Question

Choose any entity of your choice to represent a superclass. It must not be any of the following: - Human, Student, Vehicle, Person, Car, Animal, Book

• Create a class for your entity with the following: - 3 instance variables - 3 instance methods - 2 of the instance methods must show overloading - A default constructor - A parameterized constructor that initializes all instance variables - Getters and setters for the instance variables - Method to print all the details for the class objects with captions for the data.

• Create 2 subclasses for the superclass • Each subclass must have the following: - 2 instance variables - A constructor that first initializes its object variables using the superclass constructor, then initializes the rest. - Getters and setters - A method that overrides the print method in the superclass

• Create a test class and test the print methods in all the classes. java language.

Answer 1

Answer :

import java.io.*;
import java.lang.*;

class Book
{
//instance variables
String name;
String author_name;
double price;
  
//default constructor
Book()
{
System.out.println("Default constructor called");
}
  
//parameterized constructor to initialize all instance variables
public Book(String name, String author_name, double price)
{
this.name=name;
this.author_name=author_name;
this.price=price;
}
  
//instance methods
public void story_book(String genre)   
{
System.out.println("This is "+genre+" type story book");
}
  
public void story_book(String genre, int upper_age_limit) //method overloading
{
System.out.println("This is "+genre+" type story book for upto "+upper_age_limit+" years");
}
  
public void sub_book(String sub_name)
{
System.out.println("This is "+sub_name+" subject book");
}
  
// Getters and Setters
// Returns the name of this book
public String getName() {
return name;
}

// Returns the name of the author of this book
public String getAuthor() {
return author_name;
}
  
// Returns the price of this book
public double getPrice() {
return price;
}
  
// Sets the price of this book
public void setPrice(double price) {
this.price = price;
}
  
}

class TestBook
{
public static void main (String[] args)
{
//Test Book's constructor
Book book1 = new Book("The Secret Seven","Enid Blyton",27.72);
  
//Test setters and getters
System.out.println("Book's name is: "+book1.getName());
System.out.println("Book author's name is: "+book1.getAuthor());
System.out.println("Book's price is: "+book1.getPrice()+" USD");
book1.setPrice(25.42);
System.out.println("Now, the book's price is: "+book1.getPrice()+" USD");
  
//Test method overloading of instance methods
book1.story_book("Children detective");
book1.story_book("Children detective",18);
  
}
}

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