1. Modeling Classes with UML
CSCE 121
J. Michael Moore

2. Modeling Objects Objects used in many programming languages
Ideally is independent of the programming language
Language Agnostic
The focus should be what instead of how.
There are many options, so leave the implementation details to the coder.
Think about what data means or a mathematical definition instead of focusing on the datatypes available in a language.
Dollars instead of double.
Integer instead of int.
Floating point instead of double or float.
Letters instead of char.
List instead of vector. (You can say array if you mean it in the mathematical sense.)

3. Class Start thinking about what you want to represent Characteristics
Candidates for attributes
Actions (by / to object)
Candidates for methods

4. UML Unified Modeling Language Used primarily for Software Engineering
Language Agnostic
Many types of UML diagrams used for design and modeling
Class diagrams
Structure diagrams
Sequence diagrams
Activity diagrams
State machine diagrams

5. Methods / Member Functions
UML Class Diagram
Model Classes (language agnostic of course!)
3 parts
Include what we need, not everything we can think of.
Programs can help
Visio: Free on Dreamspark
(Collaborative)
Any program you can draw boxes and type text!
Name
Attributes /
Data Members
Methods / Member Functions

6. Attributes Book <AttributeName>: <AttributeType>
Attribute Type is optional
Start with lowercase
Type after colon
Types are NOT C++ datatypes!
Should be descriptive of what it is, not how it will be stored in C++
Ex: Dollars instead of double
Can include this type of information for methods too
Book
title
author: String
due: Date
checkedOutBy: Patron

7. Methods
<MethodName>(<parameter>: <AttributeType>):<ReturnType>
Start with lowercase
Book
title: String
author: String
due: Date
checkOut(patron: Patron, due: Date)
getAuthor(): String
setTitle(title: String)

8. Visibility Book Public: prepend name with ‘+’
Private: prepend name with ‘-’
Book
-title
-author: String
-due: Date
+checkOut(patron: Patron, due: Date)
+getAuthor(): String
+setTitle(title: String)

9. Relationships Show relationship between classes Association Person
Has a
Aggregation
Has an aggregation (grouping) of
Composition
Like has a, but is a part of
More later…
Person
Umbrella
Class Roster
Student
Person
Arm

10. Try to match relation to attribute/method or to the name.
Relationships
Library
-name: String
-collection: Book
Book
+addBook(book: Book)
-title: String
-author: String
-due: Date
-checkOutBy: Patron
Patron
+checkOut(patron: Patron, due: Date)
+getAuthor(): String
+setTitle(title: String)
Try to match relation to attribute/method or to the name.
-name: String