Library.java

package com.interview.design.questions.onlinereader;

import java.util.Hashtable;

public class Library {

	private Hashtable<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);
	}
}