CSIT 2008 June 28, 2008 Anita Verno, Bergen Community College,

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1 CSIT 2008 June 28, 2008 Anita Verno, Bergen Community College,

2 Introducing OOD, An Example Design Methodologies Alphabet Soup: OOA, OOD, OOP Slides for an Introductory Lesson Why OOD? Terminology Suggestions Projects: The Good, The Bad, The Ugly

3 Introductory Lesson

4 Use a dog, cat, or whatever pet works for your class Ask 3 students to describe their dogs Lead to color, fur type, breed, age = attributes/properties Lead to speak, walk, sit, fetch, eat = methods/behaviors Show that dogs are described using the same attributes & methods Ask if go out today to get a dog will your dog have different attributes & methods? (OK this is a partial list)

5 Dog is a class Lassie is an object of that class Spot is also an object of the same class Write the class information in a comfortable form; exact UML syntax can wait for another time MyDog is instantiated when it is born = created according to the blueprint of the class Compare the terms of class, instantiation, object with blueprint, build, house

6 Class Build Instantiation Object

7 MyDog encapsulates the properties and methods It comes with a breed, color, etc. It can eat, walk, etc. I do not have to tell the dog how to eat and walk; the details are hidden.

8 Interface Human gives command to MyDog MyDog processes command MyDog sends signal that the task is complete Abstraction Human does not need to know how the dog accomplished the task (ex: eat) to give the command; only that it was done

10 OOD Think in terms of objects that are described Examples Student Dog Car Menu Option button Credit Card Receipt TOP DOWN Break problem into tasks and data Examples StudentEnroll StudentGrade CarGo CarCrash DogName CarColor

11 Step 1: OOA Object Oriented Analysis Analyze problem using comparisons to real world objects Step 2: OOD Object Oriented Design Describe each object in terms of data and actions Step 3: OOP Object Oriented Programming Create a program that contains one or more objects

12 Example Slides

13 Real world Use familiar objects to solve problems Makes problem solving much easier Increases ability to re-use Saves programmer time therefore money

14 Objects are the basic building blocks of a program Two possibilities: Use existing objects Ex: Add multimedia player to program No need to code or know all the inner details Only need to know how to use it: start, stop, play, pause Create your own objects Write the code Need to understand all details of the object and code each action

15 Object anything / something Student Dog Car Menu Button Credit Card Receipt

16 Every object has Attributes / properties This is the data Describes the object Methods / behaviors These are the actions = subprograms What can this object do?

17 Wristwatch Attributes: Dial Hour hand Minute hand Case Behaviors Keep track of time Set hour Set minute

18 Class Blueprint used to create object Every object comes from a class Class encapsulates all the attributes and methods Keeps them in 1 unit Object created from a class = instance of that class Process = instantiating Memory allocated Class variables initialized

19 My fossil watch is an instance of the class watch. It is an object. Lassie is an instance of the class dog. She is an object.

20 Abstraction There is more to the class than the programmer can use Hiding the internal details of an object from the user Why? Helps prevent the user from making inadvertent changes to the object Ensures object is only used in predetermined ways

21 Hidden attributes / methods The internal workings of my watch are hidden from the user Exposed attributes / methods The button to set the time is exposed to the user Expose only the attributes / methods needed to use object; Hide everything else!

22 Polymorphism one action causes something different to happen depending upon the object involved Ex: Open the house door is a different process than open the car door or open a book Ex: Calculations You use operators like + or for addition and subtraction regardless of the data type

23 Inheritance You can create one class from another class Original class base class Derived class Inherits the attributes and behaviors of the original class Include additional attributes and behaviors If you modify the original class, all the classes based on that change are updated automatically.

24 BASE CLASS FOSSIL WATCH NO ALARM DERIVED CLASS FOSSIL WATCH BLUE TOOTH, ALARM

25 MATCH THE FOLLOWING ITEMS TO THE CLOSEST EXAMPLE: A inheritance B polymorphism C encapsulation D instantiation E class 1 When a function takes on different meanings based upon what object is being used. 2 The hiding of the details of the implementation from a developer. 3 The ability to create a new class based on the definition of an existing one. 4 The blueprint of an object. 5 The creation of an object from a class

27 Teach using real world objects that are in the student s domain KISS Keep it Sweet and Simple Don t worry about exact professional representation That can come later, if at all Find a consistent way to model an object that is comfortable for the students.

29 Design a simple class and use it in a program Then use the class again in another program Divide students into teams; Students work individually Student 1 designs and codes a class and stores on a server Student 1 provides info regarding the visible class properties and methods Student 2 & 3 call the class within their application

30 Divide students into teams; Students work together Team 1 designs and codes several classes and stores them on a server Team 1 provides info regarding the visible class properties and methods to peers Team 2 develops the application that calls the classes Demonstrate the power of classes by using freely available classes

31 Are abstract; objects are not in the student s domain Expect too much KISS My measure: If I am having a hard time writing a clear project description in a single paragraph it s too complex

Reliance on terminology rather than concept Rigorous enforcement of professional standards in representation Use a simple method of diagramming that

32 Reliance on terminology rather than concept Rigorous enforcement of professional standards in representation Use a simple method of diagramming that helps students relate to the concepts ces/ians/se6/pdf/object oriented design.pdf, (downloaded on 3/25/2008)

35 OOD&i=48234,00.asp (downloaded 3/20/2008) 2%2Ct%3Dobjectoriented+programming&i%3D48238%2C00.asp (downloaded 3/20/2008) a&channel=s&rls=org.mozilla:en US:official&defl=en&q=define:object+oriented+desig n&sa=x&oi=glossary_definition&ct=title (downloaded 3/22/2008) (downloaded 3/12/2008)

36 ns/se6/pdf/object oriented design.pdf (downloaded 3/25/2008) ring/objectorienteddesign.shtml (downloaded 4/1/2008) Zak, Diane. Microsoft Visual Basic 2005: RELOADED, Second Edition. Boston: Thomson Course Technology, oriented_analysis (downloaded 3/12/2008) (downloaded 3/12/2008)

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