1. Object-Oriented Analysis and Design: Object Modeling – Class Diagrams
Modern Systems Analysis and Design Seventh Edition Jeffrey A. Hoffer Joey F. George Joseph S. Valacich
Chapter 8 Appendix
Object-Oriented Analysis and Design:
Object Modeling – Class Diagrams

2. © 2014 Pearson Education, Inc. Publishing as Prentice Hall
Learning Objectives
Concisely define each of the following key data modeling terms: object, state, behavior, object class, class diagram, operation, encapsulation, association role, abstract class, polymorphism, aggregation, and composition.
Draw a class diagram to represent common business situations.
Explain the unique capabilities of class diagrams compared with E-R diagrams for modeling data.
Chapter 8 Appendix
© 2014 Pearson Education, Inc. Publishing as Prentice Hall

3. Representing Objects and Classes
Object: an entity with a well-defined role in an application domain; has state, behavior, and identity characteristics
State: encompasses an object’s properties (attributes and relationships) and the values of those properties
Chapter 8 Appendix
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4. Representing Objects and Classes (Cont.)
Behavior: represents how an object acts and reacts
Identity: uniqueness—no two objects are the same
Object class (class): a logical grouping of objects that have the same (or similar) attributes, relationships, and behaviors (methods)
Chapter 8 Appendix
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5. Representing Objects and Classes (Cont.)
Class diagram: a diagram that shows the static structure of object classes, their internal structure, and the relationships in which they participate
UML classes are analogous to E-R entities.
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6. Representing Objects and Classes (Cont.)
Figure 8-26 UML class diagram showing two classes
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7. Representing Objects and Classes (Cont.)
Operation: a function or a service that is provided by all the instances of a class to invoke behavior in an object by passing a message
Encapsulation: the technique of hiding the internal implementation details of an object from its external view
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Types of Operations
Constructor: an operation that creates a new instance of a class
Query: an operation that accesses the state of an object but does not alter the state
Update Operation: an operation that alters the state of an object
Class Scope Operation: an operation that applies to a class rather than an object instance
Chapter 8 Appendix
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9. Representing Associations
Association: a relationship among instances of object classes
Association role: the name given to the end of an association where it connects to a class
Chapter 8 Appendix
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10. Representing Associations (Cont.)
Multiplicity: indicates how many objects participate in a given relationship:
0..10 means minimum of 0 and maximum of 10
1, 2 means can be either 1 or 2
* means any number
UML associations are analogous to E-R relationships and UML multiplicities are analogous to E-R cardinalities.
Chapter 8 Appendix
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11. Representing Associations (Cont.)
Figure 8-27 Examples of association relationships of different degrees
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12. Representing Associations (Cont.)
Figure 8-28 Examples of binary associations
Chapter 8 Appendix
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13. Representing Associative Classes
Associative class: an association that has attributes or operations of its own or that participates in relationships with other classes
UML association classes are analogous to E-R associative entities.
Generalization and inheritance are implemented via superclass/subclasses in UML and via supertypes/subtypes in E-R.
Chapter 8 Appendix
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14. Representing Associative Classes (Cont.)
Figure 8-29 Class diagram showing associative classes
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15. Representing Stereotypes for Attributes
Figure 8-31 Stereotypes
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16. Representing Generalization
Abstract class: a class that has no direct instances but whose descendants may have direct instances
Concrete class: a class that can have direct instances
Chapter 8 Appendix
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17. Representing Generalization (Cont.)
Figure 8-32 Example of generalizations, inheritance, and constraints
Chapter 8 Appendix
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18. Representing Generalization (Cont.)
UML keywords:
Overlapping: a descendant may be descended from more than one of the subclasses
Disjoint: a descendant may not be descended from more than one of the subclasses
Complete: all subclasses have been specified
Incomplete: some subclasses have been specified, but the list is known to be incomplete
Chapter 8 Appendix
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19. Representing Generalization (Cont.)
Class-scope attribute: an attribute of a class that specifies a value common to an entity class, rather than a specific value for an instance
Chapter 8 Appendix
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20. Representing Generalization (Cont.)
Figure 8-33 Polymorphism, abstract operation, class-scope attribute, and ordering
Chapter 8 Appendix
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21. Representing Generalization (Cont.)
Abstract operation: defines the form or protocol of the operation, but not its implementation
Method: the implementation of an operation
Polymorphism: the same operation may apply to two or more classes in different ways
Chapter 8 Appendix
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22. Representing Aggregation
Aggregation: a part-of relationship between a component object and an aggregate object
Represented with open diamonds
Composition: a part object that belongs to only one whole object and that lives and dies with the whole
Represented with filled diamonds
Chapter 8 Appendix
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23. Aggregation and Composition
Figure 8-34 Aggregation and composition
Chapter 8 Appendix
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24. An Example of Conceptual Data Modeling at Hoosier Burger
Figure 8-35 Level-0 data flow diagram for Hoosier Burger’s new
logical inventory control system
Chapter 8 Appendix
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25. An Example of Conceptual Data Modeling at Hoosier Burger (Cont.)
Figure 8-36 Reduced decision table for Hoosier Burger’s inventory reordering
Chapter 8 Appendix
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26. An Example of Conceptual Data Modeling at Hoosier Burger (Cont.)
Figure 8-38 Final class diagram for Hoosier Burger’s inventory control system
Chapter 8 Appendix
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27. © 2014 Pearson Education, Inc. Publishing as Prentice Hall
Summary
In this appendix you learned how to:
Concisely define each of the following key data modeling terms: object, state, behavior, object class, class diagram, operation, encapsulation, association role, abstract class, polymorphism, aggregation, and composition.
Draw a class diagram to represent common business situations.
Explain the unique capabilities of class diagrams compared with E-R diagrams for modeling data.
Chapter 8 Appendix
© 2014 Pearson Education, Inc. Publishing as Prentice Hall

28. Copyright © 2014 Pearson Education, Inc. Publishing as Prentice Hall