Object-Oriented Analysis and Design

IntroductionTom Perkins

Pages: 634

Pub Date: November 2006

Publisher: O'Reilly

by Brett McLaughlin, Gary Pollice, David West

• Head First Object-Oriented Analysis and Design

Print ISBN-13: 978-0-59-600867-3

Print ISBN-10: 0-596-00867-8

Head First Chapters1. Great Software Begins Here2. Gathering Requirements3. Requirements Change4. Analysis5. Handling Change

1. Small Changes lead to Big Problems2. Incorporating Flexibility

6. Software Architecture7. Bringing Order to Chaos8. Design Principles9. Iterating and Testing10. An OOAD Software Process

Obstacles• Not the “perfect” Introduction to Object

Orientation book• Examples in Java

– Rework in VB.NET or C#.NET• Approach too “Juvenile”

– Maybe– Incorporates many different features drawn from

learning theory and cognitive psychology• Not a course for “object oriented gurus”• Yet assumes some familiarity with object-

oriented coding

Approach

• Stick close to the book• As much code as possible• Walkthru’s• Get your hands dirty, become involved• Do the book exercises• Work with someone where possible• Participate in class discussions• Team Learning Experiments

Welcome to Objectville

“Foist, youse gotta speak da language!”

Learning Objectives• Be able to read and interpret a UML class

diagram• Be able to write a simple class in VB.NET or

C#.Net• Be able to write a class that inherits from

another class, changes some behavior and adds some behavior to the base class

• Be able to define polymorphism• Be able to identify what encapsulation is and

why it is important

Points of Interest

UML

Inheritance

set

set

setset

set

Polymorphism

Encapsulation

UML and Class Diagrams

Airplane

speed: int

getSpeed(): int

setSpeed(int)

Class Diagram

Member Variables

name:type

Name

Methods

name(parameters the method uses): return type

Basic Airplane Class

VB.NETPublic Class Airplane Private mSpeed As Integer

Sub New() End Sub

Public Sub SetSpeed(ByVal value As Integer)

mSpeed = value End Sub Public Function GetSpeed() As Integer Return mSpeed End FunctionEnd Class

C#.NETusing System;using System.Collections.Generic;using System.Text;

namespace Objectville_Demo_CS{ public class Airplane { private int speed; public Airplane(){ // constructor } public virtual void setSpeed(int speed) { this.speed = speed; } public virtual int getSpeed() { return speed; } }}

What doesn’t the Class Diagram give you?

• Variable scope – public, private, friend, etc– Full-blown UML does– Not usually needed

• Information about the constructor method for the class

• Details of what each method does

Inheritance

• Once class inherits behavior from another class

• Code keywords– VB: Inherits – C# uses : (colon) to indicate inheritance

• “Derived” class, subclass• “Base” class, superclass (vb – MyBase)

InheritanceVB.NETPublic Class Jet Inherits Airplane

Private Const MULTIPLIER = 2 Public Sub New() MyBase.New() End Sub

Public Overrides Sub SetSpeed(ByVal value As Integer) MyBase.SetSpeed(value * MULTIPLIER) End Sub Public Sub Accelerate() MyBase.SetSpeed(GetSpeed() * 2) End SubEnd Class

C#.NET public class Jet:Airplane { private const int MULTIPLIER = 2;

public Jet() : base() { } public override void setSpeed(int speed) { base.setSpeed(speed * MULTIPLIER); } public void accelerate() { base.setSpeed(getSpeed() * 2); } }

Base Class Modifications (.NET)

Public Class Airplane Private mSpeed As Integer

Sub New() End Sub

Public Overridable Sub SetSpeed( ByVal value As Integer) mSpeed = value End Sub Public Overridable Function GetSpeed() As Integer Return mSpeed End FunctionEnd Class

public class Airplane { private int speed; public Airplane() // constructor { } public virtual void setSpeed(int speed) { this.speed = speed; } public virtual int getSpeed() { return speed; } }

