package Q7_05_Online_Book_Reader; import java.util.HashMap; public class Library { private HashMap<Integer, Book> books; 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 (!books.containsKey(id)) { return false; } books.remove(id); return true; } public Book find(int id){ return books.get(id); } }