Library Management System in Java

Overview

A comprehensive Library Management System that handles books, members, borrowing, returns, and administrative functions with proper data persistence and user interfaces.

System Architecture

1. Core Domain Models

// Base Entity class import java.io.Serializable; import java.time.LocalDateTime; import java.util.Objects; public abstract class BaseEntity<ID> implements Serializable { private ID id; private LocalDateTime createdAt; private LocalDateTime updatedAt; public BaseEntity() { this.createdAt = LocalDateTime.now(); this.updatedAt = LocalDateTime.now(); } // Getters and setters public ID getId() { return id; } public void setId(ID id) { this.id = id; } public LocalDateTime getCreatedAt() { return createdAt; } public void setCreatedAt(LocalDateTime createdAt) { this.createdAt = createdAt; } public LocalDateTime getUpdatedAt() { return updatedAt; } public void setUpdatedAt(LocalDateTime updatedAt) { this.updatedAt = updatedAt; } @Override public boolean equals(Object o) { if (this == o) return true; if (o == null || getClass() != o.getClass()) return false; BaseEntity<?> that = (BaseEntity<?>) o; return Objects.equals(id, that.id); } @Override public int hashCode() { return Objects.hash(id); } } // Book entity import java.time.Year; import java.util.ArrayList; import java.util.List; public class Book extends BaseEntity<String> { private String isbn; private String title; private String author; private String publisher; private Year publicationYear; private String genre; private int totalCopies; private int availableCopies; private List<BookCopy> copies; public Book() { this.copies = new ArrayList<>(); } public Book(String isbn, String title, String author, String publisher, Year publicationYear, String genre, int totalCopies) { this(); this.isbn = isbn; this.title = title; this.author = author; this.publisher = publisher; this.publicationYear = publicationYear; this.genre = genre; this.totalCopies = totalCopies; this.availableCopies = totalCopies; generateCopies(); } private void generateCopies() { for (int i = 1; i <= totalCopies; i++) { copies.add(new BookCopy(this, i)); } } // Getters and setters public String getIsbn() { return isbn; } public void setIsbn(String isbn) { this.isbn = isbn; } public String getTitle() { return title; } public void setTitle(String title) { this.title = title; } public String getAuthor() { return author; } public void setAuthor(String author) { this.author = author; } public String getPublisher() { return publisher; } public void setPublisher(String publisher) { this.publisher = publisher; } public Year getPublicationYear() { return publicationYear; } public void setPublicationYear(Year publicationYear) { this.publicationYear = publicationYear; } public String getGenre() { return genre; } public void setGenre(String genre) { this.genre = genre; } public int getTotalCopies() { return totalCopies; } public void setTotalCopies(int totalCopies) { this.totalCopies = totalCopies; updateAvailableCopies(); } public int getAvailableCopies() { return availableCopies; } public void setAvailableCopies(int availableCopies) { this.availableCopies = availableCopies; } public List<BookCopy> getCopies() { return copies; } public void setCopies(List<BookCopy> copies) { this.copies = copies; } public void updateAvailableCopies() { this.availableCopies = (int) copies.stream() .filter(BookCopy::isAvailable) .count(); } public boolean isAvailable() { return availableCopies > 0; } @Override public String toString() { return String.format("Book{isbn='%s', title='%s', author='%s', available=%d/%d}", isbn, title, author, availableCopies, totalCopies); } } // Book Copy entity public class BookCopy extends BaseEntity<Long> { private Book book; private int copyNumber; private boolean available; private String condition; // NEW, GOOD, FAIR, POOR private String location; // Shelf location public BookCopy() { this.available = true; this.condition = "NEW"; } public BookCopy(Book book, int copyNumber) { this(); this.book = book; this.copyNumber = copyNumber; } // Getters and setters public Book getBook() { return book; } public void setBook(Book book) { this.book = book; } public int getCopyNumber() { return copyNumber; } public void setCopyNumber(int copyNumber) { this.copyNumber = copyNumber; } public boolean isAvailable() { return available; } public void setAvailable(boolean available) { this.available = available; } public String getCondition() { return condition; } public void setCondition(String condition) { this.condition = condition; } public String getLocation() { return location; } public void setLocation(String location) { this.location = location; } public String getUniqueId() { return book.getIsbn() + "-" + copyNumber; } @Override public String toString() { return String.format("BookCopy{book='%s', copyNumber=%d, available=%s}", book.getTitle(), copyNumber, available); } } // Member entity import java.time.LocalDate; import java.util.ArrayList; import java.util.List; public class Member extends BaseEntity<Long> { private String memberId; private String firstName; private String lastName; private String email; private String phone; private LocalDate joinDate; private