Презентация на тему «UML and Classes, Objects and Relationships»

UML and Classes, Objects and Relationships [2]

Defining Domain Models Using Class Diagrams

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Agenda

Class Relationships and UML Notations Association - DONE Generalization Realization Dependency Class Diagram Object Diagram Summary

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Association - Multiplicity

Student

Course

A Student can take many Courses and many Students can be enrolled in one Course.

takes

*

*

254: Course

Alice: Student

253: Course

Jill: Student

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Notes

One class can be relate to another in a One-to-one One-to-many One-to-one or more One-to-zero or one One-to-a bounded interval (one-to-two through twenty) One-to-exactly n One-to-a set of choices (one-to-five or eight)

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Notes

Multiplicity can be expressed as, Exactly one - 1 Zero or one - 0..1 Many - 0..* or * One or more - 1..* Exact Number - e.g. 3..4 or 6 Or a complex relationship – e.g. 0..1, 3..4, 6..* would mean any number of objects other than 2 or 5

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Association - Self

An association that connects a class to itself is called a self association.

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Association - Self

Employee

A Company has Employees. A single manager is responsible for up to 10 workers.

manager

Responsible for

worker

1

0..10

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Association - Multiplicity

Team

Player

A cricket team has 11 players. One of them is the captain. A player can play only for one Team. The captain leads the team members.

member of

1

11

Captain

Team Member

1

0..1

10

Captain

1

Leads

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Class Relationships

Association Generalization Realization Dependency

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Generalization (Inheritance)

Child class is a special case of the parent class

SuperClass

SubClass1

SubClass2

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Generalization (Inheritance) e.g

Circle

GraphicCircle

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Inheritance - Implementation

public class Circle { } public class GraphicCircle extends Circle { }

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Abstract Class

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Abstract Methods (Operations)

Shape

Circle

Rectangle

draw()

draw()

draw()

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Abstract class and method Implementation

public abstract class Shape { public abstract draw(); //declare without implementation ……… } public class Circle { public draw(){ ……. } ….. }

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Class Relationships

Association Generalization Realization Dependency

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Realization- Interface

Interface is a set of operation the class carries out

OR

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Realization - Implementation

public interface TypeWriter { void keyStroke() } public class KeyBoard implements TypeWriter { public void keyStroke(){ ……… } }

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Class Relationships

Association Generalization Realization Dependency

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Dependency

Change in specification of one class can change the other class. This can happen when one class is using another class.

Circle

Point

Move(p:Point)

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Dependency cont

Dependency relationship can be used to show relationships between classes and objects.

circleA:Circle

Circle

circleB:Circle

<<instanceOf>>

<<instanceOf>>

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Class Diagrams

The UML class diagram consists of several Classes, connected with Relationships.

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Class Diagram - Example

Draw a class diagram for a information modeling system for a school. School has one or more Departments. Department offers one or more Subjects. A particular subject will be offered by only one department. Department has instructors and instructors can work for one or more departments. Student can enrol in upto 5 subjects in a School. Instructors can teach upto 3 subjects. The same subject can be taught by different instructors. Students can be enrolled in more than one school.

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Class Diagram - Example

School has one or more Departments.

Department offers one or more Subjects. A particular subject will be offered by only one department.

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Class Diagram - Example

Department has Instructors and instructors can work for one or more departments.

Student can enrol in upto 5 Subjects.

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Class Diagram - Example

Instructors can teach up to 3 subjects. The same subject can be taught by different instructors.

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Class Diagram - Example

Students can be enrolled in more than one school.

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Class Diagram Example

1…*

has

1

offeres

assignedTo

member

1..*

attends

teaches

1

1..*

1..*

1..*

*

*

1..5

1..*

1..3

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Object Diagram

Object Diagram shows the relationship between objects. Unlike classes objects have a state.

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Object Diagram - Example

c1: Company

d1: Department

d2: Department

name=“Sales”

name=”CSSE”

manager

employee

p2: Person

p1: Persont

name=“Raj”

name=“Rao”

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Summary

We have discussed the following concepts and UML notations related: Association Generalization Realization Dependency How to create a Class Diagram that contains all the above relationships Object Diagram for Uni.Dept.system.

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