Class Diagram for the Hotel Management System

Here, we are going to create the class diagram for our system on the basis of requirements that we gathered in one of the previous lessons. In the class diagram, we will first design and create the classes, abstract classes, and interfaces for the system, and then we’ll identify the relationship between classes in accordance with all the requirements of the hotel management system.

Components of a hotel management system#

In this section, we’ll define the classes for a hotel management system. Since we are following the bottom-up approach to designing a class diagram, we will create the classes of small components first. Next, we will integrate these components and create the class diagram for the entire hotel management system.

Address and Account#

The Address is a class that is required to store any address. The Address is a custom data type that has attributes like a street address, city, etc. In the hotel management system, this class will be used to specify the address of the users and the hotel.

Account is a class that is used to store the account information of the user. This class has three members, i.e., account ID, password, and the status of the account. The class representation of Address and Account classes is as follows:

Person #

Person is an abstract class used to store information related to a person like a name, email, phone number, etc. In this class, there is an object of the Address type to specify the person’s address. The Person class specifies the accounts in the system. There can be four types of accounts in the system,i.e., housekeeper, receptionist, guest, and server.

There are multiple functions of the Person class’s subclasses. First, the Housekeeper class will keep track of the housekeeping records of a room. Second, the Receptionist class represents the hotel receptionist. The methods in this class depict the actions that can be performed by the receptionist. Moreover, the Guest class describes the guests of the hotel. Guests are the customers of the hotel who can search for and book a room. Whereas, the Server class will handle the room service.

The relationship diagram for these classes is shown below:

Service#

Service is an abstract class that encapsulates the details of different types of services that guests have requested. There are three types of services provided—amenity, room service, and kitchen service.

The Amenity class is a subclass of Service having two members; name and description. Similarly, RoomService is also inherited from the Service class. This class stores information about room services whether these services are chargeable or not and what is the request time of the service. Furthermore, the last child class of the Service is the KitchenService. The relationship between these classes is shown in the illustration below.

Invoice#

The Invoice class represents the billing system in the hotel management system. The UML diagram for both classes is presented below:

Room booking#

The RoomBooking class is responsible for managing the bookings for a room. This class consists of attributes like reservation number, start date, duration, etc. Moreover, this class has a member of the BookingStatus type that is used to store the status of the room booking. The UML representation of this class is as follows:

Notification#

Notification is an abstract class. This class is responsible for sending notifications to guests whenever the booking is nearing the check-in or check-out date. Every notification has an ID, creation date, and content in it. The notification can either be an SMS notification or an email notification.

The SMSNotification class requires the phone number of the member to send a notification. On the other hand, the EmailNotification needs the email address of the member to send a notification. The relationship diagram of these classes is shown here:

Room, room key, and room housekeeping#

The Room class is the basic building block of the system. Every room has a room number and price associated with it. The Room class uses the RoomStyle and RoomStatus enums to specify the style and status of the rooms, respectively.

Each room has an electronic key card associated with it. The RoomKey class expresses the electronic key card. Each card has its own unique ID and barcode on it. The RoomKey class also has members to store the issue date, to check whether or not the key is active, and to check whether or not a key is a master key. Whereas, RoomHousekeeping is a class used to keep track of all housekeeping records for the rooms. The UML representation of these classes is as follows:

Search interface and catalog #

Search is one of the most important components of the hotel management system. In the diagram below, Search is the interface that allows the guest to search for any room of their choice and pay range. The receptionist can also use this interface to search for any room. The Catalog class contains a list of all rooms and implements the Search interface.

The following UML diagram shows this relationship:

Bill transaction#

After generating an invoice, a customer needs to pay the bill to confirm the booking of the room. A BillTransaction class is required to store the information of bill payment. Three ways to pay the bill are check transaction, cash transaction, and credit card transaction. We can define the bill payment functionality through any payment method using the diagram below:

Hotel and hotel branch#

In this section, we’ll look at the Hotel and HotelBranch classes. According to the requirements, there can be multiple branches of the hotel. HotelBranch is a class used to represent the location of the hotel branch. This class consists of two members: name and Address. The string type name is used to store the name of the hotel branch, while the complex object Address is used to store the complete address of a branch.

The Hotel class is the base class of the system which is used to represent the hotel. The visual representation of these classes is as follows:

Enumerations #

Here is the list of enumerations required in the hotel management system:

BookingStatus: This status describes the status of the booking whether the booking is requested, pending, confirmed, canceled, or abandoned.

PaymentStatus: This status describes the status of the booking’s payment, whether it is unpaid, pending, completed, failed, declined, canceled, abandoned, setting, settled, or refunded.

RoomStatus: This status describes the status of the room, whether it is available, reserved, occupied, not available, being serviced, or any other possibility.

RoomStyle: This describes the style of the room that the user wants to book. The style could be standard, deluxe, family suite, or business suite.

AccountStatus: This status tells the status of the user account whether it is active, closed, canceled, or blocklisted.

AccountType: The account type tells the type of the account of the user, whether it is a member, guest, manager, or receptionist.

Relationship between the classes#

Now, we’ll discuss the relationships between the classes we have defined above in our hotel management system.

Association#

The class diagram has the following association relationships:

One-way association#

• The Housekeeper class has a one-way association with RoomHousekeeping.

• Both Receptionist and Guest have a one-way association with RoomBooking.

• The RoomBooking class has a one-way association with Room.

Two-way association#

The RoomBooking class has a two-way association with Notification.

Aggregation#

• The RoomBooking class is an aggregate of Service.

Composition#

• The RoomBooking class is composed of Invoice.

• The Invoice class is composed of BillTransaction.

• The Person class is composed of Account.

• The Room class is composed of RoomHousekeeping and RoomKey.

• The HotelBranch class is composed of Room.

• The Hotel class is composed of HotelBranch.

Inheritance#

The following classes show an inheritance relationship:

• Receptionist, Guest, Housekeeper, and Server classes extend the Person class.

• Amenity, RoomService, and KitchenService classes extend the Service class.

• Both PostalNotification and EmailNotification classes extend the Notification class.

• The Catalog class implements the Search interface.

Note: We have already discussed the inheritance relationship between classes in the component section above one by one.

Class diagram of the hotel management system#

Here is the complete class diagram for our hotel management system:

Design pattern#

The Strategy design pattern is applied here, which will design a separate strategy or algorithm to calculate the rate of each room.

The Hotel class follows the Singleton design pattern, because there will only be a single instance of the Hotel class.

Inside the hotel management system, there can be multiple rooms in a hotel, and each room has its own formula for calculating the booking cost. Therefore, Room and related classes incorporate the properties of the Factory design pattern.

AI-powered trainer#

At this stage, everything should be clear. If you encounter any confusion or ambiguity, feel free to utilize the interactive AI-enabled widget below to seek clarification. This tool is designed to assist you in strengthening your understanding of the concepts.

Additional requirements#

The interviewer can introduce some additional requirements in the given hotel management system, or they can ask some follow-up questions. Let's see examples of the additional requirements:

Discount: A discount will be applied to the payment depending on special events such as the new year, branch opening, and so on. The class diagram provided below shows the relationship of Discount with the BillTransaction class:

We have successfully designed the class diagram for the hotel management system. Let’s move to the next lesson to see how we can construct the sequence diagram for the system.