II UML Class Diagram & Object Diagram II, Jan Pettersen Nytun, - - PowerPoint PPT Presentation

UML Class & Object Diagram

II

UML Class Diagram & Object Diagram II, Jan Pettersen Nytun, page no 1

Dependency:

A relationship between two modeling elements indicates that a change in the destination may effect the source.

Employee Company

add(e : Employee)

The operation add has an employee object as argument: A change in Employee may inflict a change of the add operation.

Example – dependency between classes: Company is dependent on Employee

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Dependency on Package Diagram

From MagicDraw

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Point

• x : int
• y : int

+ getX() : int + setX(aX : int) : void + getY() : int + setY(aY : int) : void

Class: Describes a Set of Objects

Additional compartments may be supplied, e.g., a constraints compartment.

Modelling tool: Rational Rose 2000

class name

attributes compartment

• perations

compartment visibility

• peration

signature

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Attribute/Property

(Implemented as Field in Java, data member in C++)

Description of a named slot of a specified type in a class. Each object of the class separately holds a value of the type.

<<stereotype>>opt / optvisibilityopt name multiplicityopt : typeopt …

E.g. <<unique>>

• (private) only the class can see

this attribute # (protected) only the class and all of its subclasses + (public) all classes that can see the class can also see the attribute ~ (package) only classes in the package can see the attribute Used if the value of the attribute can be derived from other information.

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Attribute continues

… name multiplicityopt : typeopt = initial-valueopt {property-string}opt

Example: Tagged value e.g. Author = Kari

Example: email[1..*] : String Indicating one or more email addresses. (If no email is present you will still have the empty string (””).) If email[0..*] : String is specified, then email can be null.

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Ordinary Assocaition With Navigability:

If you have a Quiz-object, the associated Question-

• bjects can be directly reach from the Quiz-object.

I.e., there will be a reference to each Question-object inside the Quiz-object but not the other way around.

class Quiz{ // A list of questions Question [] questions; .... } class Question { // no reference to Quiz .... }

Quiz Question * 1..* One possible mapping to Java

association with navigation base class

questions

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A Class Diagram - Mapping to Java

• name : String
• description : String

#name : String #imail : String #homePage : String

Student Course

1

*

responsible for

Person

1

*

• tech. responsible for

1 1

StudentCourseProfile

• finished : boolean

*

*

public class Person { protected String name; protected String imail; protected String homePage; // // Navigation protected Course[] responsibleFor; protected Course[] techResponsibleFor; } public class Student extends Person { // // Navigation public StudentCourseProfile[] studentCourseProfile; }

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Generalization:

A relationship between a more general element and a more specific one. For example: A bird is also an animal.

(Generalization is not an association, but it do relate objects in regard to classification.) Animal Bird

A bird is a specialization of an animal. It inherits the structure and behaviour of Animal. Generalization is a transitive relation!

Eagle

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Realization:

UML: ”A semantic relationships between classifiers, in which one classifier specifies a contract that another classifier guarantees to carry out”.

<<interface>>

Movable

move(x,y)

Snake

move(x,y)

The class Snake realises (implements) the interface Movable. Snake inherits the behaviour specified by the operations of Movable (as an interface Movable has no internal structure).

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Class Diagrams Defines Graph Structures

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Association

• Describes a set of links between objects,

indicating some sort of connection between

• bjects of the involved classes.
• Example: A person may have friends.

Person

friendship f1 f2 * *

p1:Person p2:Person p3:Person p4:Person

:friendship :friendship :friendship :friendship :friendship

possible graph structure, i.e., objects with links

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Person

friendship f1 f2 * *

defines an infinite set of graphs where the nodes are called Person and the edges are called friendship Node

edge end1 end2 * *

“ordinary graph” with “ordinary names” What if we need to attach some information to the edges?

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Different Types Associations

In UML class diagrams you can distinguish between:

– Ordinary Association – Aggregation

(weak aggregation/shared association)

– Composition

(strong aggregation)

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Aggregation/Composition

• Indicates that one object contains objects of a given type,

i.e., a whole/part relationship.

• No cycles are allowed.
• A transitive relation.

Company Department 1 1..*

Composition aggregation (strong aggregation)

Company Department * 1..*

aggregation using aggregation allows a department to be shared among companies Must be 1 or 0..1 No limitations on this multiplicity the whole the part

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Aggregation is a weaker form of aggregation than composition. A part instance might be included in more than one aggregation at a time, which is not allowed for composition.

Company Department 1 1..* Employee * 1..*

a department can only belong to one company at a time an employee can belong to several departments at a time

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• Composition defines a directed tree and an

aggregation defines a directed graph (without cycles).

• Using these properties to define a directed graph and

directed tree:

Node

child * root 0..1

DirectedTree

0..1 0..1

Node

* *

DirectedAcyclicGraph

0..1 * edge edge predecessor successor topRoot

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:Node :Node :Node :Node :Node :Directed- AcyclicGraph :Node :Node :Node

Do you see errors?

Node

* *

DirectedAcyclicGraph

0..1 * edge predecessor successor

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:Node :Node :Node :Node :Node :Directed- AcyclickGraph :Node :Node :Node

Do you see errors?

Node

* *

DirectedAcyclicGraph

0..1 * edge predecessor successor

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:Node :Node :Node :Node :Node :DirectedTree :Node :Node :Node

Do you see errors?

Node

child * root 0..1

DirectedTree

0..1 0..1 edge topRoot

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:Node :Node :Node :Node :Node :DirectedTree :Node :Node :Node

Do you see errors?

Node

child * root 1

DirectedTree

0..1 0..1 edge topRoot

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UML 2.1 specification: “… If a composite is deleted, all of its parts are normally deleted with it… deleting an element in

• ne part of the graph will also result in the deletion
• f all elements of the subgraph below that element.”

Deletion Characteristics

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