MembershipType membershipType; private int maxBooksAllowed; private double outstandingFines; private List<BorrowRecord> borrowHistory; public enum MembershipType { STUDENT(5, 14), FACULTY(10, 30), STAFF(5, 21), PREMIUM(15, 45); private final int maxBooks; private final int loanPeriodDays; MembershipType(int maxBooks, int loanPeriodDays) { this.maxBooks = maxBooks; this.loanPeriodDays = loanPeriodDays; } public int getMaxBooks() { return maxBooks; } public int getLoanPeriodDays() { return loanPeriodDays; } } public Member() { this.borrowHistory = new ArrayList<>(); this.joinDate = LocalDate.now(); this.outstandingFines = 0.0; } public Member(String memberId, String firstName, String lastName, String email, String phone, MembershipType membershipType) { this(); this.memberId = memberId; this.firstName = firstName; this.lastName = lastName; this.email = email; this.phone = phone; this.membershipType = membershipType; this.maxBooksAllowed = membershipType.getMaxBooks(); } // Getters and setters public String getMemberId() { return memberId; } public void setMemberId(String memberId) { this.memberId = memberId; } public String getFirstName() { return firstName; } public void setFirstName(String firstName) { this.firstName = firstName; } public String getLastName() { return lastName; } public void setLastName(String lastName) { this.lastName = lastName; } public String getFullName() { return firstName + " " + lastName; } public String getEmail() { return email; } public void setEmail(String email) { this.email = email; } public String getPhone() { return phone; } public void setPhone(String phone) { this.phone = phone; } public LocalDate getJoinDate() { return joinDate; } public void setJoinDate(LocalDate joinDate) { this.joinDate = joinDate; } public MembershipType getMembershipType() { return membershipType; } public void setMembershipType(MembershipType membershipType) { this.membershipType = membershipType; this.maxBooksAllowed = membershipType.getMaxBooks(); } public int getMaxBooksAllowed() { return maxBooksAllowed; } public void setMaxBooksAllowed(int maxBooksAllowed) { this.maxBooksAllowed = maxBooksAllowed; } public double getOutstandingFines() { return outstandingFines; } public void setOutstandingFines(double outstandingFines) { this.outstandingFines = outstandingFines; } public List<BorrowRecord> getBorrowHistory() { return borrowHistory; } public void setBorrowHistory(List<BorrowRecord> borrowHistory) { this.borrowHistory = borrowHistory; } public int getCurrentlyBorrowedCount() { return (int) borrowHistory.stream() .filter(record -> record.getReturnDate() == null) .count(); } public boolean canBorrowMoreBooks() { return getCurrentlyBorrowedCount() < maxBooksAllowed && outstandingFines == 0; } public void addFine(double amount) { this.outstandingFines += amount; } public void payFine(double amount) { this.outstandingFines = Math.max(0, this.outstandingFines - amount); } @Override public String toString() { return String.format("Member{id='%s', name='%s %s', type=%s, fines=$%.2f}", memberId, firstName, lastName, membershipType, outstandingFines); } } // Borrow Record entity import java.time.LocalDate; public class BorrowRecord extends BaseEntity<Long> { private Member member; private BookCopy bookCopy; private LocalDate borrowDate; private LocalDate dueDate; private LocalDate returnDate; private double fineAmount; private String status; // ACTIVE, RETURNED, OVERDUE public BorrowRecord() { this.borrowDate = LocalDate.now(); this.status = "ACTIVE"; } public BorrowRecord(Member member, BookCopy bookCopy) { this(); this.member = member; this.bookCopy = bookCopy; this.dueDate = borrowDate.plusDays(member.getMembershipType().getLoanPeriodDays()); } // Getters and setters public Member getMember() { return member; } public void setMember(Member member) { this.member = member; } public BookCopy getBookCopy() { return bookCopy; } public void setBookCopy(BookCopy bookCopy) { this.bookCopy = bookCopy; } public LocalDate getBorrowDate() { return borrowDate; } public void setBorrowDate(LocalDate borrowDate) { this.borrowDate = borrowDate; } public LocalDate getDueDate() { return dueDate; } public void setDueDate(LocalDate dueDate) { this.dueDate = dueDate; } public LocalDate getReturnDate() { return returnDate; } public void setReturnDate(LocalDate returnDate) { this.returnDate = returnDate; } public double getFineAmount() { return fineAmount; } public void setFineAmount(double fineAmount) { this.fineAmount = fineAmount; } public String getStatus() { return status; } public void setStatus(String status) { this.status = status; } public boolean isOverdue() { return LocalDate.now().isAfter(dueDate) && returnDate == null; } public long getDaysOverdue() { if (!isOverdue()) return 0; return LocalDate.now().toEpochDay() - dueDate.toEpochDay(); } public void calculateFine(double dailyFineRate) { if (isOverdue()) { long overdueDays = getDaysOverdue(); this.fineAmount = overdueDays * dailyFineRate; } } @Override public String toString() { return String.format("BorrowRecord{member=%s, book=%s, due=%s, returned=%s}", member.getFullName(), bookCopy.getBook().getTitle(), dueDate, returnDate != null ? returnDate.toString() : "Not returned"); } }

