Difference between revisions of "OOP Class5"

Revision as of 16:32, 9 October 2007

This keyword

The this keyword used within a class refers to the current instance of the class

<csharp>public Time( int CurrentYear, int CurrentDay) {

this.Year = CurrentYear;
this.Day = CurrentDay;

}</csharp>

What is UML

UML 

Unified Modeling Language.

"A modeling language is a language whose vocabulary and rules focus on the conceptual and physical representation of a system"

The Unified Modeling Language User Guide, Booch Rumbaugh Jacobson ACM Press, Addison Wesley 1999 ISBN 0201571684 The Unified Modeling Language User Guide

Simple Notation

Class notation in UML

The name of the Class should go inside of a box

Then Two lines are added. The first line separates Attributes. The second line separates Operations. Attributes are the equivalent of fields or properties in c# and Operations are the same as methods.

A Rectagle Class might look like this

You can also specify Attribute types with a :

Default vlaues are specified with =

Operator return type are also specifed with a :. Opertor parameter signatures are specified by ( name : Type )

UML Resources

Dia A Drawing Program

Dia for windows

Dog Diagrams with Dia

Dog Exmaples

Simple Dog Class from week 5 DogSimple.cs - source
<csharp>using System;

//Dog simple class definition public class Dog {

	public string Name;		// the dog's name

public int Age; // the dog's age public int Weight; // the dog's weight public string BarkSound; // the sound of the dog's bark

public Dog() { BarkSound = "Woof!!!"; }

public void Bark() { //put bark code here } public void Eat() { //put eat code here } }</csharp>

Dog UML with Types

Dog Class with Types from week 4 DogWithTypes.cs - source

<csharp>using System;

//Dog simple class definition public class Dog {

	public string Name;		// the dog's name

private int Age; // the dog's age public int Weight; // the dog's weight public string BarkSound; // the sound of the dog's bark private int barkCount; //The number of time the dog has barked public Dog() { BarkSound = "Woof!!!"; }

public string Bark() { string strBark = this.BarkSound;

       barkCount ++;
       return strBark;

}

public void Eat() { //put eat code here } }</csharp>

Inheritance - 'Is A'

ArsDigita University Course 04: Object-oriented Program Design and Software Engineering - Lecture Notes 3

C# supports single class inheritance only. Therefore, you can specify only one base class to inherit from.

A Basenji is an African barkless dog. A Basenji is a dog. syntax

<csharp>public class Basenji : Dog {

   //override constructor
   public Basenji() : base()
   {
       barkSound = "Basenjis don't bark, but they do howl and growl.";
       dogCount++;
   }
   public override void Bark()
   {
       Console.WriteLine("Basenjis dont bark.");
   }

// some more code.... }

public class Dog { // some dog code... //methods need to be marked virtual or protected to be overridden

   public virtual void Bark() 
   { 
       //make dog bark
       Console.WriteLine (this.Name + " says " + this.barkSound);
       //add 1 to the number of times the dog has barked
       this.barkCount++ ;
   }

}</csharp>

Basenji.cs -source

Virtual Functions

A class modifier that indicates that a method can be overridden by a derived class. We will look at virtual function when we look at abstract classes

Abstract Classes

abstract - A class modifier that specifies that the class must be derived from to be instantiated.

<csharp>abstract public class Mammal { private string birth; private string skin;

public Mammal() { birth = " gives birth to live young."; skin = " has Hair."; }

public string Birth { get { return birth; } } public string Skin { get { return skin; } } }</csharp>

Inheritance example /infod/jeff/classSource/class5/DogMammal.cs -source

Polymorphic Types

Polymorphism (computer science) Different types implementing the same functionality.
polymorphism webopedia The C# Station Tutorial - Lesson 9: Polymorphism

<csharp>abstract public class Mammal { private string name; private string birth; private string skin;

public Mammal() { name = "none"; birth = " gives birth to live young."; skin = " has Hair."; }

public Mammal(string newName) { name = newName; birth = " gives birth to live young."; skin = " has Hair."; }

public string Birth { get { return birth; } } public string Skin { get { return skin; } } public string Name { get { return name; } set { name = value; } } public virtual void Bark() { Console.WriteLine("Some Mammals Bark."); } }

public class Dog : Mammal { public string BarkSound; // the sound of the dog's bark

public Dog(string newName) { Name = newName; BarkSound = "Woof!!!"; }

public override void Bark() { base.Bark(); Console.WriteLine(this.Name + " says " + this.BarkSound); } public void Eat() { //put eat code here } }

public class Basenji : Dog { //override constructor public Basenji(string newName) : base(newName) { BarkSound = "basenjis don't bark, but they do howl and growl."; }

public override void Bark() { base.Bark(); Console.WriteLine("\nBasenjis dont bark."); }

   // some more code....

}</csharp>

DogPoly.cs -source

HomeWork

READ

1. Chapter 9 Inside Methods p 111-123
2. Chapter 11 Inheritance and Polymorphism p 134-154
3. Chpater 12 Operator Overloading p 155 - 172
4. chapter 13 Structs p 172 - 177 (relax its only 54 pages total)

DO

Extend the class that you worked on last week.
.

Demonstrate

• Containment 'Has A'
  • Make a class that contains or is contained by your old class
• Association - 'Uses A'
  • Make a class that uses your original class

Extra credit add two dags

roover = fido + milo;

Quiz 2 next week

Links

The C# Station Tutorial - Lesson 7: Introduction to Classes
The C# Station Tutorial - Lesson 8: Class Inheritance
The C# Station Tutorial - Lesson 9: Polymorphism
The C# Station Tutorial - Lesson 10: Properties
The C# Station Tutorial - Lesson 12: Structs
The C# Station Tutorial - Lesson 13: Interfaces
The C# Station Tutorial - Lesson 4: C# Fundamentals