Individual Assessed Coursework

November 2022

 

Scenario:  Wine Direct is an attempt by a cooperative to sell their wine reserves directly to the public. Wine is only sold by the case. People who are interested in buying the wine have to submit their details online and, once accepted, are then given a unique ID which they can later use to log in and then to buy wine.  For the purposes of this assessment, you may assume that only one person can log onto the web site at any one time.

 

For this homework, you must use the names of fields (and all other variables and methods) as they are exactly specified in this document.

 

Noting also for method names that if you have a variable called numberOfTracks, then a mutator for this field is called setNumberOfTracks and the corresponding accessor is called getNumberOfTracks.

 

Overall specification: to write a simple Java class, WineDirect, that models a wine selling cooperative.

 

Step 1: A simple Browser class

Write a basic Browser class with three private fields, yearOfBirth, email (a String) and iD (which you can assume consists of a unique sequence of digits).  

 

There are going to be two kinds of browsers: those who already have an ID (and so can purchase the wine straightaway) and those who do not. Hence, you will need to write two constructors: one for each type of browser. One constructor will be passed three arguments (you may choose the order of these arguments) and the other will be passed two arguments (again, you may choose the order).

 

Now introduce a new field isBuyer and a method setBuyerStatus(), which is passed a boolean value as an argument.  This method will be used whenever the potential buyer logs into the Wine Direct website.

 

The class should include suitable accessor & mutator methods.

 

Step 2: A simple Website class

1. a) Write a simple Websiteclass to represent the web site.  The constructor for the class should be passed the name of the website which is then stored in a field name. A second field hitsshould record the number of buyers who log in to the website and a third field salesTotal which should record the amount of money taken at checkout.

 

1. b) As stated above, there are two types of browsers who access this web site: those who already have their ID i.e. buyers, and those who do not. Part of the web site allows the buyers to simply log in and to then buy a case of wine. Those who do nothave an ID must submit their personal details and, once these have been checked, then they too can buy wine.

 

Write a method for the class, called buyerLogin(), which allows a buyer to log in to the site. This method is passed a Browser object as a parameter and which for the moment simply outputs a welcome message to the terminal window in the format (assuming your chosen site name is Wine Direct) shown here:

Wine Direct welcomes buyer 6732, you are now logged in.

 

1. c) Next, write a method becomeBuyer()which is also passed a parameter that is a pointer to aBrowser object. This method then checks that the potential buyer is over the age of 18 and so is able to make a purchase. Of course, in real life more checks would have to be made J. You also don’t need to worry about checking for an accurate age i.e. you don’t need to include months and days in your calculation.

Anyhow, if the potential buyer is indeed old enough then this method sets the buyer’s iD field (but see the paragraph below) and then this method calls the method buyerLogin().

 

To set the browser’s iD field, you have a choice: either set it to 999 or, for more marks, set it to a random value. To do the latter, you need to use an object from the Random class as follows. Firstly, write the code import java.util.Random before the class header of Website. Then use the BlueJ Help menu to find out about the Random class and which method from that class it is most appropriate to use here.

 

Step 3: Add a basic WineCase class and allow a buyer to select a case of wine to buy.

 

1. Write a basic WineCaseclass to represent a case of wine.  A WineCase object has four fields: refNo (a unique sequence of letters and digits), description (e.g. “chablis”, “white burgundy” or similar), noOfBottles (in the case) and price (the price of the case in pounds).  The constructor for the class should be passed suitable arguments to initialise these four fields.
2. Add a selectWineCase()method to the Browser class which allows a browser to choose a case of wine provided that browser is a buyer. This method is passed a WineCase object as a parameter.  You should declare a new field wineCase in the Browser class in order to store the case of wine selected.

 

1. Make the selectWinecase()method print a message to the terminal window about the selection. An example is shown below:

Buyer with ID 6732 has selected wine case with reference

number LO786, a case of 2018 Pinot from Italy of 12 bottles

at £120

 

Step 4: Allow a buyer to pay for the case of wine.

1. Add a method payForWine()to the Browser  This method will simply call a method in the Website class to pay for the wine i.e. to record the transaction with the website.

 

And here we have a problem: at the moment the Website object does not record which browser has entered the store and, conversely, the Browser object also keeps no details of which site it has entered. Let’s deal with that now.

 

1. b) Add another field websiteto the Browser  This field will be used to store a reference (i.e. a pointer) to the website the browser is currently logged into.  Write a mutator method setWebsite().
   • Modify the buyerLogin()method of Website so that after the user is logged into the website, setWebsite() is called with a pointer to that website.

Think about what this value could be:

So, setWebsite() needs to be passed, as an argument, a pointer to the Website object that you are currently browsing. This will enable the Browser object to record which website it is logged into.

 

In fact, the Website object needs to be able to tell the Browser object “point to me”. That is, the Website object needs a pointer to itself.

 

And a pointer that points to the object itself is called a self-referencing pointer and has value this.

Amend your code to do this.

 

Next, complete payForWine() by adding a call to the method checkout() of the Website class. What parameters do you think checkout() will need? Try working this out for yourself and then to check, read c) below which details the parameters needed.

 

1. c) Add a method checkout()to the Websiteclass which is passed a parameter which is a pointer to a Browser object representing the browser wishing to purchase a case of wine.  The checkout() method should print a message to a terminal window confirming successful completion of the transaction.

 

1. d) It is decided to give a discount of 10% to every 10^thbuyer who logs into the website — if they select and pay for a case of wine during this login session then they will receive a 10% discount at checkout.Add a method checkHitDiscount() to the Website class which checks whether a discount is available. Amend your checkout() method to use this new method and, if appropriate, to print a congratulatory message to the screen and, of course, to reduce the cost of the wine(s).