1. Object Oriented Programming
Lecture 12
Object Oriented Programming
Richard Gesick

2. Topics Identifying Classes & Objects Class Relationships “this”
Parameters
Overloading
Methods
Operators

3. Identifying Classes & Objects
Identify potential classes within the specification
Nouns

4. What Goes in the Class How do you decide what should be in the class
Data
Methods

5. Class Relationships
Classes can have various relationships to one another. Most common are:
Dependency (“uses”)
Aggregation (“has a”)
Inheritance (“is a”)

6. Object Relationships
Objects can have various types of relationships to each other
A general association is sometimes referred to as a use relationship
A general association indicates that one object (or class) uses or refers to another object (or class) in some way
We could even annotate an association line in a UML diagram to indicate the nature of the relationship
Author
Book
writes

7. Dependency One class dependent (uses) another class
Game uses ball, paddle
Ship uses bullet
Sometimes, a class depends on another instance of itself
Is one date equal to another date?
Is one picture equal to another picture?

8. Aggregation One class is “made up” of other classes
“has a” relationship
Gameboard has a marble
Deck has a card

9. Aggregation
An aggregate object is an object that contains references to other objects
For example, an Account object contains a reference to a String object (the owner's name)
An aggregate object represents a has-a relationship
A bank account has a name
Likewise, a student may have one or more addresses

10. Aggregation in UML
An aggregation association is shown in a UML class diagram using an open diamond at the aggregate end
StudentBody
+ Main (args : String[]) : void
+ ToString() : String 1 2
Student
- firstName : String
- lastName : String
- homeAddress : Address
- schoolAddress : Address
- streetAddress : String
- city : String
- state : String
- zipCode : long
Address

11. UML Diagrams
classes are represented with boxes that contain three compartments:
The top compartment contains the name of the class.
The middle compartment contains the attributes of the class.
The bottom compartment contains the methods and properties

12. UML Diagrams Player - name:string -money:float -health: int +Player():
+Buy(float):void
+GetName():string
+Name:string {property}
+Money:float {property}
+ToString():string