2. Repository Layer

// Generic Repository Interface import java.util.List; import java.util.Optional; public interface Repository<T extends BaseEntity<ID>, ID> { Optional<T> findById(ID id); List<T> findAll(); T save(T entity); void delete(T entity); void deleteById(ID id); boolean existsById(ID id); long count(); } // Book Repository import java.util.*; public class BookRepository implements Repository<Book, String> { private final Map<String, Book> books = new HashMap<>(); private final Map<String, List<BookCopy>> copiesByIsbn = new HashMap<>(); @Override public Optional<Book> findById(String isbn) { return Optional.ofNullable(books.get(isbn)); } @Override public List<Book> findAll() { return new ArrayList<>(books.values()); } @Override public Book save(Book book) { books.put(book.getIsbn(), book); copiesByIsbn.put(book.getIsbn(), book.getCopies()); return book; } @Override public void delete(Book book) { books.remove(book.getIsbn()); copiesByIsbn.remove(book.getIsbn()); } @Override public void deleteById(String isbn) { books.remove(isbn); copiesByIsbn.remove(isbn); } @Override public boolean existsById(String isbn) { return books.containsKey(isbn); } @Override public long count() { return books.size(); } // Custom queries public List<Book> findByTitle(String title) { return books.values().stream() .filter(book -> book.getTitle().toLowerCase().contains(title.toLowerCase())) .toList(); } public List<Book> findByAuthor(String author) { return books.values().stream() .filter(book -> book.getAuthor().toLowerCase().contains(author.toLowerCase())) .toList(); } public List<Book> findByGenre(String genre) { return books.values().stream() .filter(book -> book.getGenre().equalsIgnoreCase(genre)) .toList(); } public List<Book> findAvailableBooks() { return books.values().stream() .filter(Book::isAvailable) .toList(); } public Optional<BookCopy> findAvailableCopy(String isbn) { return copiesByIsbn.getOrDefault(isbn, Collections.emptyList()).stream() .filter(BookCopy::isAvailable) .findFirst(); } } // Member Repository import java.util.*; public class MemberRepository implements Repository<Member, Long> { private final Map<Long, Member> members = new HashMap<>(); private final Map<String, Member> membersById = new HashMap<>(); private long nextId = 1; @Override public Optional<Member> findById(Long id) { return Optional.ofNullable(members.get(id)); } public Optional<Member> findByMemberId(String memberId) { return Optional.ofNullable(membersById.get(memberId)); } @Override public List<Member> findAll() { return new ArrayList<>(members.values()); } @Override public Member save(Member member) { if (member.getId() == null) { member.setId(nextId++); } members.put(member.getId(), member); membersById.put(member.getMemberId(), member); return member; } @Override public void delete(Member member) { members.remove(member.getId()); membersById.remove(member.getMemberId()); } @Override public void deleteById(Long id) { Member member = members.get(id); if (member != null) { membersById.remove(member.getMemberId()); members.remove(id); } } @Override public boolean existsById(Long id) { return members.containsKey(id); } public boolean existsByMemberId(String memberId) { return membersById.containsKey(memberId); } @Override public long count() { return members.size(); } // Custom queries public List<Member> findByName(String name) { return members.values().stream() .filter(member -> member.getFullName().toLowerCase().contains(name.toLowerCase())) .toList(); } public List<Member> findMembersWithFines() { return members.values().stream() .filter(member -> member.getOutstandingFines() > 0) .toList(); } public List<Member> findByMembershipType(Member.MembershipType type) { return members.values().stream() .filter(member -> member.getMembershipType() == type) .toList(); } } // Borrow Record Repository import java.time.LocalDate; import java.util.*; public class BorrowRecordRepository implements Repository<BorrowRecord, Long> { private final Map<Long, BorrowRecord> records = new HashMap<>(); private long nextId = 1; @Override public Optional<BorrowRecord> findById(Long id) { return Optional.ofNullable(records.get(id)); } @Override public List<BorrowRecord> findAll() { return new ArrayList<>(records.values()); } @Override public BorrowRecord save(BorrowRecord record) { if (record.getId() == null) { record.setId(nextId++); } records.put(record.getId(), record); return record; } @Override public void delete(BorrowRecord record) { records.remove(record.getId()); } @Override public void deleteById(Long id) { records.remove(id); } @Override public boolean existsById(Long id) { return records.containsKey(id); } @Override public long count() { return records.size(); } // Custom queries public List<BorrowRecord> findByMember(Long memberId) { return records.values().stream() .filter(record -> record.getMember().getId().equals(memberId)) .toList(); } public List<BorrowRecord> findByBookCopy(Long bookCopyId) { return records.values().stream() .filter(record -> record.getBookCopy().getId().equals(bookCopyId)) .toList(); } public List<BorrowRecord> findOverdueRecords() { return records.values().stream() .filter(BorrowRecord::isOverdue) .toList(); } public List<BorrowRecord> findActiveRecords() { return records.values().stream() .filter(record -> record.getReturnDate() == null) .toList(); } public Optional<BorrowRecord> findActiveRecordByBookCopy(Long bookCopyId) { return records.values().stream() .filter(record -> record.getBookCopy().getId().equals(bookCopyId)) .filter(record -> record.getReturnDate() == null) .findFirst(); } }

