This chapter aims to reinforce the understanding of Object-Oriented Programming (OOP) through a case study, a practical real-world example.

# Case Study: Simple Library System

Let's consider a simple library system. This system needs to manage books, members, and loans.

Let's see how OOP concepts are applied here.

Book Class:

// Class representing a book in the library
public class Book {
    private String title;
    private String author;
    private String isbn;

    // Book class constructor
    public Book(String title, String author, String isbn) {
        this.title = title;
        this.author = author;
        this.isbn = isbn;
    }

    // Getters
    public String getTitle() {
        return title;
    }

    public String getAuthor() {
        return author;
    }

    public String getIsbn() {
        return isbn;
    }

    // Setters
    public void setTitle(String title) {
        this.title = title;
    }

    public void setAuthor(String author) {
        this.author = author;
    }

    public void setIsbn(String isbn) {
        this.isbn = isbn;
    }
}

Member Class:

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

// Class representing a library member
public class Member {
    private String name;
    private String id;
    private List<Book> borrowedBooks;

    // Member class constructor
    public Member(String name, String id) {
        this.name = name;
        this.id = id;
        this.borrowedBooks = new ArrayList<>();
    }

    // Method to lend a book to the member
    public void borrowBook(Book book) {
        borrowedBooks.add(book);
    }

    // Getters
    public String getName() {
        return name;
    }

    public String getId() {
        return id;
    }

    public List<Book> getBorrowedBooks() {
        return borrowedBooks;
    }

    // Setters
    public void setName(String name) {
        this.name = name;
    }

    public void setId(String id) {
        this.id = id;
    }
}

Library Class:

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

// Class representing the library
public class Library {
    private List<Book> availableBooks;
    private List<Member> members;

    // Library class constructor
    public Library() {
        this.availableBooks = new ArrayList<>();
        this.members = new ArrayList<>();
    }

    // Method to add a book to the library
    public void addBook(Book book) {
        availableBooks.add(book);
    }

    // Method to register a new member in the library
    public void registerMember(Member member) {
        members.add(member);
    }

    // Additional methods to manage loans, returns, etc.

    // Getters
    public List<Book> getAvailableBooks() {
        return availableBooks;
    }

    public List<Member> getMembers() {
        return members;
    }
}

In this simple example, we can see how OOP facilitates the management and organization of the system:

• Encapsulation: Each class (Book, Member, Library) encapsulates its own data and behaviors.

• Abstraction: Complex operations, such as lending or returning books, are abstracted behind methods.

• Reuse: Classes can be reused and extended to create more complex systems.

# Conclusions

Applying OOP concepts to build a library system, we have seen how abstraction, encapsulation, and code reuse facilitate the creation of structured and maintainable software.