Here, we’ll create the class diagram for our system on the basis of the requirements that we gathered previously. In the class diagram, we will first design/create the classes, abstract classes, and interfaces for the system, and then we’ll identify the relationship between classes in accordance with all requirements of the library management system.

Components of a library management system

In this section, we will define the classes for LMS. Since we are following the bottom-up approach for designing a class diagram, we’ll first create the classes of small components. After that, we will integrate those components and create the class diagram for the whole library management system.

Book and book item

The Book class represents the conceptual essence of a book. This includes the metadata or descriptive information about a book, which isn’t specific to any single physical copy. It’s a blueprint that captures the shared attributes of all instances or copies of the book as they exist in the world or within the library’s collection.

The BookItem class, on the other hand, represents a specific physical or digital instance of a Book in the library’s collection. This class extends the concept represented by the Book class to the practical level of inventory and circulation management. It deals with the properties and behaviors associated with individual copies of a book that patrons can borrow, reserve, or reference within the library. Each BookItem has its unique attributes that manage and track its status within the library system. The UML representation of Book and BookItem is shown in the class diagram below:

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