3. Service Layer

// Library Service Interface import java.util.List; import java.util.Optional; public interface LibraryService { // Book operations Book addBook(Book book); Optional<Book> findBookByIsbn(String isbn); List<Book> searchBooksByTitle(String title); List<Book> searchBooksByAuthor(String author); List<Book> getAvailableBooks(); // Member operations Member registerMember(Member member); Optional<Member> findMemberById(String memberId); List<Member> searchMembersByName(String name); // Borrow operations BorrowResult borrowBook(String memberId, String isbn); ReturnResult returnBook(String memberId, String isbn, int copyNumber); List<BorrowRecord> getMemberBorrowHistory(String memberId); List<BorrowRecord> getOverdueRecords(); // Fine operations double calculateMemberFines(String memberId); PaymentResult payFine(String memberId, double amount); // Reports LibraryReport generateReport(); } // Main Library Service Implementation import java.time.LocalDate; import java.util.*; public class LibraryServiceImpl implements LibraryService { private final BookRepository bookRepository; private final MemberRepository memberRepository; private final BorrowRecordRepository borrowRecordRepository; private final double dailyFineRate = 0.50; // $0.50 per day private final int maxRenewals = 2; public LibraryServiceImpl(BookRepository bookRepository, MemberRepository memberRepository, BorrowRecordRepository borrowRecordRepository) { this.bookRepository = bookRepository; this.memberRepository = memberRepository; this.borrowRecordRepository = borrowRecordRepository; } // Book operations @Override public Book addBook(Book book) { if (bookRepository.existsById(book.getIsbn())) { throw new LibraryException("Book with ISBN " + book.getIsbn() + " already exists"); } return bookRepository.save(book); } @Override public Optional<Book> findBookByIsbn(String isbn) { return bookRepository.findById(isbn); } @Override public List<Book> searchBooksByTitle(String title) { return bookRepository.findByTitle(title); } @Override public List<Book> searchBooksByAuthor(String author) { return bookRepository.findByAuthor(author); } @Override public List<Book> getAvailableBooks() { return bookRepository.findAvailableBooks(); } // Member operations @Override public Member registerMember(Member member) { if (memberRepository.existsByMemberId(member.getMemberId())) { throw new LibraryException("Member with ID " + member.getMemberId() + " already exists"); } return memberRepository.save(member); } @Override public Optional<Member> findMemberById(String memberId) { return memberRepository.findByMemberId(memberId); } @Override public List<Member> searchMembersByName(String name) { return memberRepository.findByName(name); } // Borrow operations @Override public BorrowResult borrowBook(String memberId, String isbn) { Member member = memberRepository.findByMemberId(memberId) .orElseThrow(() -> new LibraryException("Member not found: " + memberId)); Book book = bookRepository.findById(isbn) .orElseThrow(() -> new LibraryException("Book not found: " + isbn)); // Validation checks if (!member.canBorrowMoreBooks()) { return BorrowResult.failure("Member cannot borrow more books. Current: " + member.getCurrentlyBorrowedCount() + "/" + member.getMaxBooksAllowed() + ", Fines: $" + member.getOutstandingFines()); } if (!book.isAvailable()) { return BorrowResult.failure("No available copies of: " + book.getTitle()); } BookCopy availableCopy = bookRepository.findAvailableCopy(isbn) .orElseThrow(() -> new LibraryException("No available copy found")); // Create borrow record BorrowRecord record = new BorrowRecord(member, availableCopy); availableCopy.setAvailable(false); book.updateAvailableCopies(); borrowRecordRepository.save(record); member.getBorrowHistory().add(record); return BorrowResult.success(record, "Book borrowed successfully. Due date: " + record.getDueDate()); } @Override public ReturnResult returnBook(String memberId, String isbn, int copyNumber) { Member member = memberRepository.findByMemberId(memberId) .orElseThrow(() -> new LibraryException("Member not found: " + memberId)); Book book = bookRepository.findById(isbn) .orElseThrow(() -> new LibraryException("Book not found: " + isbn)); // Find the active borrow record BorrowRecord activeRecord = borrowRecordRepository.findActiveRecords().stream() .filter(record -> record.getMember().getMemberId().equals(memberId)) .filter(record -> record.getBookCopy().getBook().getIsbn().equals(isbn)) .filter(record -> record.getBookCopy().getCopyNumber() == copyNumber) .findFirst() .orElseThrow(() -> new LibraryException("No active borrow record found")); // Update record activeRecord.setReturnDate(LocalDate.now()); activeRecord.setStatus("RETURNED"); // Calculate fine if overdue if (activeRecord.isOverdue()) { activeRecord.calculateFine(dailyFineRate); member.addFine(activeRecord.getFineAmount()); } // Make book copy available again activeRecord.getBookCopy().setAvailable(true); book.updateAvailableCopies(); return ReturnResult.success(activeRecord, "Book returned successfully." + (activeRecord.getFineAmount() > 0 ? " Overdue fine: $" + activeRecord.getFineAmount() : "")); } @Override public List<BorrowRecord> getMemberBorrowHistory(String memberId) { Member member = memberRepository.findByMemberId(memberId) .orElseThrow(() -> new LibraryException("Member not found: " + memberId)); return borrowRecordRepository.findByMember(member.getId()); } @Override public List<BorrowRecord> getOverdueRecords() { return