Library.java

    import java.util.*;

public class Library {
    private List<Book> books = new ArrayList<>();
    private Map<Book, User> issuedBooks = new HashMap<>();

    public void addBook(Book book) {
        books.add(book);
    }

    public boolean issueBook(Book book, User user) {
        if (books.contains(book) && !book.isIssued()) {
            book.issue();
            issuedBooks.put(book, user);
            return true;
        }
        return false;
    }

    public boolean returnBook(Book book) {
        if (book.isIssued() && issuedBooks.containsKey(book)) {
            book.returnBook();
            issuedBooks.remove(book);
            return true;
        }
        return false;
    }

    public List<Book> getAvailableBooks() {
        List<Book> available = new ArrayList<>();
        for (Book book : books) {
            if (!book.isIssued()) {
                available.add(book);
            }
        }
        return available;
    }

    public void showIssuedBooks() {
        if (issuedBooks.isEmpty()) {
            System.out.println("No books are currently issued.");
            return;
        }
        System.out.println("Issued Books:");
        for (Map.Entry<Book, User> entry : issuedBooks.entrySet()) {
            System.out.println(entry.getKey().getTitle() + " → issued to " + entry.getValue().getName());
        }
    }
}