1. Chapter 3,Class Diagram

2. Outline of this Class Activity diagrams Class diagrams
Describe the dynamic behavior of a system, in particular the workflow.
Class diagrams
Describe the static structure of the system: Objects, attributes, associations
Use case diagrams
Describe the functional behavior of the system as seen by the user
Sequence diagrams
Describe the dynamic behavior between objects of the system
Statechart diagrams
Describe the dynamic behavior of an individual object

3. Class Diagrams Class diagrams represent the structure of the system
Used
during requirements analysis to model application domain concepts
during system design to model subsystems
during object design to specify the detailed behavior and attributes of classes.
Table zone2price
Enumeration getZones()
Price getPrice(Zone)
TarifSchedule *
Trip
zone:Zone
Price: Price

4. Classes Type Name Signature Attributes Operations
Table zone2price
Enumeration getZones()
Price getPrice(Zone)
TarifSchedule
zone2price
getZones()
getPrice()
TarifSchedule
Name
Attributes
Operations
Signature
TarifSchedule
A class represents a concept.
A class encapsulates state (attributes) and behavior (operations):
Each attribute has a type
Each operation has a signature
The class name is the only mandatory information

5. Instances An instance represents a phenomenon.
zone2price = {
{‘1’, 0.20}, {‘2’, 0.40},
{‘3’, 0.60}}
tarif2006:TarifSchedule
zone2price = {
{‘1’, 0.20}, {‘2’, 0.40},
{‘3’, 0.60}}
:TarifSchedule
An instance represents a phenomenon.
The attributes are represented with their values.
The name of an instance is underlined.
The name can contain only the class name (TarifSchedule) of the instance (anonymous instance).

6. Actor vs Class vs Object
An entity outside the system to be modeled, interacting with the system (“Passenger”)
Class
An abstraction modeling an entity in the application or solution domain
The class is part of the system model (“User”, “Ticket distributor”, “Server”)
Object
A specific instance of a class (“Joe, the passenger who is purchasing a ticket from the ticket distributor”).

7. Associations * Associations denote relationships between classes.
Price Zone
Enumeration getZones()
Price getPrice(Zone)
TarifSchedule
TripLeg *
Associations denote relationships between classes.
The multiplicity of an association end denotes how many objects the instance of a class can legitimately reference.

8. 1-to-1 and 1-to-many Associations
Country
name:String
City 1
1-to-1 association
Polygon
draw()
Point
x: Integer
y: Integer *
1-to-many association

9. Many-to-Many Associations
Company * *
StockExchange
tickerSymbol

10. Aggregation
An aggregation is a special case of association denoting a “consists-of / part-of / has-a” hierarchy.
The aggregate is the parent class, the components are the children classes.
Exhaust system
Muffler
diameter
Tailpipe 1
0..2
A solid diamond denotes composition (“contains-a”): A strong form of aggregation where the life time of the component instances is controlled by the aggregate. That is, the parts don’t exist on their won (“the whole controls/destroys the parts”).
TicketMachine
ZoneButton 3

11. Difference of Aggregation and Composition
Bir örnek Arabadır. Araba Parçalarından oluşur. Bu parçalara sahiptir. Eğer bir Parça yoksa araba bozuktur. Araba Parçalarıyla Composition oluşturur.
Ayrıca Arabanın Yolcuları vardır. Yolcular Arabanın Parçası değildir. Eğer bir Yolcu yoksa Araba bozuk değildir. Araba Yolcularına sahip değildir. Arabada değillerse başka bir yerdedirler. İlişki geçicidir. Yolcular gelir ve gider. Araba ve Yolcular arasında Aggregation ilişkisi vardır.
Her iki ilişki aslında Composition’dır. Arabanın hem Parçaları hem de Yolcuları vardır. Farklılık süresindedir. Parçalarla olan ilişki daimidir, Yolcularla olan ilişki geçicidir.

12. Without qualification
Qualifiers
Directory
File
filename
Without qualification 1 *
With qualification
Directory
File 1
filename
0..1
Qualification: A technique for reducing the multiplicity of associations by replacing many-to-many or one-to-many associations qith qualified associations.
Qualified association: An association in which one end is indexed by an attribute.
Qualifiers can be used to reduce the multiplicity of an association.

13. Qualification: Another Example
Company *
Lists *
StockExchange
tickerSymbol *
StockExchange
Company
Lists 1
tickerSymbol

14. Inheritance
Button
ZoneButton
CancelButton
Inheritance is another special case of an association denoting a “kind-of” hierarchy.
Inheritance simplifies the analysis model by introducing a taxonomy.
The children classes inherit the attributes and operations of the parent class.

