In class exercise (I)In class exercise (I)

Problem specification:Problem specification:An e-commerce company based in An e-commerce company based in

Maryland, U.S. called Dogwood, needs Maryland, U.S. called Dogwood, needs an online sale system. You are asked an online sale system. You are asked to write the part of the system to deal to write the part of the system to deal

with sale order.with sale order.

Stage OneStage One• Step I. Create the class library for sale order

Implement the sale order class according to the following specification. Please note that this class is not responsible for getting input from users. You must assume that the information needed is passed in through its constructor. Class Attributes OperationsSaleOrder customName, Calculate price before tax Calculate

itemSold, Calculate tax amountitemQuantity, Calculate total priceunitPrice Display a receipt with custom name,

item sold,quantity, unit price, tax amount and total price.

• Step II. Write an application using the sale order libraryWrite an application to test the above class you create. Basic things you need to do are to create an object of SaleOrder and to see if the receipt is displayed properly.

First SaleOrderFirst SaleOrder Design DesignSaleOrder

-itemQuantity: integer-unitPrice: double-itemSold: string

-customerName: string

+calTax(): double…

double calcTax(){ return itemQuantity*unitPrice*0.05;}

Result of Stage One:Result of Stage One:• Your library works so

well for Dogwood• Another two e-

commerce companies based in Maryland, Elm and Holly, bought your library and used it in their on-line sale application as well.

Stage Two:Stage Two:

• Requirement changes:Dogwood’s business is booming and they decide to extend their business to Delaware.

You are asked to rewrite the sale order library to deal with the taxation rule with both Maryland and Delaware.

• Step I. Changing requirement leading to changing sale order library

• Step II. Write an application using the new sale order library

Write an application to test the above class you create. Basic things you need to do are to create an object of SaleOrder and to see if the receipt is displayed properly for both Maryland and Delaware customers.

Result of Stage Two:Result of Stage Two:• Your library works so well

for Dogwood’s business in Delaware and Maryland.

• You also sold your new library to an Delaware and Maryland e-commerce firm called Chestnut.

• Due to your change to sale order library, Elm and Holly are affected.

Stage Three:Stage Three:

• Requirement changes:Dogwood’s business is booming again and they decide extend their business to the rest of U.S. You are asked to rewrite the sale order library to deal with the taxation rule with all the states in U.S..

• Step 0. Before we do anything, we need to sit back and think first.

What got us into this

mess?

Identify the changing

partHow can we make

our design

flexible?design

Requirement changes

What is changing in sale order?

Implement changes without

affecting the existing

tax and how tax is calculated

Separate changing

part

New SaleOrderNew SaleOrder Design Design

SaleOrder…

-saleTax: SaleTax

+calTax(): double…

USTax

+calTax(…): double

CanadaTax

+calcTax(…): double

GermanyTax

+calcTax(…): double

<<interface>>SaleTax

+calcTax(…): double

double calcTax(){ return saleTax.calcTax(…);}

• Step 1. Implement the new sale order class according to the new design

• Step II. Write an application using the new sale order library

Write an application to test the above class you create. Your application should be something like:

SaleOrder saleOrder1 = new saleOrder(“Joe”,“appletSeed”,10,1.0, new USTax());

SaleOrder saleOrder2 = new saleOrder(“Mary”,“roseTree”,2,25.0, new CanadaTax());

Change requirement on tax Change requirement on tax calculation on old designcalculation on old design

SaleOrder

-itemQuantity: integer-unitPrice: double-itemSold: string

-customerName: string

+calTax(): double…

App1

App2

App3

App4

Change requirement on tax Change requirement on tax calculation on new designcalculation on new design

SaleOrder…

-saleTax: SaleTax

+calTax(): double…

USTax

+calTax(…): double

CanadaTax

+calcTax(…): double

GermanyTax

+calcTax(…): double

<<interface>>SaleTax

+calcTax(…): double

App1

App2App3

NewZealandTax

+calTax(…): double

App4

In class exercise (II)In class exercise (II)Problem One Specification:Problem One Specification:

1.1. You and your friend started a company to deliver software You and your friend started a company to deliver software solution to customer problem. solution to customer problem.

2. Your first business is from Salisbury University Register’s 2. Your first business is from Salisbury University Register’s office. They are using a class library to keep course office. They are using a class library to keep course information. Their current class library allow to sort the information. Their current class library allow to sort the students list using a selection sort. students list using a selection sort.

3. Now they ask you to improve the design to allow different 3. Now they ask you to improve the design to allow different sorting strategy being used.sorting strategy being used.

Current Course ClassCurrent Course Class Design DesignCourse

-title: string-instructor: string-students: string[]

……

+sortStudents(): void…

void sortStudents(){ // selection sort of students array

… …}

Course calcII = new Course(…);…calcII.sortStudents();…

Application

New Course ClassNew Course Class Design DesignCourse

-title: string-instructor: string-students: string[]

??????

+sortStudents(): void…

void sortStudents(){ // sort of students array

??????}

Course calcII = new Course(…, new BubbleSort()); or calcII.setSortStrategy(new BubbleSort());

calcII.sortStudents();…

Application

Problem Two Specification:Problem Two Specification:

1. Your second business is from Perdue Stadium 1. Your second business is from Perdue Stadium Ticket Office. They asked you to write a class Ticket Office. They asked you to write a class library to calculate ticket sale price.library to calculate ticket sale price.

2. Here are the rule for ticket sale at Perdue 2. Here are the rule for ticket sale at Perdue Stadium:Stadium:

- Ticket sale price consist of two parts: ticket price and sale tax.

- Ticket price also varies between children, and adult.

• Short sighted with quick and dirt approach

• Long term with solid and clear approach

Your viewYour view

SaleOrderSaleOrder Design Design

SaleOrder…

-saleTax: SaleTax

+calTax(): double…

USTax

+calTax(…): double

CanadaTax

+calcTax(…): double

GermanyTax

+calcTax(…): double

<<interface>>SaleTax

+calcTax(…): double

double calcTax(){ return saleTax.calcTax(…);}

BubbleSort+sort(string[]):void

SelectionSort+sort(string[]):void

QuickSort+sort(string[]):void

<<interface>>SortStrategy

+sort(string[]):void

Course

-title: string-instructor: string-students: string[]

-sortStrategy: SortStrategy

+sortStudents(): void+setSortStrategy(SortStrategy): void

void sortStudents(){ // sort of students array sortStrategy.sort(students);}

US+getAmt(…):doubld

Canada+getAmt(…):double

Germany+getAmt(…):double

<<interface>>TaxStrategy

+getAmt(…):double

TicketSale

-priceStrategy: PriceStrategy-taxStrategy: TaxStrategy

…

+getAmt(): double

double getAmount(){ return priceStrategy.getAmt(…)

+ taxStrategy.getAmt(…);}

Senior+getAmt(…):doubld

Children+getAmt(…):double

Adult+getAmt(…):double

<<interface>>PriceStrategy

+getAmt(…):double