borrowRecordRepository.findOverdueRecords(); } // Fine operations @Override public double calculateMemberFines(String memberId) { Member member = memberRepository.findByMemberId(memberId) .orElseThrow(() -> new LibraryException("Member not found: " + memberId)); // Calculate fines for active overdue records double totalFines = member.getOutstandingFines(); List<BorrowRecord> activeRecords = borrowRecordRepository.findByMember(member.getId()) .stream() .filter(record -> record.getReturnDate() == null) .filter(BorrowRecord::isOverdue) .toList(); for (BorrowRecord record : activeRecords) { record.calculateFine(dailyFineRate); totalFines += record.getFineAmount(); } return totalFines; } @Override public PaymentResult payFine(String memberId, double amount) { Member member = memberRepository.findByMemberId(memberId) .orElseThrow(() -> new LibraryException("Member not found: " + memberId)); if (amount <= 0) { return PaymentResult.failure("Payment amount must be positive"); } double currentFines = member.getOutstandingFines(); if (amount > currentFines) { return PaymentResult.failure("Payment amount exceeds outstanding fines"); } member.payFine(amount); return PaymentResult.success(amount, "Payment of $" + amount + " successful. Remaining fines: $" + member.getOutstandingFines()); } // Reports @Override public LibraryReport generateReport() { return new LibraryReport( bookRepository.count(), memberRepository.count(), borrowRecordRepository.findActiveRecords().size(), borrowRecordRepository.findOverdueRecords().size(), memberRepository.findMembersWithFines().stream() .mapToDouble(Member::getOutstandingFines) .sum() ); } } // Result classes public class BorrowResult { private final boolean success; private final String message; private final BorrowRecord record; private BorrowResult(boolean success, String message, BorrowRecord record) { this.success = success; this.message = message; this.record = record; } public static BorrowResult success(BorrowRecord record, String message) { return new BorrowResult(true, message, record); } public static BorrowResult failure(String message) { return new BorrowResult(false, message, null); } // Getters public boolean isSuccess() { return success; } public String getMessage() { return message; } public BorrowRecord getRecord() { return record; } } public class ReturnResult { private final boolean success; private final String message; private final BorrowRecord record; private final double fineAmount; private ReturnResult(boolean success, String message, BorrowRecord record, double fineAmount) { this.success = success; this.message = message; this.record = record; this.fineAmount = fineAmount; } public static ReturnResult success(BorrowRecord record, String message) { return new ReturnResult(true, message, record, record.getFineAmount()); } public static ReturnResult failure(String message) { return new ReturnResult(false, message, null, 0); } // Getters public boolean isSuccess() { return success; } public String getMessage() { return message; } public BorrowRecord getRecord() { return record; } public double getFineAmount() { return fineAmount; } } public class PaymentResult { private final boolean success; private final String message; private final double amountPaid; private final double remainingFines; private PaymentResult(boolean success, String message, double amountPaid, double remainingFines) { this.success = success; this.message = message; this.amountPaid = amountPaid; this.remainingFines = remainingFines; } public static PaymentResult success(double amountPaid, String message) { return new PaymentResult(true, message, amountPaid, 0); // remaining calculated separately } public static PaymentResult failure(String message) { return new PaymentResult(false, message, 0, 0); } // Getters public boolean isSuccess() { return success; } public String getMessage() { return message; } public double getAmountPaid() { return amountPaid; } public double getRemainingFines() { return remainingFines; } } // Report class public class LibraryReport { private final long totalBooks; private final long totalMembers; private final long currentlyBorrowed; private final long overdueBooks; private final double totalFines; private final LocalDate generatedDate; public LibraryReport(long totalBooks, long totalMembers, long currentlyBorrowed, long overdueBooks, double totalFines) { this.totalBooks = totalBooks; this.totalMembers = totalMembers; this.currentlyBorrowed = currentlyBorrowed; this.overdueBooks = overdueBooks; this.totalFines = totalFines; this.generatedDate = LocalDate.now(); } // Getters public long getTotalBooks() { return totalBooks; } public long getTotalMembers() { return totalMembers; } public long getCurrentlyBorrowed() { return currentlyBorrowed; } public long getOverdueBooks() { return overdueBooks; } public double getTotalFines() { return totalFines; } public LocalDate getGeneratedDate() { return generatedDate; } @Override public String toString() { return String.format( "Library Report (%s)\n" + "Total Books: %d\n" + "Total Members: %d\n" + "Currently Borrowed: %d\n" + "Overdue Books: %d\n" + "Total Outstanding Fines: $%.2f", generatedDate, totalBooks, totalMembers, currentlyBorrowed, overdueBooks, totalFines ); } } // Custom Exception public class LibraryException extends RuntimeException { public LibraryException(String message) { super(message); } public LibraryException(String message, Throwable cause) { super(message, cause); } }