15. Packages Account Bank Customer
Packages help you to organize UML models to increase their readability.
Pretty much all UML elements can be grouped into packages. Thus, classes, objects, use cases, components, nodes, node instances etc. Can all be organized as packages.
We can use the UML package mechanism to organize classes into subsystems
Any complex system can be decomposed into subsystems, where each subsystem is modeled as a package.
Account
Bank
Customer

16. Object Modeling in Practice
Foo
Amount
CustomerId
Deposit()
Withdraw()
GetBalance()
Class Identification: Name of Class, Attributes and Methods
Is Foo the right name?

17. Object Modeling in Practice: Brainstorming
“Dada”
Amount
CustomerId
Deposit()
Withdraw()
GetBalance()
Foo
Amount
CustomerId
Deposit()
Withdraw()
GetBalance()
Account
Amount
CustomerId
Deposit()
Withdraw()
GetBalance()
Naming is important!
Is Foo the right name?

18. Object Modeling in Practice: More classes
Account
Amount
Deposit()
Withdraw()
GetBalance()
Customer
Name
Bank
Name
CustomerId
AccountId
CustomerId
1) Find New Classes
2) Review Names, Attributes and Methods

19. Object Modeling in Practice: Associations
Account
Amount
Deposit()
Withdraw()
GetBalance()
Customer
Name
CustomerId
AccountId
Bank ? * *
owns
has 2
1) Find New Classes
İçi dolu baklava: Composition. “Contains-a” ilişkisi.
İçi boş baklava: Aggregation “has-a” ilişkisi.
2) Review Names, Attributes and Methods
3) Find Associations between Classes
4) Label the generic assocations
5) Determine the multiplicity of the assocations
6) Review associations

20. Practice Object Modeling: Find Taxonomies
Account
Amount
Deposit()
Withdraw()
GetBalance()
CustomerId
AccountId
Bank
Name *
Customer
Name
CustomerId()
Has *
Savings
Account
Withdraw()
Checking
Account
Withdraw()
Mortgage
Account
Withdraw()
İçi dolu baklava: Composition. “Contains-a” ilişkisi.
İçi boş baklava: Aggregation “has-a” ilişkisi.
Taxonomy: Hiyerarşi yaratıp, sınıflandırma yapmak.
Üçgenler: Inheritance. “Kind-of” ilişkisi.

21. Practice Object Modeling: Simplify, Organize
Account
Amount
Deposit()
Withdraw()
GetBalance()
CustomerId
AccountId
Show Taxonomies
separately
Savings
Account
Checking
Account
Mortgage
Account
İçi dolu baklava: Composition. “Contains-a” ilişkisi.
İçi boş baklava: Aggregation “has-a” ilişkisi.
Taxonomy: Hiyerarşi yaratıp, sınıflandırma yapmak.
Üçgenler: Inheritance. “Kind-of” ilişkisi.
Withdraw()
Withdraw()
Withdraw()

22. Practice Object Modeling: Simplify, Organize
Customer
Name
CustomerId()
Account
Amount
Deposit()
Withdraw()
GetBalance()
CustomerId
AccountId
Bank
Has *
Use the 7+-2 heuristics
or better 5+-2!
İçi dolu baklava: Composition. “Contains-a” ilişkisi.
İçi boş baklava: Aggregation “has-a” ilişkisi.
Taxonomy: Hiyerarşi yaratıp, sınıflandırma yapmak.
Üçgenler: Inheritance. “Kind-of” ilişkisi.

23. Practical Tips - 1 Simplicity Diagram layout Names References
To be easier to understand/takes less effort
Try to use minimal number of classes
Diagram layout
Draw diagrams in symmetric manner
Try to avoid crossing lines
Names
Descriptive, crisp, unambiguous
Singular nouns for the name of classes
References
Do not bury object references inside objects
Model these as association

24. Practical Tips - 2 Generalization Association end names
Do not nest subclasses too deeply
Two or three levels deep is good
Association end names
To unify references to the same class
Be alert for multiple uses of the same class
Qualified associations
To improve the precision of an association
Challenge with a multiplicity of “many”
Review
Try to get others to review model
Clarify names, improve abstraction, add info
Documentation
Diagram cannot describe the rationale
Always document models

25. Review of Class Diagrams
Multiplicity
Inheritance
Association End Name (Role)
Class
Aggregation
Class diagrams represent the structure of the system

26. Class Diagram Examples - 1
- Çift taraflı bir bağıntı örneği -

27. Class Diagram Examples - 2

28. Class Diagram Examples - 3

29. Class Diagram Examples - 4

30. Class Diagram Examples - 5

31. Another view on UML Diagrams