© 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 1 Advanced UML Class Diagrams.
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Transcript of © 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley 1 Advanced UML Class Diagrams.
1© 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley
Advanced UML Class Advanced UML Class DiagramsDiagrams
2© 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley
ObjectivesObjectives
To present the portions of the UML class diagram notation not already covered
To present examples to illustrate the use of the notation
To present heuristics for using the notation well
3© 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley
TopicsTopics
Generalization Abstract and concrete operations and classes Interfaces Feature visibility Class and instance variables and operations Aggregation and composition Association classes and qualifiers Other association adornments More class diagram heuristics
4© 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley
GeneralizationGeneralization
Generalization is the UML relation that holds between one model element (the parent) and another (the child) when the child is a special type of the parent.
• Represented by a hollow rectangle and lines
• Rectangle attaches to the parent and lines to the children
Generalization is used in UML class diagrams to model inheritance.
5© 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley
Generalization ExampleGeneralization Example
Mammal
PumaTiger
Feline
Quadruped
Lion
Lizard
6© 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley
Generalization versus Generalization versus AssociationAssociation
Generalization is a relation between classes.
Associations represent relations on sets of class instances designated by the associated classes.
Generalization is not a kind of association. They
• Never have multiplicities,• Never have rolenames,• Never have names (they already have a
name: generalization).
7© 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley
Abstract Operations and Abstract Operations and ClassesClasses
An abstract operation is an operation without a body; a concrete operation has a body.
An abstract class is a class that cannot be instantiated; a concrete class can be instantiated.
A class • Must be abstract if it has an abstract
operation;• May be abstract even if it has no abstract
operations.
8© 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley
Using and Representing Using and Representing Abstract Classes and Abstract Classes and OperationsOperations
Abstract classes force their subclasses to implement certain operations.
Abstract classes are represented in UML by
• Italicizing their names,• Stereotyping them «abstract» or• Giving them an {abstract} property.
Abstract operations are represented in UML by
• Italicizing their specification or• Giving them an {abstract} property.
9© 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley
Abstract Class and Abstract Class and Operation ExamplesOperation Examples
Circle ScreenRenderer Book
Document{ abstract }
callNumberdescriptors : String[*]render()
Renderer«abstract»
Shape
areaOf() : float { abstract }
10© 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley
InterfacesInterfaces
A UML interface is named collection of public attributes and abstract operations.
• Provided interfaces—realized by a class or component and represented by A ball (lollipop) symbol or A stereotyped class icon with a realization
connector
• Required interfaces—needed by a class or component and represented by A socket symbol or A dependency arrow to a ball symbol or A dependency arrow to a stereotyped class icon
11© 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley
Provided Interface Provided Interface NotationsNotations
TimerObserver
Observer
TimerObserver
«interface»Observer
update( arg : Object )
12© 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley
Required Interface Required Interface NotationsNotations
Observer
TimerObserver
«interface»Observer
update( arg : Object )
TimerTimer
Observer
Timer
13© 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley
Module Assembly Module Assembly NotationsNotations
«interface»Observer
update( arg : Object )
Timer
Observer
Timer
TimerObserverTimerObserver
14© 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley
UML Feature VisibilityUML Feature Visibility
Public—Visible anywhere that the class in which it appears is visible; denoted by +.
Package—Visible anywhere in the package containing the class in which it appears; denoted by ~.
Protected—Visible in the class in which it appears and all its sub-classes; denoted by #.
Private—Visible only in the class in which it appears; denoted by -.
15© 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley
Feature Visibility Feature Visibility ExampleExample
Alarm
+ identifier : String {constant}# location : String# description : String- classification : Classifier
+ getLocation() : String+ getDescription() : String+ action()~ setClassification( c : Classifier)~ getClassification() : Classifier# basicAction()
FireAlarm IntrusionAlarm FloodAlarm
16© 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley
Class and Instance Class and Instance Variables and Variables and OperationsOperations
An instance variable is an attribute whose value is stored by each instance of a class.
A class variable is an attribute whose value is stored only once and shared by all instances.
An instance operation must be called through an instance.
A class operation may be called through the class.
In UML class variables and operations are called static.