4. Console User Interface

import java.util.*; import java.time.Year; public class LibraryConsoleUI { private final LibraryService libraryService; private final Scanner scanner; public LibraryConsoleUI(LibraryService libraryService) { this.libraryService = libraryService; this.scanner = new Scanner(System.in); } public void start() { System.out.println("=== Library Management System ==="); while (true) { displayMainMenu(); int choice = getIntInput("Enter your choice: "); switch (choice) { case 1 -> manageBooks(); case 2 -> manageMembers(); case 3 -> manageBorrowing(); case 4 -> manageReturns(); case 5 -> generateReports(); case 6 -> manageFines(); case 0 -> { System.out.println("Thank you for using Library Management System!"); return; } default -> System.out.println("Invalid choice. Please try again."); } } } private void displayMainMenu() { System.out.println("\n--- Main Menu ---"); System.out.println("1. Manage Books"); System.out.println("2. Manage Members"); System.out.println("3. Borrow Books"); System.out.println("4. Return Books"); System.out.println("5. Reports"); System.out.println("6. Manage Fines"); System.out.println("0. Exit"); } private void manageBooks() { while (true) { System.out.println("\n--- Book Management ---"); System.out.println("1. Add New Book"); System.out.println("2. Search Books by Title"); System.out.println("3. Search Books by Author"); System.out.println("4. View Available Books"); System.out.println("5. View All Books"); System.out.println("0. Back to Main Menu"); int choice = getIntInput("Enter your choice: "); switch (choice) { case 1 -> addNewBook(); case 2 -> searchBooksByTitle(); case 3 -> searchBooksByAuthor(); case 4 -> viewAvailableBooks(); case 5 -> viewAllBooks(); case 0 -> { return; } default -> System.out.println("Invalid choice."); } } } private void addNewBook() { System.out.println("\n--- Add New Book ---"); String isbn = getStringInput("ISBN: "); String title = getStringInput("Title: "); String author = getStringInput("Author: "); String publisher = getStringInput("Publisher: "); int publicationYear = getIntInput("Publication Year: "); String genre = getStringInput("Genre: "); int totalCopies = getIntInput("Total Copies: "); try { Book book = new Book(isbn, title, author, publisher, Year.of(publicationYear), genre, totalCopies); libraryService.addBook(book); System.out.println("Book added successfully!"); } catch (LibraryException e) { System.out.println("Error: " + e.getMessage()); } } private void searchBooksByTitle() { String title = getStringInput("Enter title to search: "); List<Book> books = libraryService.searchBooksByTitle(title); displayBooks(books); } private void searchBooksByAuthor() { String author = getStringInput("Enter author to search: "); List<Book> books = libraryService.searchBooksByAuthor(author); displayBooks(books); } private void viewAvailableBooks() { List<Book> books = libraryService.getAvailableBooks(); displayBooks(books); } private void viewAllBooks() { // This would require adding a method to get all books System.out.println("Feature not implemented in this version."); } private void displayBooks(List<Book> books) { if (books.isEmpty()) { System.out.println("No books found."); return; } System.out.println("\n--- Books Found ---"); for (int i = 0; i < books.size(); i++) { Book book = books.get(i); System.out.printf("%d. %s\n", i + 1, book); } } private void manageMembers() { while (true) { System.out.println("\n--- Member Management ---"); System.out.println("1. Register New Member"); System.out.println("2. Search Members by Name"); System.out.println("3. View Member Details"); System.out.println("0. Back to Main Menu"); int choice = getIntInput("Enter your choice: "); switch (choice) { case 1 -> registerNewMember(); case 2 -> searchMembersByName(); case 3 -> viewMemberDetails(); case 0 -> { return; } default -> System.out.println("Invalid choice."); } } } private void registerNewMember() { System.out.println("\n--- Register New Member ---"); String memberId = getStringInput("Member ID: "); String firstName = getStringInput("First Name: "); String lastName = getStringInput("Last Name: "); String email = getStringInput("Email: "); String phone = getStringInput("Phone: "); System.out.println("Membership Types:"); for (Member.MembershipType type : Member.MembershipType.values()) { System.out.printf("- %s (Max books: %d, Loan period: %d days)\n", type, type.getMaxBooks(), type.getLoanPeriodDays()); } String typeInput = getStringInput("Membership Type: ").toUpperCase(); try { Member.MembershipType membershipType = Member.MembershipType.valueOf(typeInput); Member member = new Member(memberId, firstName, lastName, email, phone, membershipType); libraryService.registerMember(member); System.out.println("Member registered successfully!"); } catch (IllegalArgumentException