Description
Inheritance (Extends, Super, Overloading, Overriding) and JUnit
In this lab, you will practice how to implement multiple classes using inheritance hierarchy. You
will also implement JUnit tester classes to test and write Javadoc comments for the classes and
methods. You must use the instanceof operator in equals methods to make sure there won’t be any
ClassCastException when you cast objects. Please review the slides 68-79 (Lecture_Inheritance,
posted on Canvas) to write equals method.
Problem 1:
In this inheritance hierarchy, we have three classes, Person, Student, and Instructor. Student and
Instructor classes are the subclasses of the superclass Person. Create a project in Eclipse named
Lab_06.
• Class Person:
Create a class named Person which has the following information (use appropriate type or class
for each instance variable):
• Name, the name of the person.
• Year of birth, the year of birth of the person.
The class should also have the following methods:
• Constructors: Two constructors, one default constructor, which initializes the instances
variables to the default values (strings to null, numbers to zero) and the second,
parameterized constructor, which initializes the instances variables using the received
parameters.
• Accessor and mutator methods for all instance variables.
• public boolean equals(Object obj)
The method returns true if the two persons have the same name and year of birth. False,
otherwise.
Important Note: This is an overridden equals() method.
• public String toString()
The method returns a String representing the person object that includes name and year of
birth. It returns a String like “I am a person whose name is James Bond and was born in
1997”.
• Class Student:
Create a class named Student which is a subclass of Person and has the following information
use appropriate type or class for each instance variable):
• Major, the major of the student.
The class should also have the following methods:
• Constructors: Two constructors, one default constructor, which initializes the instances
variables to the default values (strings to null, numbers to zero) and the second,
parameterized constructor, which initializes the instances variables using the received
parameters.
Important Note: Utilize the super() constructor appropriately. The student constructor
needs to call the super constructor with the appropriate data to initialize the person’s
instance variables.
• Accessor and mutator methods for all instance variables.
• public boolean equals(Object obj)
The method returns true if the two persons have the same name, year of birth, and major.
False, otherwise.
Important Note: This is an overridden equals() method. Use equals() method from the super
class whenever applicable.
• public String toString()
Lab Assignment 06, Object-Oriented Programming, CSE 271, Spring 2020
Department of Computer Science and Engineering, Miami University
Inheritance (Extends, Super, Overloading, Overriding) and JUnit
The method returns a String representing the student object that includes name, year of birth,
and major. It returns a String like “I am a student majoring in Computer Science. I am a
person whose name is James Bond and was born in 1997”.
Important Note: This is an overridden toString() method. Use toString() method from super
class to avoid writing same code again. Call super.toString() to get a string from the super
class.
• Class Instructor:
Create a class named Instructor which is a subclass of Person and has the following information
use appropriate type or class for each instance variable):
• Rank, the rank of the instructor (lecturer, assistant professor, associate professor, professor).
The class should also have the following methods:
• Constructors: Two constructors, one default constructor, which initializes the instances
variables to the default values (strings to null, numbers to zero) and the second,
parameterized constructor, which initializes the instances variables using the received
parameters.
Important Note: Utilize the super() constructor appropriately. The instructor constructor
needs to call the super constructor with the appropriate data to initialize the person’s
instance variables.
• Accessor and mutator methods for all instance variables.
• public boolean equals(Object obj)
The method returns true if the two instructors have the same name, year of birth, and rank.
False, otherwise.
Important Note: This is an overridden equals() method. Use equals() method from the super
class whenever applicable.
• public String toString()
The method returns a String representing the instructor object that includes name, year of
birth, and rank. It returns a String like “I am a lecturer. I am a person whose name is James
Bond and was born in 1997”.
Important Note: This is an overridden toString() method. Use toString() method from super
class to avoid writing same code again. Call super.toString() to get a string from the super
class.
Problem 2:
In this inheritance hierarchy, we have four classes, Person, Employee, Manager, and Executive.
Employee is a subclass of Person, Manager is a subclass of Employee, and Executive is a subclass of
Manager.
• Class Employee:
Create a class named Employee which is a subclass of Person and has the following information
(use appropriate type or class for each instance variable):
• Salary, the salary of the employee (for example, $50,000.00).
The class should also have the following methods:
• Constructors: Two constructors, one default constructor, which initializes the instances
variables to the default values (strings to null, numbers to zero) and the second,
parameterized constructor, which initializes the instances variables using the received
parameters.
Important Note: Utilize the super() constructor appropriately. The student constructor
needs to call the super constructor with the appropriate data to initialize the person’s
instance variables.
Lab Assignment 06, Object-Oriented Programming, CSE 271,
Department of Computer Science and Engineering, Miami University
Inheritance (Extends, Super, Overloading, Overriding) and JUnit
• Accessor and mutator methods for all instance variables.
• public boolean equals(Object obj)
The method returns true if the two persons have the same name, year of birth and salary.
False, otherwise.
Important Note: This is an overridden equals() method. Use equals() method from the super
class whenever applicable.
• public String toString()
The method returns a String representing the person object that includes name, year of birth,
and salary. It returns a String like “I am an employee and have a salary of $50,000.00. I am a
person whose name is James Bond and was born in 1997”.
