Copyright © 2012 Pearson Education, Inc.

UML

Java Software SolutionsFoundations of Program Design

Seventh Edition

John LewisWilliam Loftus

Unified Modeling Language• A graphical language used for designing programs

– http://www.uml.org

• UML for short• Used for illustrating the relationships that exist

among classes in a program• There are several kinds of UML diagrams

– Class diagrams– Object diagrams– Collaboration diagrams– Sequence diagrams

Class Diagrams• Use a box to represent a class• Use lines between the classes to represent the

relationships between them• The box representing a class is divided into up to

three sections– The name of the class goes in the top– The instance variables are listed in the middle section– The methods are listed in the bottom section

• Member visibility represented by a symbol+ for public- for private- # for protected

Example Class Diagram

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Dependency• A dependency exists when one class relies on

another in some way, usually by invoking the methods of the other

• We say the dependent class uses the class it depends on

• A driver class (main class) always uses other classes

• Use a dashed arrow to represent the uses relationship

– Arrow points to the class being used

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Class Diagram for Pig Latin

PigLatin

+ main (args : String[]) : void

+ translate (sentence : String) : String- translateWord (word : String) : String- beginsWithVowel (word : String) : boolean- beginsWithBlend (word : String) : boolean

PigLatinTranslator

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Aggregation

• An aggregate is an object that is made up of other objects

– An aggregate object contains references to other objects as instance data

• Therefore aggregation is a has-a relationship

• This is a special kind of dependency; the aggregate relies on the objects that compose it

• Use a solid line with an open diamond to represent has-a

– Diamond is next to the containing classCopyright © 2012 Pearson Education, Inc.

Aggregation in UML

StudentBody

+ main (args : String[]) : void

+ toString() : String

Student- firstName : String- lastName : String- homeAddress : Address- schoolAddress : Address

+ toString() : String

- streetAddress : String- city : String- state : String- zipCode : long

Address

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Inheritance

• Inheritance relationships are shown in a UML class diagram using a solid arrow with an unfilled triangular arrowhead pointing to the parent class

Vehicle

Car

• Proper inheritance creates an is-a relationship, meaning the child is a more specific version of the parent

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Abstract classes

• Use abstract for the stereotype to show a class is abstract

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Class Diagram for Words

Book

# pages : int

+ pageMessage() : void

Dictionary

- definitions : int

+ definitionMessage() : void

Words

+ main (args : String[]) : void

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Class Hierarchies

• Sometimes we only want to show a class hierarchy– Leave out most of the detail

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Interfaces

• Implementing an interface also creates an is-a relationship

• Use a dashed arrow with an outlined triangular head

• Use interface for the stereotype

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CS 225 14

UML Symbols

Symbol Visibility

+ public

- private

# protected

~ package

Relationship Connector

inheritance (is-a)

open arrow

association (uses)

solid line

aggregation/composition(has-a)

open/ soliddiamond

inner class circle with cross

Object Diagrams• These diagrams are used to represent the state of

the program at some time while it is running– The state changes as the program runs

• Represent an object with a box– The type of the object is underlined– The box contains other boxes to hold the instance data

Copyright © 2012 Pearson Education, Inc.

Object diagram

• An object is also represented as a box

• The name of the object (optional) and the name of the class are underlined

• Attribute values may be shown

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Object Diagrams• There are several kinds of diagrams that show the

objects in a program and how they interact– Object diagrams show the state of the objects at a

particular point in the program– Collaboration diagrams show the interactions between

objects by showing method calls– Sequence diagrams show interactions between objects

as a function of time

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Object Diagram

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Collaboration Diagram

• Shows interactions (e.g. method calls) between objects

• Active object is bold

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Sequence Diagram

• Show interactions between objects as a function of time

• Time axis goes down

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Spring 2011

CS 225 21

Tools for UML Diagrams• On onyx

– dia– umbrello– violet

• There are also Eclipse plug-ins but they are usually not open-source– Some of these can build code from the UML diagram