Prutt05 Tentamen

1
Prutt05 Tentamen

• Model Answers
• Note that many variations are possible to obtain
  full marks.

2
Q1.
0,1
1
1
Shopping_Cart
List_of_Item
totalPricefloat
Item purchase
1
totalDiscountfloat
clubMemberbool
Add(Item purchase)
Delete(Item purchase)
itemCountint
Delete( )
Add(Item purchase)

Delete(Item purchase)

Item
Delete( )
Pricefloat
checkout( )
DiscountOnPricefloat
ShoppingCart(Item purchase )
QuantityInt
Book
Clothing
DVD
authorString
sizeInt
artistString
titleString
descriptionString
titleString
MensClothing
WomensClothing
ChildrensClothing
3

• Q1.(iii)
• Add(Item purchase)
• if (purchase.Quantity gt0)
• this.theItemList.add(purchase)
• purchase.Quantity--
• this.itemCount
• if (purchase instanceOf Clothing
  clubMember1)
• (purchase instanceOf Book clubMember2)
• (purchase instanceOf DVD clubMember3)
• this.totalPrice ( purchase.Price -
  purchase.DiscountOnPrice)
• else this.totalPrice purchase.Price
• else
• // throw an exception OutOfStock error?
• // of Add()

4

• Q2.(i)
• Precondition user has entered the web site. No
  shopping cart exists yet.
• Actors end_user
• Scenario
• The user clicks on an item and selects purchase
  option.
• A new ShoppingCart object is created, and its
  List_Of_Item component is initialised to contain
  the purchase.
• Repeated any finite number of times
• 2.a The user clicks on an item and selects the
  purchase option. The item is added to the
  ShoppingCarts List_Of_Item attribute. OR
• 2.b The user clicks on an item in the
  ShoppingCart and selects the delete option. The
  item is deleted from the ShoppingCarts
  List_Of_Item attribute.
• 3.a. The user clicks on the checkout button,
  OR
• 3.b The user clicks on the empty shopping cart
  button.
• Postcondition User has placed an order and
  shopping cart is deleted, or else no order and
  shopping cart is empty but still exists.

5
Shopping_Cart
List_Of_Item
ShoppingCart(purchase)

Alt
Add(purchase)
Add(purchase)
Delete(purchase)
Delete(purchase)
Alt
Checkout()
Delete()
Delete()
6

• Q4
• import junit.framework.TestCase
• public class Shopping_Cart_Test extends TestCase
  
• private Shopping_Cart testCart
• private Book testBook new Book(Title1,
  Author1, 10.99, 1.00, 10)
• // 10 copies in store at 10.99 each, discount
  1.00
• private Book testBook2 new Book(Title2,
  Author2, 11.99, 2.00, 20)
• // 20 copies in store at 11.99 each, discount
  1.00
• protected void setUp()
• testCart new Shopping_Cart() // no items
• clubMember2 True
• testCart.addItem(testBook) // setup with a
  first item
• protected void tearDown() // not needed

7

• Q3.
• For such a small project XP or COTS would seem to
  be the best models. There
• seems to be no room for large documentation.
  However both these approaches
• will satisfy any bank needs for project
  visibility. Study the course notes further to
• appreciate the consequences of these two choices.
  Consider also the many
• disadvantages of the spiral model and waterfall
  model in this case. Lastly, rapid
• prototyping doesnt seem necessary here, as the
  product is quite well understood.
• (We may even be able to buy most of it off the
  shelf!).

8

• Public void testAdd() // add an item and then
  check its there
• testCart.addItem(testBook2)
• assertEquals(testCart.totalPrice, 9.99 9.99)
• assertEquals(testCart.itemCount, 2)
• assertEquals(testCart.totalDiscount, 2.00
  1.00)
• assertEquals(testBook2.getQuantity(), 19)
• // testBook2 is still in the cart
• Public void testDelete(Item purchase) throws
  ItemNotFoundException
• // delete an item and check its gone i.e. back
  in store
• testCart.delete(testBook2)
• assertEquals(testCart.totalPrice, 9.99)
• assertEquals(testCart.itemCount, 1)
• assertEquals(testCart.totalDiscount, 1.00)
• assertEquals(testBook2.getQuantity(), 20)

9

• Public void testDeletItemNotInCart() // try to
  delete a non-existent item,
• // is this possible via the user interface?
  Maybe?
• try
• private Book testBook3 new Book(Title3,
  Author3, 10.99, 1.00, 10)
• testCart.delete(testBook3)
• fail(Should raise an ItemNotFoundException)
• catch (ItemNotFoundException e) //passes the
  test
• public void testDelete() // empty the cart and
  it should be empty!
• testCart.delete()
• assertEquals(testCart.itemCount, 0)
• assertEquals(testCart.totalPrice, 0.0)

10

• Q5.
• ltDOCTYPE Shopping_Cart
• lt!ELEMENT Shopping_Cart (Shopper, Book, DVD,
  Clothes)gt
• lt!ATTLIST Shopping_Cart totalPrice REQUIREDgt
• lt!ATTLIST Shopping_Cart totalDiscount REQUIREDgt
• lt!ATTLIST Shopping_Cart itemCount REQUIREDgt
• lt!ATTLIST Shopping_Cart dvdMember (TRUEFALSE)
  FALSEgt
• lt!ATTLIST Shopping_Cart bookMember (TRUEFALSE)
  FALSEgt
• lt!ATTLIST Shopping_Cart clothingMember
  (TRUEFALSE) FALSEgt
• lt!ELEMENT Book (Title, Author)gt
• lt!ELEMENT Title (PCDATA)gt
• lt!ELEMENT Author (PCDATA)gt
• lt!ATTLIST Book Price REQUIREDgt
• lt!ATTLIST Book DiscountOnPrice REQUIREDgt
• lt!ATTLIST Book Quantity REQUIREDgt

11

• lt!ELEMENT DVD (Title, Artist)gt
• lt!ELEMENT Title (PCDATA)gt
• lt!ELEMENT Artist (PCDATA)gt
• lt!ATTLIST DVD Price REQUIREDgt
• lt!ATTLIST DVD DiscountOnPrice REQUIREDgt
• lt!ATTLIST DVD Quantity REQUIREDgt
• lt!ELEMENT Clothing (Style, Size, Description)gt
• lt!ELEMENT Style (PCDATAMensClothingWomensClothi
  ngChildrensClothing)gt
• lt!ELEMENT Size (PCDATAXSSMLXL)gt
• lt!ELEMENT Description (PCDATA)gt
• lt!ATTLIST Clothing Price REQUIREDgt
• lt!ATTLIST Clothing DiscountOnPrice REQUIREDgt
• lt!ATTLIST Clothing Quantity REQUIREDgt

12

• lt?xml version1.0 encodingUTF-8?gt
• ltShopping_Cart totalPrice11.99, itemCount1,
  totalDiscount1.00,
• dvdMemberTRUE, bookMemberTRUE,
  clothesMemberTRUEgt
• ltBook price11.99, discount_On_Price1.00,gt
• ltTitlegtMyTitlelt/Titlegt
• ltAuthorgtMyAuthorlt/Authorgt
• lt/Bookgt
• lt/Shopping_Cartgt
• Q6. The problem here is that item prices need to
  be synchronised. If this is done
• then it is not possible for cusomers to access
  them while they are being changed.
• If they are not synchronised then race can
  occur, which leads to the
• phenomenon described in the question. Study the
  course notes in order to
• appreciate how to make changes to the code.