c Manfred Kerber School of Computer Science
Alexandros Evangelidis University of Birmingham
Worksheet 4 5 November 2019
MSc/ICY Software Workshop
Assessed Worksheet: 3% of the module mark (5% for the 20cr version).
Submission Deadline is Tuesday, 19 Nov 2019, at 12:00 noon via Canvas.
Follow the submissions guidelines on Canvas. JavaDoc comments are mandatory.
All submissions must pass the tests provided on 12 Nov. For Exercises 1 – 3 submit own
tests.
Exercise 1: (Basic, MSc: 30%, ICY: 40%) Write a class Aircraft.java with the two field variables
passengerNumber and maxSpeed both of type int with a standard constructor, getter(s), setter(s), and
a toString method. Furthermore write a subclass Aeroplane.java with the additional field variable
fuelConsumption of type double. The class should contain a constructor, getter(s) and setter(s), and a
toString method. Make use of inheritance as far as possible.
Exercise 2: (Medium, 30%)
Let two interfaces for the two classes Subscription.java and SubscriptionPrime.java be given as
SubscriptionInterface.java and SubscriptionPrimeInterface.java. You find the interfaces in the
archive WS1-04-interfaces.zip on the Canvas page for the worksheet.
Subscription.java describes the subscription to a journal by the 3 field variables title, email, and
cost of types String, String, and int, respectively. The subclass SubscriptionPrime.java has the
additional field deliveryAddress of type String, indicating where hard copies of the journal should be
sent to. Make use of inheritance as far as possible.
Exercise 3: (Advanced, 30%) Assume a website for downloading music which has four classes, one
for representing a music title, MusicTitle.java, and three for user accounts. The class Account.java is
abstract with two subclasses AccountStandard.java for customers, and AccountAdministrator.java
for administrators. Each of the four classes is to implement a corresponding interface with the names
MusicTitleInterface.java, AccountInterface.java, AccountStandardInterface.java, and
AccountAdministratorInterface.java, respectively.
You can find the interfaces in a WS1-04-interfaces.zip file on the Canvas page for the worksheet.
You are supposed to write the four classes to add a (non-interactive) implementation of a very rudimentary
system.
The class Account has to have five field variables: name, salutation, email, password, and loggedIn of
types String, String, String, String, and boolean, respectively.
The subclass AccountStandard has the field variables balance, titlesBought, and failedLoginAttempts
of types int, ArrayList, and int, respectively. Furthermore, assume a fixed number of 3
maximal login attempts, stored in a public static final int MAXIMAL LOGIN ATTEMPTS variable.
The subclass AccountAdministrator has the field variable accounts of type ArrayList. An
administrator shall have the possibility to reset an account of a user by a method
public void resetAccount(Account account, String password). The method shall first reset the
password. For standard users (and only for standard users) it shall also reset the counter
failedLoginAttempts of failed login attempts to 0.
For the latter, you may make use of account instanceof AccountStandard to check whether the object
account is an instance of the subclass AccountStandard. If it is, it is still of type Account, but it can
be cast to the type AccountStandard using the standard type casting approach: (AccountStandard)
account.
Make use of inheritance as far as possible.
Exercise 4: (Executive Summary, MSc Students Only 10%) Write an executive summary on
the topic: “What is the rationale for the use of object oriented programming and which limitations are
overcome by the use of functions in Java?” The submission must be an accessible PDF document of two
pages (including title, author, date, and at least three references) using an 11pt font.