Question

1. Create an Item class, which is the abstract super class of all Items.          

1. Item class includes an attribute, description of type String for every item.

[for eg. Book]                                                            

2. A constructor to initialize its data member of Item class.              
3. Override toString() method to return details about the Item class.

2. Create the ExtraCharge interface with the following details.                      

1. Declare a constant RATE with value 0.25  
2. Declare a method called calculateExtraCharge(), which returns a double value.

3. Create the Book class that extends Item and implements ExtraCharge.     
   1. Book class must include three attributes, title of the book, author of the book and price of book.          [For eg. Java Programming, Joyce, 300]    
   2. Define a constructor that takes appropriate parameters so as to initialize data members of book as well as Item class.           
   3. Implement the ExtraCharge interface method.

[Note: When you override calculateExtraCharge() method, it will return extra charge as per the rate defined [0.25] of book price]

3. 4. Override toString() method to return details about the Book class which also includes the details of super class.                                
4. Create ItemTester class to test your application.                  

1. Now create an object of Book class named it myBook and invoke appropriate methods to store book details.

[All the data must be entered by the user. Use do-while loop to let user enter correct data in case wrong data is entered. Mainly user enter wrong price.].                                                           

2. List all myBookdetails by invoking appropriate methods.

3. Use concept of method overloading and overload method methods.

Answer 1

CODE IN JAVA:

Item.java file:

public abstract class Item {
   String description ;

   public Item(String description) {
      
       this.description = description;
   }

   public String toString() {
       return "Item [description=" + description + "]";
   }
  
}

ExtraCharge.java file:

public interface ExtraCharge {
   final double RATE = 0.25 ;
   double calculateExtraCharge();
}

Book.java file:

public class Book extends Item implements ExtraCharge{
   String title ;
   String author ;
   double price ;
   public Book(String description, String title, String author, double price) {
       super(description);
       this.title = title;
       this.author = author;
       this.price = price;
   }
   public double calculateExtraCharge() {
       return price * RATE ;
   }
  
   public String toString() {
       return "description : " + description + ", title=" + title + ", author=" + author + ", price=" + price ;
   }
  
  
  
}

ItemTester.java file:

import java.util.Scanner ;
public class ItemTester {

   public static void main(String[] args) {
       Scanner sc = new Scanner(System.in);
       String description, title, author ;
       double price ;
       System.out.print("Enter the description : ");
       description = sc.nextLine();
       System.out.print("Enter the title : ");
       title = sc.nextLine();
       System.out.print("Enter the author : ");
       author = sc.nextLine();
       System.out.print("Enter the price : ");
       price = sc.nextDouble();
      
       Book myBook = new Book(description, title, author, price);
       System.out.println("Extra charge : " + myBook.calculateExtraCharge());
       System.out.println(myBook);

   }

}

OUTPUT:

@ Console X <terminated > Item Tester (Java Application) C:\Program Files\ava jdk-13.0.1\bin\javaw.exe (24-Apr-2020, 1:57:32 am) Enter the description : Book Enter the title : Fountain Head Enter the author : Ayan rand Enter the price : 300 Extra charge : 75.0 description : Book, title=Fountain Head, author=Ayan rand, price=300.0