• Indicated by underlining an attribute’s or operation’s specification
17© 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley
Attribute and Operation Attribute and Operation Specification ExamplesSpecification Examples
Tokenizer
+ token : TokenType = NONE+ tokenText : String- buffer : String- bufferPosition : integer- delimiters : String
- theInstance : Tokenizer
+ getInstance() : Tokenizer+ nextToken()+ setBuffer( buffer : String )+ setDelimiter( delim : String )
TokenType
+ NONE : TokenType { constant }+ NUMBER : TokenType { constant }+ IDENTIFIER : TokenType { constant }+ EQUAL : TokenType { constant }+ MINUS : TokenType { constant }+ PLUS : TokenType { constant }- name : String
- TokenType( name : String )+ toString() : String
18© 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley
Aggregation and Aggregation and CompositionComposition
The aggregation association represents the part-whole relation between classes.
• Denoted by a solid diamond and lines• Diamond attaches to the aggregate (whole)
while lines attach to the parts• May have all association adornments
The composition association is an aggregation association in which each part can be related to only one whole at a time.
• Denoted by a hollow diamond and lines
19© 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley
Aggregation and Aggregation and Composition ExamplesComposition Examples
Human
FamilyChurch
Person
FootHand
LegArm
0..2 0..2
0..1 0..1
*
1..*
1..*
1..*
20© 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley
Problems with Problems with AggregationAggregation
Often abused• Must be transitive:
(x)(y)(z)((Rxy • Ryz) Rxz)
• Often used for collection membership, which is not transitive
Aggregation, composition, and collection membership can be represented by plain associations.
21© 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley
Association ClassesAssociation Classes
An association class represents a relation on instances of the classes is connects, and it holds data and behavior.
• Association class connector is a dashed line• Connects class with an association line
There can be only one instance of an association class for each pair of instances of the associated classes.
If more instances are need, interpose a new class (a reified association).
22© 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley
Association Class Association Class ExampleExample
Medication Patient* *
Prescription
- date
23© 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley
Association QualifiersAssociation Qualifiers
An association qualifier is one or more association attributes that, together with instances of the qualified class, pick out instances of an associated target class.
• Represented by a box with association attributes and a line
• Attributes have standard specifications except that no initial values are allowed
• Box is attached to the qualified class• Line runs to the target class• Line can have association adornments
24© 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley
Association Qualifier Association Qualifier ExamplesExamples
Catalog
Course
departmentnumber
List
Object
index:int
0..1 0..1
1..**
25© 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley
Rolename VisibilityRolename Visibility
Associations are often implemented using references.
• Rolename may be a reference attribute name
Rolenames may have visibility modifiers (+, #, ~, -).
Rolename visibility modifiers may be suppressed.
26© 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley
Association NavigabilityAssociation Navigability
An association between classes A and B is navigable from A to B if an instance of A can access an instance of B; otherwise it is non-navigable.
• Navigability is denoted by adding an arrowhead to the association line in the navigation direction
• Non-navigability is denoted by placing an x on the association line in the navigation direction
• Navigability markers can be suppressed, so no markers means the diagram is silent on navigability
27© 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley
Rolename Visibility and Rolename Visibility and Navigability ExampleNavigability Example
Game
Player
Referee
- player1..*
*
0..1 - myGame
1
28© 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley
Class Diagram Class Diagram Heuristics 1Heuristics 1
Never place a name, rolenames, or multiplicities on a generalization connector.
Use the «abstract» stereotype and {abstract} property to indicate abstract classes and operations when drawing diagrams by hand; use italics when drawing diagrams on the computer.
Use the interface ball and socket symbols to abstract interface details and a stereotyped class symbol to show details.
29© 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley
Class Diagram Class Diagram Heuristics 2Heuristics 2
Don’t italicize interface or operation names.
Show provided interfaces with the interface ball symbol or the stereotyped class symbol and a realization connector.
Show required interfaces with the interface socket symbol or dependency arrows to stereotyped class symbols or interface ball symbols.
Avoid aggregation and composition.
30© 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley
Class Diagram Class Diagram Heuristics 3Heuristics 3
If aggregation or composition is used, check that the represented relation is transitive.
Use association classes when only a single association class instance is associated with each pair of instances of the associated classes; otherwise use a reified association.
Determine multiplicities involving a qualifier by considering qualified class instances and particular combinations of qualifier attribute values.
31© 2007 Pearson Education, Inc. Publishing as Pearson Addison-Wesley
SummarySummary
UML class diagrams have great expressive power: they are able to show
• Generalization• Abstract operations and classes• Class and instance variables and operations• Interfaces and interface assemblies• Aggregation and composition associations• Association classes and quantifiers• Feature and rolename visibility• Navigability