1. Object Oriented Methodologies
Lesson06
Jerry Kotuba

2. Agenda Class Diagrams Solution I-C-E-03 & 04 Posted
Take up the Class Diagrams
Class Diagrams
Whole-to-part associations
I-C-E-05
Object Oriented Methodologies
Jerry Kotuba

3. Generalization, Inheritance & Constraints
generalization path
solid line with hollow arrowhead pointing from subclass to superclass
indicate basis of generalization
name the path for the attribute being removed = called the discriminator
discriminator shows which property is abstracted by a generalization relationship
SYST Object Oriented Methodologies
Jerry Kotuba

4. Constraints on Generalization
constraints on the subclasses
overlapping: descendent may be descended from more than one of the subclasses
student can be both a research and teaching assistant
disjoint: descendent may not be descended from more than one of the subclasses
patient can not be both out and resident
SYST Object Oriented Methodologies
Jerry Kotuba

5. Constraints on Generalization
complete: all subclasses are listed
only have out and resident patients
incomplete: all subclasses are not listed
more subclasses are available
can have casual, part-time employees
SYST Object Oriented Methodologies
Jerry Kotuba

6. Whole-to-Part Associations
The UML provides ways to model two types of whole-to- part associations – aggregation and composition.
Object Oriented Methodologies
Jerry Kotuba

7. Definitions
aggregate: In an aggregation, the class representing the whole. aggregation: An association between classes representing a part-to- whole relationship in which the parts and the whole may exist independently and in which a single part may be associated with more than one whole at the same time.
Object Oriented Methodologies
Jerry Kotuba

8. Definitions…cont’d
composite: In a composition, a class representing the whole. composition: An association between classes representing a whole-to- part relationship in which the parts may belong to only one whole at a time and the whole does not exist without its parts.
Object Oriented Methodologies
Jerry Kotuba

9. Example of an Aggregation.
Object Oriented Methodologies
Jerry Kotuba

10. Example of a Composition.
Object Oriented Methodologies
Jerry Kotuba

11. Aggregation and Composition.
Object Oriented Methodologies
Jerry Kotuba

12. Categories of Whole-to-Part Associations
There are three relationships that sometimes occur in an object model:
Assemblies of parts
Members of groups
Containers and their contents
You may find these useful for making your model a better tool for understanding and communication.
The model can always be built without these. They do not really affect its use for system design, just for talking to the users.
Object Oriented Methodologies
Jerry Kotuba

13. Assemblies of parts
Taking something apart into its components is a technique we humans often use to understand how something works.
Often we find it improves our understanding to model
A product and its components
A business consists of branches, departments, etc.
A country consists of states, provinces, counties, boroughs, shires, towns, villages, cities, etc.
Object Oriented Methodologies
Jerry Kotuba

14. Containers and their contents
Container-Contents is a different and less common relationship.
In some situations we may find it helpful to view a relationship as one of these, e.g.,
Truck or Aircraft and the Products or Shipments that it carries
An actual shipping container and the goods it holds
A ship, bus or airplane and its passengers
A building and the businesses it houses.
Object Oriented Methodologies
Jerry Kotuba

15. Assemblies of parts Vs Containers and their contents
A Container, however, is still a perfectly good Container, even without its Contents
The jar is still OK even without the “hunny.”
And the Contents are perfectly OK without the Container
(although the “hunny” might get all over one’s paws!)
The essential difference between these relationships is that:
With Assemblies of parts, if you take the component away, the assembly (whole) probably won’t work any more
Take a wheel off a car
Take a hand off a clock
Take a leg off a table.
Jerry Kotuba
Object Oriented Methodologies

16. Collection-Member (members of groups)
Collection-Member is also a different and relatively uncommon relationship.
Sometimes we meet an actual collection:
A library full of books
An art gallery
A stamp or jewelry collection
A fleet of trucks, ships or aircraft
Other times it may help to use this to describe:
A church, club or regiment and its members
An inventory of furniture or equipment
A herd, mob, flock, school or skein of animals.
Jerry Kotuba
Object Oriented Methodologies

17. Your Turn…
Think about a book, which consists of a cover, table of contents, chapters and an index. Chapters in turn have pages, paragraphs and words. Show the special case of association between classes described here including the multiplicity.
Object Oriented Methodologies
Jerry Kotuba

18. Test Review See ICE’s on SLATE Plus Exercises 1,2,3,&4
Object Oriented Methodologies
Jerry Kotuba

19. Test Review Permitted a “cheat sheet”
Satzinger – Chapters 1,2,4,5,6 (Chap 6 only to page 225 –including Activity diagrams)
Plus all material covered in class…check PPTs
10 modified T/F and 15 M/C questions
Exercises
Event table
Use Case Diagram
Includes (a.k.a. Uses)
Activity Diagram
Class Diagram
Relationships ( Multiplicity)
Association Classes
Subclasses & Inheritance (incl. constraint & Discriminator Notation)
Generalization & Specialization
Abstract Classes
Permitted a “cheat sheet”
One 8 ½ X 11 sheet only (both Sides)
Object Oriented Methodologies
Jerry Kotuba

20. Next class…
Mid-term test
Object Oriented Methodologies
Jerry Kotuba

21. Your turn…ICE-05
SLATE2
Object Oriented Methodologies
Jerry Kotuba