e) { System.out.println("Invalid membership type."); } catch (LibraryException e) { System.out.println("Error: " + e.getMessage()); } } private void searchMembersByName() { String name = getStringInput("Enter name to search: "); List<Member> members = libraryService.searchMembersByName(name); displayMembers(members); } private void viewMemberDetails() { String memberId = getStringInput("Enter Member ID: "); Optional<Member> memberOpt = libraryService.findMemberById(memberId); if (memberOpt.isPresent()) { Member member = memberOpt.get(); System.out.println("\n--- Member Details ---"); System.out.println("ID: " + member.getMemberId()); System.out.println("Name: " + member.getFullName()); System.out.println("Email: " + member.getEmail()); System.out.println("Phone: " + member.getPhone()); System.out.println("Membership Type: " + member.getMembershipType()); System.out.println("Currently Borrowed: " + member.getCurrentlyBorrowedCount() + "/" + member.getMaxBooksAllowed()); System.out.println("Outstanding Fines: $" + member.getOutstandingFines()); // Show borrow history List<BorrowRecord> history = libraryService.getMemberBorrowHistory(memberId); if (!history.isEmpty()) { System.out.println("\nBorrow History:"); for (BorrowRecord record : history) { System.out.println(" - " + record.getBookCopy().getBook().getTitle() + " (Due: " + record.getDueDate() + ", Returned: " + (record.getReturnDate() != null ? record.getReturnDate() : "Not yet") + ")"); } } } else { System.out.println("Member not found."); } } private void displayMembers(List<Member> members) { if (members.isEmpty()) { System.out.println("No members found."); return; } System.out.println("\n--- Members Found ---"); for (int i = 0; i < members.size(); i++) { Member member = members.get(i); System.out.printf("%d. %s\n", i + 1, member); } } private void manageBorrowing() { System.out.println("\n--- Borrow Book ---"); String memberId = getStringInput("Member ID: "); String isbn = getStringInput("Book ISBN: "); BorrowResult result = libraryService.borrowBook(memberId, isbn); if (result.isSuccess()) { System.out.println("Success: " + result.getMessage()); } else { System.out.println("Error: " + result.getMessage()); } } private void manageReturns() { System.out.println("\n--- Return Book ---"); String memberId = getStringInput("Member ID: "); String isbn = getStringInput("Book ISBN: "); int copyNumber = getIntInput("Copy Number: "); ReturnResult result = libraryService.returnBook(memberId, isbn, copyNumber); if (result.isSuccess()) { System.out.println("Success: " + result.getMessage()); } else { System.out.println("Error: " + result.getMessage()); } } private void manageFines() { while (true) { System.out.println("\n--- Fine Management ---"); System.out.println("1. Calculate Member Fines"); System.out.println("2. Pay Fines"); System.out.println("0. Back to Main Menu"); int choice = getIntInput("Enter your choice: "); switch (choice) { case 1 -> calculateFines(); case 2 -> payFines(); case 0 -> { return; } default -> System.out.println("Invalid choice."); } } } private void calculateFines() { String memberId = getStringInput("Enter Member ID: "); double fines = libraryService.calculateMemberFines(memberId); System.out.printf("Total fines for member %s: $%.2f\n", memberId, fines); } private void payFines() { String memberId = getStringInput("Enter Member ID: "); double amount = getDoubleInput("Enter payment amount: "); PaymentResult result = libraryService.payFine(memberId, amount); if (result.isSuccess()) { System.out.println("Success: " + result.getMessage()); } else { System.out.println("Error: " + result.getMessage()); } } private void generateReports() { System.out.println("\n--- Library Reports ---"); LibraryReport report = libraryService.generateReport(); System.out.println(report); // Show overdue records List<BorrowRecord> overdueRecords = libraryService.getOverdueRecords(); if (!overdueRecords.isEmpty()) { System.out.println("\n--- Overdue Books ---"); for (BorrowRecord record : overdueRecords) { System.out.printf("- %s borrowed by %s (Due: %s, Overdue: %d days)\n", record.getBookCopy().getBook().getTitle(), record.getMember().getFullName(), record.getDueDate(), record.getDaysOverdue()); } } } // Utility methods for input private String getStringInput(String prompt) { System.out.print(prompt); return scanner.nextLine().trim(); } private int getIntInput(String prompt) { while (true) { try { System.out.print(prompt); return Integer.parseInt(scanner.nextLine().trim()); } catch (NumberFormatException e) { System.out.println("Please enter a valid number."); } } } private double getDoubleInput(String prompt) { while (true) { try { System.out.print(prompt); return Double.parseDouble(scanner.nextLine().trim()); } catch (NumberFormatException e) { System.out.println("Please enter a valid amount."); } } } }

