Java

OOP GUIDE / WORK

PERSON SUPERCLASS AND STUDENT & TEACHER SUBCLASSES

Topics

• Extending a superclass
• Creating a subclass
• Calling a superconstructor
• Testing subclass objects for superclass instance variables and methods

TASK – PART 1 – CONSIDER THE PERSON CLASS

Copy the following class to your IDE.

public class Person

{

public String name;

public int yob;

public Person(String n, int yob)

{

name = n;

this.yob = yob;

}

public String toString()

{

return name + " (" + yob + ")";

}

public int getAge()

{

return 2021 - yob; //change 2021 to current year

}

}

TASK – PART 2 – TEST THE PERSON CLASS

Inside a Tester class, insert a main method and do the following:

• Create a Person object that represents you.
  
  
• Use its toString() method to output its state to screen.
  
  
• Output the object’s age to screen.

TASK – PART 3 – THE STUDENT CLASS

Make a new class named Student. Make it extend the Person class.

Here are the specs for the Student class:

INSTANCE VARIABLES

• school
• studentNumber

CONSTRUCTOR

• A constructor that gets four parameters, one for each instance variable. Don’t forget to call the superconstructor.

INSTANCE METHOD(S)

• A toString() method that outputs a string representation of the student.

TASK – PART 4 – TEST THE STUDENT CLASS

Inside the same tester class as in Part 2, do the following:

• Create a Student object with the following values
• Name: Jim Bo
• Year of birth: 2007
• School: Lockerby
• Student number: 123456789
  
  
• Use its toString() method to output its state to screen.
  
  
• Output the object’s age to screen. Notice that this method is inherited from the Person class!

TASK – PART 5 – THE TEACHER CLASS

Make a new class named Teacher. Make it extend the Person class.

Here are the specs for the Teacher class:

INSTANCE VARIABLES

• school
• areaOfSpecialty

CONSTRUCTOR

• A constructor that gets four parameters, one for each instance variable. Don’t forget to call the superconstructor.

INSTANCE METHOD(S)

• A toString() method that outputs a string representation of the teacher. However, you should make use of the Person’s toString method by using super.toString() to build part of your string.

TASK – PART 6 – TEST THE TEACHER CLASS

Inside the same tester class as in Part 2, do the following:

• Create a Teacher object with the following values
• Name: Mr. D.
• Year of birth: 1968
• School: Xavier Academy
• areaOfSpecialty: Social Studies
  
  
• Use its toString() method to output its state to screen.
  
  
• Output the object’s age to screen. Notice that this method is inherited from the Person class!