CS 3500

L03A - 1

What is UML?

A modeling language standardized by the OMG (Object Management Group), and widely used in OO analysis and design

– A modeling language is a visual language for representing software blueprints

– Latest version is 2.0

UML provides a standard notation, semantics for a set of OO abstractions

CS 3500

L03A - 2

UML Overview

UML defines a visual representation of a concept Everything that is defined in this has meaning

– Just like when writing code, you use () or , or + to represent something

– Same is true in UML

So, be careful of the types of arrows, boxes, etc. that you use

Be careful of where you put other symbols Remember that there is a REAL syntax defined for

UML– You can’t just write/draw whatever you like

Our focus – reading UML Class diagrams – Next semester, writing them and other diagrams

CS 3500

L03A - 3

+name()+method1(:double):double+method2():bool+classMethod()

-x: double-y: double-z: double-n: int

name

UML ClassClass name

Data members(attributes)

Instance methods

Arguments

Return typesClass method (static)

These compartments are optional. But if you need methods, then you have to have at least empty data member compartment.

Important – if something isn’t specified, then that doesn’t necessarily mean that it isn’t there. For example, does name take an argument or not, does it return a value?

CS 3500

L03A - 4

+Name()+Name(:Name)+operation()+classMethod

-instanceDataMember: type-classDataMember: type

Name

Class Attributes

Attributes are the instanceand class data members

Class data members (underlined) are shared between all instances(objects) of a given class (think static).

Data types shown after ":"

Visibility shown as+ public- private# protected

Attributecompartment

Attribute Modelvisibility name : type multiplicity = default {property-string}

CS 3500

L03A - 5

+Name()+Name(:Name)+operation()+classMethod

-instanceDataMember: type-classDataMember: type

Name

Class Operations

Operations are the classmethods with their argumentand return types

Public (+) operations define theclass interface

Class methods (underlined) have only access to class datamembers, no need for a classinstance (object)

Parameter List –direction name: type = defaultDirection Model –direction – in, out, inout

Operationscompartment

Operations Modelvisibility name (parameter-list) : return-type {property-string}

CS 3500

L03A - 6

Multiplicity - 1

Indicates how many objects may fill the property– 1 – exactly one

– 0 .. 1 – may or may not have one

– * – zero or more

– n .. m – from n to m where n < m

Default is [1]– But it is best to not use default even if value is 1 to make it clear

Question – if you indicate that something is a n..m multiplicity, then how is this realized?

CS 3500

L03A - 7

Unary Association

A knows about B, but B knows nothing about A

Arrow shows direction of association in direction ofdependency

+doSomething()

-myB: B

A

+service()

B

Void doSomething() { myB.service();}

+doSomething()

A

+service()

B-myB

1

UML Comment

These twodiagramsare identicalin what theymean.

CS 3500

L03A - 8

Unary Association IS an Attribute

Exactly the same as an attribute– Did you hear me? Exactly the same!!!

Solid line (source to target) Name goes at the target end, plus multiplicity It is WRONG to include both an association and a

attribute of the same thing– That implies that BOTH exist at the same time

What is the difference between a unary association (line) and an attribute?

– IT IS THE SAME THING!!!!! Don’t forget!!!!

CS 3500

L03A - 9

Binary Association

Binary association: both classes know each other

Usually "knows about" means a pointer or referenceOther methods possible: method argument, tables, database, ...Implies dependency cycle

void doSomething() { myB.service();}

+doSomething()

A

+service()+operation()

B-myB-myA

1 1

void operation() { myA.service();}

CS 3500

L03A - 10

Dependency

Weak relationships (also transitory):– Class A simply knows of class B

» E.g., a method in A creates and immediately returns an object of class B

That is: a change in one may force changes in the other although there is no explicit association between them.

A B

CS 3500

L03A - 11

Generalization (Inheritance)

Base class or super class

Derived class or subclass

Arrow shows directionof dependency

+setX(:double)+getX():double

-myX: double

A

+operation()

B

public class B : A { …}

CS 3500

L03A - 12

Aggregation

Aggregation = Association with "whole-part" relationship

Shown by hollow diamondat the "whole" side

No lifetime control implied

+doSomething()

Box

void doSomething() { … aContent.service(); ..}

+service()

ContentaModule

1

CS 3500

L03A - 13

Composition

Composition = Aggregation with lifetime control

Shown by filled diamondat the "owner" side

Lifetime control implied

Lifetime control can betransferred

Lifetime control: construction anddestruction controlled by "owner"→ call constructors and destructors

(or have somebody else do it)

+speed(): double

Car

double speed() { … wheels[1] .. wheels[3] …}

+type

Wheelwheels

4

CS 3500

L03A - 14

Composition/AggregationNotations

MovieTheater BoxOffice

Movie

1 1

0..*

0..*

composition

aggregation

whole

part

part

CS 3500

L03A - 15

Vehicle

+ weight : int+ topSpeed : int+ VIN : string

+ getOwner ( )

Owner

+ firstName : string+ lastName : string+ phoneNumber : string

+ contactOwner ( [in] message : string ) : bool+ getName ( ) : string

- myOwner

10..*

- myVehicles

Car

+ modelType : string+ maxPassengers : int

+ addRepairNote ( [in] note : string ) : bool

Motorcycle

+ modelType : stringWheel

+ maxMileage : int

- wheels

2

- wheels 4

Describe This Diagram