© M.E. Fayad 2000 -- 2005 SJSU -- CmpE L3-5d-S1 Class Diagrams

Software System Engineering

Dr. M.E. Fayad, Professor

Computer Engineering Department, Room #283I

College of Engineering

San José State University

One Washington Square

San José, CA 95192-0180

http://www.engr.sjsu.edu/~fayad

© M.E. Fayad 2000 -- 2005 SJSU – CmpE --- M.E. Fayad L3-5d-S2 Class Diagrams

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Lesson 17:Class Diagrams

© M.E. Fayad 2000 -- 2005 SJSU – CmpE --- M.E. Fayad L3-5d-S3 Class Diagrams

Lesson Objectives

Objectives

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Understand How to put together a class diagram Explore sample of classes and relationships Explore classes and association’s notation Understand the guidelines for putting together a class diagram

© M.E. Fayad 2000 -- 2005 SJSU – CmpE --- M.E. Fayad L3-5d-S4 Class Diagrams

The most common diagram found in

modeling object-oriented system

Model the static design view of a system

The foundation for

– component diagrams

– deployment diagrams

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Class Diagrams (1)

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Class diagrams commonly contain the

following– classes

– interfaces

– collaborations

– dependency, generalization, and association relationship

– notes and constraints 5

Class Diagrams (2)

© M.E. Fayad 2000 -- 2005 SJSU – CmpE --- M.E. Fayad L3-5d-S6 Class Diagrams

Captures the vocabulary of a system

Built and refined throughout development

Purpose– To model the vocabulary of a system

– To model simple collaborations

– To model a logical database scheme

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Class Diagram

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Symbols for Class And Association

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Class and Association’s Notation

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Class Diagram: Example (1)

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Class Diagram: Example (2)

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Class Diagram: Example (3)

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Class Diagram: Example (4)

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Class Diagram: Example (5)

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Class Diagram: Example (6)

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Class Diagram: Example (7)

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Class Diagram: Example (8)

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A well-structured class diagram– is focused on communicating one aspect of a

system’s static design view

– contains only elements that are essential to understanding that aspect

– provides detail consistent with its level of abstraction

– is not so minimalist that it misinforms the reader about important semantics

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Guidelines

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T/F

1. Multiplicity defines how many instances of one class can be associated with the instance of the other class.

2. Bi-directional - The fact that associations are read in both directions

3. For one to one there are three possibilities: A 0..1 0..1 B A 0..1 1..1 B A 1..1 1..1 B

4. Multiplicity is the number of associations of instances of each class.

5. Class diagrams model the dynamic design view of a system. 18

Discussion Questions