Question: /* Design the data structures for an online book reader system. */ //a basic online reading system: // 1. user membership createion and extension //
/*
Design the data structures for an online book reader system.
*/
//a basic online reading system:
// 1. user membership createion and extension
// 2. searching the database of bookds
// 3. reading a book
// 4. only one active user at a time
// 5. only one active book by this user
//class User, Book, and Library
//represents the body of the program, implement the class such that it stores informationabout all the books, deals with user management, and refreshes the display
public class OnlineReaderSystem{
private Library library;
private UserManager userManager;
private Display display;
private Book activeBook;
private User activeUser;
public OnlineReaderSystem(){
userManager = new UserManager();
library = new Library();
display = new Display();
}
public Library getLibrary(){
return library;
}
public UserManager getUserManager(){
return userManager;
}
public Display getDisplay(){
return display;
}
public Book getActiveBook(){
return activeBook;
}
public User getActiveUser(){
return activeUser;
}
public void setActiveBook(Book book){
display.displayBook(book);
activeBook = book;
}
public void setActiveUser(User user){
display.displayUser(user);
activeUser = user;
}
}
//manage the book
public class Library{
private HashTable
public Book addBook(int id, String details){
if (books.containsKey(id)){
return null;
}
Book book = new Book(id, details);
books.put(id, book);
return book;
}
public boolean remove(Book b){
return remove(b.getID());
}
public boolean remove(int id){
if (!book.containsKey(id)){
return false;
}
books.remove(id);
return true;
}
public Book find(int id){
return books.get(id);
}
}
//hold data and provide little true functionality
public class Book{
private int bookId;
private String details;
public Book(int id, String det){
bookId = id;
details = det;
}
public void update(){
}
public int getID(){
return bookId;
}
public void setID(int id){
bookId = id;
}
public String getDetails(){
return details;
}
public void setDetails(String details){
this.details = details;
}
}
//manage the user
public class UserManager{
private HashTable
public User addUser(int id, String details, int accountType){
if (users.containsKey(id)){
return null;
}
User user = new User(id, details, accountType);
users.put(id, user);
return user;
}
public boolean remove(User u){
return remove(u.getID());
}
public boolean remove(int id){
if (!users.containsKey(id))
return false;
users.remove(id);
return true;
}
public User find(int id){
return users.get(id);
}
}
public class User{
private int userId;
private String details;
private int accountType;
public void renewMembership(){
}
public User(int id, String details, int accountType){
userId = id;
this.details = details;
this.accountType = accountType;
}
public int getID(){
return userId;
}
public void setID(int id){
userId = id;
}
public String getDetails(){
return details;
}
public void setDetails(String details){
this.details = details;
}
public int getAccountType(){
return accountType;
}
public void setAccountType(int accountType){
this.accountType = accountType;
}
}
public class Display{
private Book activeBook;
private User activeUser;
private int pageNumber = 0;
public void displayUser(User user){
activeUser = user;
refreshUsername();
}
public void displayBook(Book book){
activeBook = book;
pageNumber = 0;
refreshTitle();
refreshDetails();
refreshPage();
}
public void refreshUsername(){
}
public void refreshTitle(){
}
public void refreshPage(){
}
public void refreshDetails(){
}
public void turnPageForward(){
pageNumber++;
refreshPage();
}
public void turnPageBackward(){
pageNumber--;
refreshPage();
}
}
This program is not working Can anybody please help with the good and easy solution for a beginner in JAVA to understand
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