Question

Java iteration method, I need a method which iterates through a collection of books and adjusts the price of all books published between the given parameters to give a 20% discount off the price of each book published between the given years?

Book class

public class Book
{

    private String title;
    private String author;
    private int yearPublished;
    private double bookPriceInCAD;


    public Book(String inputTitle, String inputAuthor, int inputYearPublished, double inputBookPriceInCAD){
     setTitle(inputTitle);
     setAuthor(inputAuthor);
     setYearPublished(inputYearPublished);
     setBookPriceInCAD(inputBookPriceInCAD);
    }

    public String getTitle(){
        return title;
    }

    public String getAuthor(){
        return author;
    }

    public int getYearPublished(){
        return yearPublished;
    }

    public double getBookPriceInCAD(){
        return bookPriceInCAD;
    }

    public void setTitle(String title){
        if(title !=null && !title.isEmpty()){
            this.title = title;
        } else if(title == null){
            throw new IllegalArgumentException("title cannot be null");
        } else if(title.isEmpty()){
            throw new IllegalArgumentException("title cannot be an empty String");
        }
     }

     public void setAuthor(String author){
        if(author !=null && !author.isEmpty()){
            this.author = author;
        } else if(author == null){
            throw new IllegalArgumentException("author cannot be null");
        } else if(author.isEmpty()){
            throw new IllegalArgumentException("author cannot be an empty String");
        }
    }

    public void setYearPublished(int yearPublished){
        if(yearPublished > 0){
            this.yearPublished = yearPublished;
        } else {
            throw new IllegalArgumentException("year published cannot be negative");
        }
      }

    public void setBookPriceInCAD(double bookPriceInCAD){
        if(bookPriceInCAD > 0){
            this.bookPriceInCAD = bookPriceInCAD;
        } else {
            throw new IllegalArgumentException("book price in CAD cannot be negative");
        }
    }

BookStore Class

import java.util.ArrayList;
import java.util.Iterator;
public class BookStore
{
  

    private ArrayList<Book> bookList;
    private String businessName;
  

    public BookStore()
    {
        // initialise instance variables
        bookList = new ArrayList<Book>();
        businessName = "Book Store";
      
    }

    public BookStore(String inputBusinessName){
        setBusinessName(inputBusinessName);
        bookList = new ArrayList<Book>();
     }


    public void setBusinessName(String businessName){
        if(businessName !=null && !businessName.isEmpty()){
            this.businessName = businessName;
        } else if(businessName == null){
            throw new IllegalArgumentException("business Name cannot be null");
        } else if(businessName.isEmpty()){
            throw new IllegalArgumentException("business Name cannot be an empty String");
        }
     }

    public String getBusinessName(){
        return businessName;
    }

    public ArrayList<Book> getBookList(){
        return bookList;
    }

    public void addBook(Book book){
      if(book!=null){
          bookList.add(book);
    }
    }

    public void getBook(int index) {
    if((index >= 0) && (index <= bookList.size())) {
        Book oneBook = bookList.get(index);              
        oneBook.displayDetails();
    }
    else{
        System.out.println("Invalid index position");
    }
    }

    public void searchBook(String title){
        for(Book b: bookList){
         String bookTitle = b.getTitle();
        if(bookTitle.equalsIgnoreCase(title)){
            b.displayDetails();
        } else{
            System.out.println("book not found");
    }
    }
    }

    public void displayBookDetails(){
        for(Book oneBook: bookList){
            oneBook.displayDetails();
          
      }
    }
  

    public static void main(String[] args){
        BookStore list = new BookStore();
        Book b1 = new Book("hello world","steven segal",2005,20.00);
        Book b2 = new Book("goodbye world","Jeff country", 208,10.00);
        Book b3 = new Book("no world","Bill Nye",202,30.00);
        list.addBook(b1);
        list.addBook(b2);
        list.addBook(b3);
        list.getBook(4);
        list.getBook(2);

        list.displayBookDetails();
    }
  
       public int donateBook(int yearPublished){
        Iterator<Book> iter = bookList.iterator();
        int count = 0;
        while(iter.hasNext()){
            Book aBook = iter.next();
          
            if(yearPublished <= aBook.getYearPublished()){
                iter.remove();
                count++;
            }
        }
        return count;
    }
    public void applyDiscountToBook(int beginYear, int endYear){
    }
   

Answer 1

Hi,

Please find the apply discount method:

Steps:

• Iterate each book in the collection.
• Get the Year of Publish.
• Check if its in between start and end year.
• Get the book price.
• Apply the 20% discount.
• Set the discounted price to the book object.

Java Method:

public void applyDiscountToBook(int beginYear, int endYear){
       Iterator<Book> iter = bookList.iterator();
       while(iter.hasNext()){
            Book aBook = iter.next();
        
            if(beginYear <= aBook.getYearPublished() && endYear >= aBook.getYearPublished()){
               double beforeDiscountPrice = aBook.getBookPriceInCAD(); //getBookPrice
               double afterDiscountPrice= beforeDiscountPrice * 0.8 ;//20% off
               aBook.setBookPriceInCAD(afterDiscountPrice);//set discounted price
            }
        }
    }

Screenshot:

Hope this helps.