LibraryManagementSystem.java

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

// 1. Book Class
class Book {
    private String title;
    private String author;
    private String isbn;
    private boolean isAvailable;

    public Book(String title, String author, String isbn) {
        this.title = title;
        this.author = author;
        this.isbn = isbn;
        this.isAvailable = true; // Books are available by default when added
    }

    public String getTitle() { return title; }
    public String getAuthor() { return author; }
    public String getIsbn() { return isbn; }
    public boolean isAvailable() { return isAvailable; }

    public void borrowBook() {
        if (isAvailable) {
            isAvailable = false;
        }
    }

    public void returnBook() {
        isAvailable = true;
    }

    public void displayBookInfo() {
        System.out.println("Title: " + title + " | Author: " + author + 
                           " | ISBN: " + isbn + " | Available: " + (isAvailable ? "Yes" : "No"));
    }
}

// 2. Member Class
class Member {
    private String name;
    private String memberId;
    private List<Book> borrowedBooks;

    public Member(String name, String memberId) {
        this.name = name;
        this.memberId = memberId;
        this.borrowedBooks = new ArrayList<>();
    }

    public String getName() { return name; }
    public String getMemberId() { return memberId; }

    public void borrowBook(Book book) {
        borrowedBooks.add(book);
        book.borrowBook();
        System.out.println(name + " successfully borrowed: " + book.getTitle());
    }

    public void returnBook(Book book) {
        if (borrowedBooks.remove(book)) {
            book.returnBook();
            System.out.println(name + " successfully returned: " + book.getTitle());
        } else {
            System.out.println("This book was not borrowed by this member.");
        }
    }

    public void displayMemberInfo() {
        System.out.println("Member ID: " + memberId + " | Name: " + name + 
                           " | Books Borrowed: " + borrowedBooks.size());
    }
}

// 3. Library Class
class Library {
    private List<Book> books;
    private List<Member> members;

    public Library() {
        this.books = new ArrayList<>();
        this.members = new ArrayList<>();
    }

    public void addBook(Book book) {
        books.add(book);
        System.out.println("Book added to the library successfully!");
    }

    public void addMember(Member member) {
        members.add(member);
        System.out.println("Member registered successfully!");
    }

    public Member searchMemberById(String memberId) {
        for (Member member : members) {
            if (member.getMemberId().equals(memberId)) {
                return member;
            }
        }
        return null;
    }

    public Book searchBookByTitle(String title) {
        for (Book book : books) {
            if (book.getTitle().equalsIgnoreCase(title)) {
                return book;
            }
        }
        return null;
    }

    // Borrow a book (Matches your screenshot logic)
    public void borrowBook(String memberId, String bookTitle) {
        Member member = searchMemberById(memberId);
        Book book = searchBookByTitle(bookTitle);

        if (member != null && book != null && book.isAvailable()) {
            member.borrowBook(book);
        } else if (book != null && !book.isAvailable()) {
            System.out.println("The book is currently not available.");
        } else {
            System.out.println("Member or book not found.");
        }
    }

    // Return a book (Matches your screenshot logic)
    public void returnBook(String memberId, String bookTitle) {
        Member member = searchMemberById(memberId);
        Book book = searchBookByTitle(bookTitle);

        if (member != null && book != null && !book.isAvailable()) {
            member.returnBook(book);
        } else {
            System.out.println("Member or book not found, or the book was not borrowed.");
        }
    }

    // Display all books
    public void displayBooks() {
        if (books.isEmpty()) {
            System.out.println("No books in the library.");
            return;
        }
        for (Book book : books) {
            book.displayBookInfo();
        }
    }

    // Display all members
    public void displayMembers() {
        if (members.isEmpty()) {
            System.out.println("No members registered.");
            return;
        }
        for (Member member : members) {
            member.displayMemberInfo();
        }
    }
}

// Main Class (Driver Program)
public class LibraryManagementSystem {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        Library library = new Library();5

        // Initial Instructions for the user
        System.out.println("Welcome to the Library Management System");
        boolean exit = false;

        while (!exit) {
            System.out.println("\nChoose an option:");
            System.out.println("1. Add a Book");
            System.out.println("2. Register a Member");
            System.out.println("3. Borrow a Book");
            System.out.println("4. Return a Book");
            System.out.println("5. Display All Books");
            System.out.println("6. Display All Members");
            System.out.println("7. Exit\n");
            
            System.out.print("Enter your choice: ");
            
            // Check if the input is an integer to prevent crash on wrong input type
            if (!scanner.hasNextInt()) {
                System.out.println("Invalid input. Please enter a number.");
                scanner.next(); // Consume the invalid input
                continue;
            }
            
            int choice = scanner.nextInt();
            scanner.nextLine(); // Consume newline character

            switch (choice) {
                case 1: // Add a Book
                    System.out.println("Enter Book Title:");
                    String title = scanner.nextLine();
                    System.out.println("Enter Book Author:");
                    String author = scanner.nextLine();
                    System.out.println("Enter Book ISBN:");
                    String isbn = scanner.nextLine();
                    library.addBook(new Book(title, author, isbn));
                    break;

                case 2: // Register a Member
                    System.out.println("Enter Member Name:");
                    String name = scanner.nextLine();
                    System.out.println("Enter Member ID:");
                    String memberId = scanner.nextLine();
                    library.addMember(new Member(name, memberId));
                    break;

                case 3: // Borrow a Book
                    System.out.println("Enter Member ID:");
                    String memberToBorrow = scanner.nextLine();
                    System.out.println("Enter Book Title to Borrow:");
                    String bookToBorrow = scanner.nextLine();
                    library.borrowBook(memberToBorrow, bookToBorrow);
                    break;

                case 4: // Return a Book
                    System.out.println("Enter Member ID:");
                    String memberToReturn = scanner.nextLine();
                    System.out.println("Enter Book Title to Return:");
                    String bookToReturn = scanner.nextLine();
                    library.returnBook(memberToReturn, bookToReturn);
                    break;

                case 5: // Display All Books
                    System.out.println("\n--- Library Books ---");
                    library.displayBooks();
                    break;

                case 6: // Display All Members
                    System.out.println("\n--- Registered Members ---");
                    library.displayMembers();
                    break;

                case 7: // Exit
                    exit = true;
                    System.out.println("Exiting the Library Management System.");
                    break;

                default:
                    System.out.println("Invalid choice. Please select a valid option.");
            }
        }
        scanner.close();
    }
}