5. Main Application Class

public class LibraryManagementSystem { public static void main(String[] args) { // Initialize repositories BookRepository bookRepository = new BookRepository(); MemberRepository memberRepository = new MemberRepository(); BorrowRecordRepository borrowRecordRepository = new BorrowRecordRepository(); // Initialize service LibraryService libraryService = new LibraryServiceImpl( bookRepository, memberRepository, borrowRecordRepository); // Initialize UI LibraryConsoleUI ui = new LibraryConsoleUI(libraryService); // Add some sample data initializeSampleData(libraryService); // Start the application ui.start(); } private static void initializeSampleData(LibraryService libraryService) { try { // Add sample books libraryService.addBook(new Book("978-0134685991", "Effective Java", "Joshua Bloch", "Addison-Wesley", Year.of(2018), "Programming", 3)); libraryService.addBook(new Book("978-1617293290", "Spring in Action", "Craig Walls", "Manning", Year.of(2020), "Programming", 2)); libraryService.addBook(new Book("978-0596009205", "Head First Design Patterns", "Eric Freeman", "O'Reilly", Year.of(2020), "Programming", 4)); // Register sample members libraryService.registerMember(new Member("MEM001", "John", "Doe", "[email protected]", "555-0101", Member.MembershipType.FACULTY)); libraryService.registerMember(new Member("MEM002", "Jane", "Smith", "[email protected]", "555-0102", Member.MembershipType.STUDENT)); System.out.println("Sample data initialized successfully!"); } catch (LibraryException e) { System.out.println("Error initializing sample data: " + e.getMessage()); } } }

Features Included

Book Management

Add new books with multiple copies
Search books by title, author, genre
Track available copies

Member Management

Member registration with different membership types
Search members by name
View member details and borrowing history

Borrowing System

Borrow books with validation checks
Automatic due date calculation based on membership type
Prevent over-borrowing and track fines

Return System

Process book returns
Calculate overdue fines automatically
Update book availability

Fine Management

Calculate outstanding fines
Process fine payments
Prevent borrowing when fines exist

Reporting

Library statistics
Overdue books tracking
Financial reports

Key Design Patterns Used

Repository Pattern for data access
Service Layer Pattern for business logic
DTO Pattern for data transfer
Factory Pattern for object creation
Strategy Pattern for different membership types

This Library Management System provides a solid foundation that can be extended with database persistence, web interfaces, or additional features like reservations, renewals, and email notifications.