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Object Oriented Programming

Exercise Part One

Your final project we will be developing an E-commerce application, but we tackle this in phases. For todays class we will look a small part of the E-commerce application.

Let us assume we are selling Books in our E-commerce application. For a book we will store the following attributes.

ISBN Number
Title
Author (assume it is only one author for now)

We will also need a Cart module. During the checkout process we will add Books to our cart and we will want to

Print out details of our cart.
We may also want to calculate the total number of books in our Cart.
And also we may want to calculate the total Amount/cost.

Exercise

Figure out the following (Do not worry about implementation at this stage.)

Classes you need.
Instances variables for each class.
Functions/methods for each class.

Part Two

Implement the Book Class
- Define instance variables.
- Provide a constructor - For now assume the input arguments to be ISBN Number, Title and Author
- Create a method to printBookDetails
Create a new class called - ECommerceStarter with a main method to test our Book class
- Create objects of the Book class.
- Call printBookDetails on objects to print details of the Book class.

Part Three

Let us assume we are going to read book details from a file, and each line in the file has details for a book and the fields are seperate by comma.

ISNB0001, How to program in Java, John Doe, 21.2
ISNB0002, How to program in JavaScript, Sally Smith, 19.2

Let us also assume we can read a line from the file, which is details for a Book, Can you suggest changes to our existing implementation if we need to initialize a Book.

Part Four

Implement a new Book Constructor which takes a String, which is a comma separated list of book attributes. Use the new Constructor in your main class. You can assume that order of fields in the comma separated string is fixed.

public class Book {

    //Instance Variables
    private String ISBN;
    private String title;
    private String author;
    private double cost;

    //Constructor - initialize instance variables
    public Book(String isbnInput, String titleInput, String authorInput, double costInput) {
        this.ISBN = isbnInput;
        this.title = titleInput;
        this.author = authorInput;
        this.cost = costInput;
    }

    public Book(String commaSeperatedLine) {
        //your implementation
        // look at split method in String,
        // initialize instance variable
    }

    public void printBookDetails() {
        System.out.println("ISBN Number :"+ISBN + " title : "+title+ " author: "+ this.author+ " cost:"+cost);
    }


}

public class ECommerceSimple {

    public static void main(String[] args) {
        Book javaBook = new Book("ISNB0001", "How to program in Java", "John Doe", 24.5);
        javaBook.printBookDetails();

        Book cPlusPlusBook = new Book("ISNB0002", "How to program in c Plus Plus", "Sally Smith", 19.9);
        cPlusPlusBook.printBookDetails();

       // Call your new constructor here
    }
}

Static variable

This is a variable per Class, Not a variable per Object. A good example would be count of books.

Part Six

Implement a Cart Class

Week Seven