this library application

package careercup.test.amazon;

import java.util.Collection;

/**
 * 
    design a library for borrowing books and renewing.

    1. On Borrowing

         Verify user validations .
         perform borrowing 

    2. On renewal

        verify user validations
        perform renewal .


 * @author dileep
 *
 */
public class LibraryForBooksBorrowing {

    /**
     * 
     */
    public void onBorrowing(Book book,User user){
        // Do some validations
        user.borrowBook(book);
    }

    /**
     * 
     * @param b
     * @param user
     */
    public void onRenewal(Book b, User user){
        user.renewalBook(b);
    }

    /**
     * 
     * @author dileep
     *
     */
    private static class User{
        private final long userId=0;

        private Collection<Book> borrowedBooks;

        public void borrowBook(Book b){
            borrowedBooks.add(b);
        }

        public void renewalBook(Book b){
            if(borrowedBooks.contains(b)){
                // perform renewal operation .
            }
        }

        public boolean isRenewalExceeded() {
            // TODO Auto-generated method stub
            return false;
        }

    }

    /**
     * 
     * @author dileep
     *
     */
    private static class Book{
        private final long UNIQUE_CODE= 0;
    }

    /**
     * 
     * 1.Adds new Book backed by a store..
     * 2. Deletes ...
     * 
     * @author dileep
     *
     */
    private static class BookStore{

        private Collection<Book> books;
    }

    /**
     * performs User level operations .
     * 1. Adds a new User 
     * 2. Deleted existing User
     * 3. performs appropriate actions when lending date is reached ...
     *         a) sends e-mail 
     *     b) calculates total fine .
     */
    private static class Users{

        private Collection<User> allMembers;

        /**
         * iterate over all users , do checks on renewal..
         */
        public void doThisEveryDay(){

            for(User user:allMembers){

                if(user.isRenewalExceeded()){
                    //Send e-mail 
                    // Calculate fine 
                }
            }
        }

    }
}