1. LESSON05 Jerry Kotuba Object Oriented Methodologies 1

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

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 Jerry Kotuba 3 SYST39409 - Object Oriented Methodologies

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 Jerry Kotuba 4 SYST39409 - Object Oriented Methodologies

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 Jerry Kotuba 5 SYST39409 - Object Oriented Methodologies

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

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. Jerry Kotuba Object Oriented Methodologies 7

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. Jerry Kotuba Object Oriented Methodologies 8

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

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

11. Aggregation and Composition. Jerry Kotuba Object Oriented Methodologies 11

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. Jerry Kotuba Object Oriented Methodologies 12

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. Jerry Kotuba Object Oriented Methodologies 13

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. Jerry Kotuba Object Oriented Methodologies 14

15. Assemblies of parts Vs Containers and their contents  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.  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!) Jerry KotubaObject Oriented Methodologies 15

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 KotubaObject Oriented Methodologies 16

17. Your Turn… Jerry Kotuba Object Oriented Methodologies 17 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.

18. Next class… Jerry Kotuba Object Oriented Methodologies 18  Wrap-up Class Diagrams  Test Review  Return Assignment No 1  Quiz No 2

19. Your turn…ICE-05  SLATE2 Jerry Kotuba Object Oriented Methodologies 19