package com.study.demo3; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; public class Library { private Map books; public Library() { this.books = new HashMap<>(); } public void addBook(Book b) { String isbn = b.getIsbn(); if (books.containsKey(isbn)) { System.out.println("The book already exists, adding it failed."); } else { books.put(isbn, b); System.out.println("Book added successfully: " + b.getTitle()); } } public List searchAvailableBooks() { List availableBooks = new ArrayList<>(); for (Book book : books.values()) { if (book.isAvailable()) { availableBooks.add(book); } } return availableBooks; } }