute name is uni'ue withina class.

• An attribute should be a pure data(alue, not an object.


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*bject +odeling otations

erson

name- stringage- integer

Class withAttributes

!erson"#am

4

!erson" $ai34

*bjects with /alues


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*perations and +ethods

• An operation is a function ortransformation that may be applied toor by objects in a class.

•

All objects in a class share the sameoperations.

• 1he same operation may apply to manydi2erent classes.

•A method is the implementation of anoperation for a class.


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erson

nameage

changejob

changeadd

erson

nameage

changejob

changeadd

erson

nameage

print

5ile

namesi6e

*perations


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Association

• associations are the means forestablishing relationships among objectsand classes.

•

Associations are bidirectional.• In real, both directions of tra(ersal are

e'ually meaningful and refer to sameassociation.

• Associations are often implemented inprogramming languages as pointers fromone object to another.

•

A pointer is an attribute in one object thatcontains an e8 licit reference to another


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Countryname

Cityname

;ascapital

!Country"India

!City"Delhi

;ascapital

;ascapital

ClassDiagram

Instance Diagram

*neto*ne Association andlin


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+ultiplicity

• It speci=es how many instances ofone class may relate to a singleinstance of an associated class.

• +ultiplicity depends uponassumptions and how you de=ne theboundaries of a problem.


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#ole ames

• A role is one end of an association.

• A binary association has roles, each ofwhich may ha(e a role name.

•

A role name is a name that uni'uelyidenti=es one end of an association.

• #oles often appear as nouns in problemdescriptions.

• >se of role name is optional.• #ole names are necessary for associations

between two objects of the same class.


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person companyemployee employer

?or


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ordering

• If order of objects re'uired

• Indicated by writing @orderedBne8t to multiplicity dot for the role.

window screenorderedB

/isibleon

*rdered sets in an association


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uali=cation

• It relates two classes and a 'uali=er.

• uali=er is a special attribute that reducesthe e2ecti(e multiplicity of an association.

•

*netomany or manytomany may be'uali=ed that can be reduced to onetoone. ! but not always"

• It distinguishes among the set of objects at

the many end of an association.• A qualifed association can also be

considered a orm o ternary association.


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Directory

5ile5ile name

A 'uali=ed association

A directory plus a =le name yields a =le


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Aggregation

• It is a partof relationship

• Aggregation is a special form ofassociation.


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document paragraph sentence

Aggregation


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&S& E +odeling *bjects and Classes

/isibility and Scope of 5eatures

Don’t worryaboutvisibility tooearly!

Don’t worryaboutvisibility tooearly!

class diagram.pptx

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