Question

Q1. Write an application that performs each of the following tasks:

a) Specify that class “Pieceworker” inherits from class Employee.

b) Create instance variables “Firstname” and “ID” in superclass and a toString to display.

c) Add “branch” and toString in PieceWorker.

d) Show overriding to display the variables of the subclass.

Q2 Draw an inheritance hierarchy for students at a university.

• Use Student as the superclass of the hierarchy, and then extend Student with classes Undergraduate Student and Graduate Student.
• Continue to extend the hierarchy as deep (i.e., as many levels) as possible. For example, freshman, sophomore, Junior and Senior might extend undergraduate Student, and Doctoral Student and Masters Student might be subclasses of graduate Student.
• After drawing the hierarchy, discuss the relationships that exist between the classes.
• Write a program that illustrates the above idea of hierarchy.

Answer 1

Q1

class Employee
{
   String Firstname = "ABC";
   int ID = 123; //values hadcoded here, can be used through constructor as well.

void show()
   {
       System.out.println(Firstname + ID);
   }
   @Override
   public String toString() {
       return "Employee [Firstname=" + Firstname + ", ID=" + ID + "]";
   }
}

class PieceWorker extends Employee
{
   String branch = "CSE";
   Employee emp = new Employee();
  

    @Override
   void show()
   {

//first way of overriding, and showing superclass variables here. We can reassign the value of one of the variables //of superclass as well, for eg String Firstname="DEF";
       System.out.println(Firstname + ID + branch);
   }

   @Override //overriding and using the employee variables in the subclass
   public String toString() {
       return "PieceWorker [branch=" + branch + "]" + "Employee [Firstname=" + emp.Firstname + ", ID=" + emp.ID + "]";
   }  
}

public class Driver_Class
{

public static void main(String[] args)
{
   PieceWorker pw = new PieceWorker();
   System.out.println(pw.varValues());
}

}

Q2

//Please feel free to add more variables wherever necessary, a basic template implementation has been shown //hereunder with basic variables relevant to each subclass. The hierarchy can be drawn as a simple multiple //inheritance, the relation being that Student is the super class to both UG and Graduate class, and has the basic //information of a student, building on top of which each child class is adding more relevant data. Please feel free to //add in comments if any extra information is needed.

class Student //superclass
{
   String Name, Address;
   int phone, zip;
}

class Undergraduate_Student extends Student
{
   String course; //all variables of Student class are already inherited, hence we only build on top of that
   int duration;
   double current_CGPA;
}

class Graduate_Student extends Student
{
   double grad_CGPA;
   String grad_College;
  
}

class Freshman extends Undergraduate_Student
{
   String school_passed_from;
}

class Sophomore extends Undergraduate_Student
{
   double CGPA_first_year;
}

class Junior extends Undergraduate_Student
{
   String[] junior_Subjects;
   String junior_College_Name;
}

class Senior extends Undergraduate_Student
{
   double current_CGPA;
   String[] senior_subjects;
   String senior_College_Name;
}

class Masters_Student extends Graduate_Student
{
   String masters_course;
   double masters_Current_CGPA;
}

class Doctorals_Student extends Graduate_Student
{
   String[] doctoral_theme;
   double post_grad_CGPA;
   String PG_College;
}

public class Driver_Class
{

public static void main(String[] args)
{
   Doctorals_Student doct_stu - new Doctorals_Student ();

//can instantiate further, and if required can use constructors to load data from the driver class
}

}

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