Comp249- Assignment 2
Object-Oriented Programming II – Assignment 2
Purpose: The purpose of this assignment is to practice class inheritance, and other Object Oriented
Programming concepts such as constructors, access rights, method overriding, etc. The assignment would
also allow you to practice the notion of package creation. This assignment contains two parts. You need
to complete part I to be able to do part II. You should however handle each part as if it was a separate
assignment (i.e. you should not modify Part I after finishing with it; rather create a copy of that part and
use it to create Part II. This is needed so that you can finally submit both parts!
Various flying objects can be described as follows:
− An Airplane class, which has the following attriobutes: a brand (String type), price (double type)
and horse power (int type).
− A Helicopter is an Airplane that additionally has the
following: a number of cylinders (int type), a creation
year (int type), and a passenger capacity (int type).
− A Quadcopter, is a Helicopter that additionally has the
following: max flying speed (int type), which indicates its
maximum moving speed.
− A Multirotor is a Helicopter that additionally has the
following: number of rotors (int type), which indicates its
number of rotors/blades that it has.
− A UAV (Unmanned aerial vehicle / Drone) class has the
following attributes: weight (double type), and price
** All images have been obtained from, and © wikipedia.org
Comp249/Winter 2020 – Assignment 2 Page 2 of 4
− An AgriculturalDrone (which is used for crop
production) is UAV that additionally has the following:
brand (Sting type), and carry capacity (int type).
− A MAV (Micro Air Vehicle), is a miniature UAV that
has a size restriction (and can be as small as few
centimeters. It has the following: model (String type) and
size (double type).
1. Draw a UML representation for the hierarchy of the above-mentioned classes. Your representation
must also be accurate in terms of UML representation of the different entities and the relation
between them. You must use a software to draw your UML diagrams (no hand-writing/drawing is
2. Write the implementation of the above-mentioned classes using inheritance and according to the
specifications and requirements given below:
• You must have 5 different Java packages for the classes. The first package will include the
Airplane class. The second package will include the Helicopter, and the Quadcopter classes.
The third package will include the Multirotor class. The fourth package will include UAV class,
and the last package will include the AgriculturalDrone and MAV classes.
• For each of the classes, you must have at least three constructors, a default constructor, a
parametrized constructor (which will accept enough parameters to initialize ALL the attributes of
the created object from this class) and a copy constructor. For instance, the parametrized
constructor of the Quadcopter class must accept 7 parameters to initialize the brand, the price,
the horse power, the number of cylinders, the creation year, the passenger capacity, and the
maximum flying speed.
• An object creation using the default constructor must trigger the default constructor of its ancestor
classes, while creation using parametrized constructors must trigger the parametrized constructors
of the ancestors.
• For each of the classes, you must include at least the following methods: accessors, mutators,
toString() and equals() methods (notice that you are always overriding the last two methods).
− The toString() method must return clear description and information of the object (i.e “This
Agricultural Drone is manufactured by Agridrones. It weights 340 pounds, and costs 98000$.
It can carry up to 25 Kg….).
− The equals() method must first verify if the passed object (to compare to) is null and if it is of
a different type than the calling object. The method would clearly return false if any of these
conditions is true; otherwise the comparison of the attributes is conducted to see if the two
objects are actually equal. Two objects are equal if the values of all their attributes are equal.
• For all classes you must use the appropriate access rights, which allow most ease of use/access
without compromising security. Do not use most restrictive rights unless they make sense!
Comp249/Winter 2020 – Assignment 2 Page 3 of 4
• When accessing attributes from a base class, you must take full advantage of the permitted rights.
For instance, if you can directly access an attribute by name from a base class, then you must do
so instead of calling a public method from that base class to access the attribute.
3. Write a driver program (that contains the main() method) that would utilize all of your classes.
The driver class can be in a separate package or in any of the already existing packages. In the
main() method you must:
• Create various objects from the 7 classes, and display all their information (you must take
advantage of the toString() method).
• Test the equality of some of the created objects using the equals() method.
• Create an array of 15 to 20 these flying objects (HINT: Do you need to add something
else to the classes described above? If so; go ahead with that!) and fill that array with
various objects from these classes (each class must have at least one entry in that array).
• Trace(search) that array to find the two objects that have the least expensive price (that is
least expensive and second least expensive). Display all information of these two objects
along with their location (index) in the array.
In that phase, you need to modify/expand the implementation from Phase I as follows:
1. In the driver program, you need to add another static method (add it above the main() method),
called copyFlyingObjects. The method will take as input an array of these objects (the array can
be of any size) and returns a copy of that array. That is to say, the method needs to create an
array of the same length as the passed array, copies all objects from the passed array to a new
array, then returns the new array. Your copy of the objects will automatically depend on the
copy constructors of the different listed classes. You must consider ther following restrictoins:
Do NOT attempt to explicitly find the exact type of the objects being copied, do NOT
attempt to find the object type inside the copy constructors and Do NOT use clone().
2. In the driver program, create an array of 15 to 20 objects (must have at least one from each of the
classes), then call the copyFlyingObjects() method to create a copy of the that array.
3. Display the contents of both arrays, then add some comments indicating whether or not the
copying is correct. If not; you need to explain why it has not been successful or as you might
General Guidelines When Writing Programs
• Include the following comments at the top of each class you are writing.
// Part: (include Part Number)
// Written by: (include your name(s) and student ID(s))
• Use JavaDoc to create the documentations of your program. Use appropriate comments when
• Display clear prompts for the user whenever you are expecting the user to enter data from the
• All outputs should be displayed with clear messages and in an easy to read format.
• End your program with a closing message so that the user knows that the program has terminated.
Comp249/Winter 2020 – Assignment 2 Page 4 of 4
Submitting Assignment 2
– For this assignment, you are allowed to work individually, or in a group of a maximum of 2
students (i.e. you and one other student). You and your teammate must however be in the same
section of the course. Groups of more than 2 students = zero mark for all members!
– Only electronic submissions will be accepted. Zip together the source codes.
– Students will have to submit their assignments (one copy per group) using the EAS system
(https://fis.encs.concordia.ca/eas/). Assignments must be submitted in the right folder of the
assignments. Assignments uploaded to an incorrect folder will not be marked and result in a
zero mark. No resubmissions will be allowed.
– Naming convention for zip file: Create one zip file, containing all source files and produced
documentations for your assignment using the following naming convention:
The zip file should be called a#_StudentName_StudentID, where # is the number of the
assignment and StudentName/StudentID is your name and ID number respectively. Use
your “official” name only – no abbreviations or nick names; capitalize the usual “last”
name. Inappropriate submissions will be heavily penalized. For example, for the first
assignment, student 12345678 would submit a zip file named like: a1_MikeSimon_123456.zip. if working in a group, the name should look like: a1_MikeSimon_12345678-AND-Linda-Jackson_98765432.zip.
– Submit only ONE version of an assignment. If more than one version is submitted the first one
will be graded and all others will be disregarded.
– If working in a team, only one of the members can upload the assignment. Do NOT upload the
file for each of the members!
Important: Following your submission, a demo is required (please refer to the courser
outline for full details). The marker will inform you about the demo times. Please notice
that failing to demo your assignment will result in zero mark regardless of your
UML representation of class hierarchy 2 pts
Proper use of packages 1 pt
Correct implementation of the classes 1 pt
Constructors 1 pt
toString() & equals() 1 pt
copyFlyingObjects() and its behaviour 2 pts
Driver program & general correctness of code 2 pts
Total 10 pts