Important Note: This is an overridden toString() method. Use toString() method from super
class to avoid writing same code again. Call super.toString() to get a string from the super
class.
• Class Manager:
Create a class named Manager which is a subclass of Employee and has the following
information use appropriate type or class for each instance variable):
• Department, the department of the manager.
The class should also have the following methods:
• Constructors: Two constructors, one default constructor, which initializes the instances
variables to the default values (strings to null, numbers to zero) and the second,
parameterized constructor, which initializes the instances variables using the received
parameters.
Important Note: Utilize the super() constructor appropriately. The student constructor
needs to call the super constructor with the appropriate data to initialize the person’s
instance variables.
• Accessor and mutator methods for all instance variables.
• public boolean equals(Object obj)
The method returns true if the two managers have the same name, year of birth, and
department. False, otherwise.
Important Note: This is an overridden equals() method. Use equals() method from the super
class whenever applicable.
• public String toString()
The method returns a String representing the manager object that includes name, year of
birth, and department. It returns a String like “I am a manager of the Human Resource
department. I am an employee and have a salary of $50,000.00. I am a person whose name
is James Bond and was born in 1997”.
Important Note: This is an overridden toString() method. Use toString() method from super
class to avoid writing same code again. Call super.toString() to get a string from the super
class.
• Class Executive:
Create a class named Executive which is a subclass of Manager and has the following
information use appropriate type or class for each instance variable):
• Office location, the office location of the executive (suite 300, room 420).
The class should also have the following methods:
• Constructors: Two constructors, one default constructor, which initializes the instances
variables to the default values (strings to null, numbers to zero) and the second,
parameterized constructor, which initializes the instances variables using the received
parameters.
Lab Assignment 06, Object-Oriented Programming, CSE 271,
Department of Computer Science and Engineering, Miami University
Inheritance (Extends, Super, Overloading, Overriding) and JUnit
Important Note: Utilize the super() constructor appropriately. The student constructor
needs to call the super constructor with the appropriate data to initialize the person’s
instance variables.
• Accessor and mutator methods for all instance variables.
• public boolean equals(Object obj)
The method returns true if the two executives have the same name, year of birth, and office
location. False, otherwise.
Important Note: This is an overridden equals() method. Use equals() method from the super
class whenever applicable.
• public String toString()
The method returns a String representing the instructor object that includes name, year of
birth, and rank. It returns a String like “I am an executive and my office location is room 420.
I am a manager of the Human Resource department. I am an employee and have a salary of
$50,000.00. I am a person whose name is James Bond and was born in 1997”.
Important Note: This is an overridden toString() method. Use toString() method from super
class to avoid writing same code again. Call super.toString() to get a string from the super
class.
Javadoc Style Comments:
You have to make Javadoc style comments for all methods and classes including parameter and
return description. Once you write all the Javadoc style comments generate Javadoc using Eclipse’s
“Generate Javadoc” option from the “project” menu. Include the Javadoc folder “doc” with your code
submission.
Tester Class:
Now write JUnit testers for each of the classes you define. In your Tester classes you have to test all
the methods (constructor, accessor, mutator, equals, toString) of the classes you defined (Person,
Student, Instructor, Employee, Manager, and Executive).
Important Note:
Make sure the file name is correct and code is well commented. No late submission. You will get
zero for late submission.
Submission:
Submit java files and Javadoc folder “doc” to the appropriate submission folder on the Canvas by the
due time. You can zip all the java files and “doc” folder together and submit one zip file.
Lab Assignment 06, Object-Oriented Programming, CSE 271
Department of Computer Science and Engineering, Miami University
Inheritance (Extends, Super, Overloading, Overriding) and JUnit
Grading Rubric:
Person
Declare private fields with appropriate type or class 1
Constructors (each worth 1 points) 2
Accessors and Mutators (each worth 0.5 points) 2
equals() method 3
toString() method 3
Student
Declare private fields with appropriate type or class 1
Constructors (each worth 2 points) 4
Accessors and Mutators (each worth 0.5 points) 1
equals() method 3
toString() method 3
Instructor
Declare private fields with appropriate type or class 1
Constructors (each worth 2 points) 4
Accessors and Mutators (each worth 0.5 points) 1
equals() method 3
toString() method 3
Employee
Declare private fields with appropriate type or class 1
Constructors (each worth 2 points) 4
Accessors and Mutators (each worth 0.5 points) 1
equals() method 3
toString() method 3
Manager
Declare private fields with appropriate type or class 1
Constructors (each worth 2 points) 4
Accessors and Mutators (each worth 0.5 points) 1
equals() method 3
toString() method 3
Executive
Declare private fields with appropriate type or class 1
Constructors (each worth 2 points) 4
Accessors and Mutators (each worth 0.5 points) 1
equals() method 3
toString() method 3
Testing
Test constructors (each worth 0.5 points) 6
Test accessors and mutators (each worth 0.5 points) 7
Test equals and toString methods (each worth 1 points) 12
Javadoc
Javadoc style comments 4
Submitted correct Javadoc files [Only deduction] 0 [-5]
Total 100