Putting the classes to workStart with a biplane

Module Module1

Sub Main() FlyTest() End Sub Public Sub FlyTest() Dim biplane As New Airplane biplane.SetSpeed(212) Console.WriteLine( _biplane.GetSpeed()) Console.Read() End Sub

End Module

static void Main(string[] args) { FlyTest1(); } public static void FlyTest1() { Airplane biplane = new Airplane(); biplane.setSpeed(212); Console.WriteLine(biplane.getSpeed());

Console.ReadLine(); }

Module Module1 ‘Puzzle 1 (VB)

Sub Main() FlyTest() End Sub Public Sub FlyTest() Dim biplane As New Airplane biplane.SetSpeed(___) Console.WriteLine(_________________)

Dim boeing As New Jet boeing.SetSpeed(___) Console.WriteLine(_________________) ______ While _______ ___________________ Console.WriteLine(________________) If (________________ > 5000) Then ________________(________________ * 2) Else _________________ End If _________ End While Console.WriteLine(biplane.GetSpeed) Console.Read() End Sub

End Module

212 Dim x = 0 boeing.GetSpeedbiplane.GetSpeed() biplane.SetSpeed boeing.GetSpeed biplane.Accelerate()biplane.GetSpeed 422 x < 5x < 4 boeing.SetSpeed x = 0 x < 3x = x + 1 424 boeing.Accelerate() x-- x = 1

212

844

1688

6752

13504

27008

1696

Code snippets:

Desired output:

static void Main(string[] args) // puzzle 1 C# { FlyTest1(); } public static void FlyTest1() { Airplane biplane = new Airplane(); biplane.setSpeed(___); Console.WriteLine(____________); Jet boeing = new Jet(); boeing.setSpeed(___); Console.WriteLine(________________); _________; while (________) { _________________; Console.WriteLine(_____________________); if ( ______________ > 5000) { __________________(______________ * 2); } else { ______________________; } ___________; } Console.WriteLine(biplane.getSpeed()); Console.ReadLine(); }

212 boeing.getSpeed()biplane.getSpeed() 422 x = 0int x = 0; x < 4 boeing.accelerate() biplane.setSpeed x-- x = 1 x < 3boeing.getSpeed() boeing.accelerate() boeing.getSpeed() biplane.getSpeed() x++ 424 x < 5

Code Snippets:

212

844

1688

6752

13504

27008

1696

Desired output:

DEMO

“Walkthru” of solution

A “toonce” of Polymorphism

Airplane speed: int

getSpeed(): int

setSpeed(int)

Jet MULTIPLIER: int

accelerate()

“inherits from”

Airplane plane = new Airplane(); Airplane plane = new Airplane();

Airplane plane = new Jet();

Airplane plane = new Rocket();

Encapsulation Escapades

• Hiding information from the rest of your application

• Hide the details within the object; use “Public” sparingly

• Demo – change the internal speed variable from “private” to “public”– Run FlyTest2 and FlyTest3

Rick’s Guitar Shop ApplicationUML Class Diagrams

Guitar serialNumber:string price: double builder:string type:string backWood:string topWood:string

getSerialNumber():stringgetPrice():doublesetPrice():doublegetBuilder():doublegetModel():stringgetType():doublegetBackWood():stringgetTopWood():string

InventoryGuitars: List

addGuitar(string,double,string,string,string,string,string)

getGuitar(string):Guitar search(Guitar):GuitarinitializeInventory:printInventory()

Main ApplicationInv:Inventoryg:GuitarwhatErinLikes:Guitar

initializeInventory(Inventory)

Demo

Walkthru Rick’s Guitar Shop Application

Problems

• Search routine does not work• Should use constants or enums instead of

strings• Search should return multiple guitars• Architecture could use some restructuring

• What would you do first with Rick’s app?

Assignment

• If your’re new to object oriented programming, read Appendix ii: Welcome to Objectville

• Work through exercises in Chapter 1• Download Rick’s App from class site• Modify it to:

– Fix the search routine– Use enums instead of strings