Hotel Control System

A robust, CLI-based Hotel Management System featuring a custom AVL-Tree Map implementation.

Table of Contents

• 1. About the Project
• 2. Key Features
• 3. Technical Highlights
  • Custom Map Implementation
  • Design Patterns
• 4. Project Structure
• 5. Getting Started
  • Prerequisites
  • Installation
• 6. Usage
  • Running the Application
  • Command Examples
• 7. Quality Assurance

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1. About the Project

This project was developed as a comprehensive exercise in Java programming, focusing on Object-Oriented Programming (OOP) principles, algorithm implementation, and software architecture.

The core objective was to create a functional Hotel Management System that operates via a text-based interface (REPL). A critical requirement was to implement a custom Map data structure from scratch (without relying on java.util.HashMap or TreeMap for internal storage) and use it to manage the hotel's data.

Bonuses Implemented:

• ✅ Bonus 1: Loading hotel configuration/state from an external CSV file on startup.
• ✅ Bonus 2: Persisting the current hotel state (rooms, guests, reservations) to a CSV file.

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2. Key Features

The system provides a fully interactive command-line interface to manage hotel operations:

• Check-in: Register new guests into rooms with validation (capacity, occupancy).
• Check-out: Process guest departures and calculate the total bill based on stay duration.
• View Room: Display detailed information about a specific room (price, capacity, current residents).
• List All: Show a formatted table of all rooms, their status (Free/Occupied), and main guest details.
• Prices: Display a price list for all rooms.
• Persistence: Save and Load the entire hotel state to/from CSV files.

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3. Technical Highlights

Custom Map Implementation

Instead of using standard Java collections, this project features a custom, generic implementation of a Map: MyMap<K, V>.

• Data Structure: AVL Tree (Self-balancing Binary Search Tree).
• Complexity: Guaranteed O(log n) for put, get, and remove operations.
• Features: Automatic balancing (rotations), generic key/value support, custom iterator.
• Location: my-map-implementation module.

Design Patterns

The architecture adheres to SOLID principles and utilizes standard design patterns:

1. Command Pattern: Encapsulates user actions (CheckinCommand, ListCommand, etc.) implementing a common interface.
2. Factory Pattern: The CommandRegistry dynamically creates command instances based on user input using Java Reflection.
3. Strategy Pattern: The execution logic is decoupled from the command selection.

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4. Project Structure

The project is organized as a Multi-Module Maven project:

hotel-control-system/
├── hotel-main/                # Application logic & Entry point
│   ├── src/main/java/
│   │   ├── commandcontrol/    # Commands & Registry (Controller)
│   │   ├── model/             # Hotel, Room, Guest, Reservation (Model)
│   │   └── HotelApplication.java
│   └── src/test/java/         # Unit tests for logic
├── my-map-implementation/     # Utility library (hotel-utils)
│   ├── src/main/java/
│   │   └── map/               # MyMap (AVL Tree) implementation
│   └── src/test/java/         # Unit tests for Data Structure
├── javadoc/                   # Generated documentation
├── sonar-qube/                # Quality reports
└── pom.xml                    # Parent POM

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5. Getting Started

Prerequisites

• Java JDK 25 (or compatible newer version)
• Apache Maven 3.6+
• (Optional) Docker for running SonarQube analysis.

Installation

1. Clone the repository:

   git clone [https://github.com/your-username/hotel-control-system.git](https://github.com/your-username/hotel-control-system.git)
   cd hotel-control-system

2. Build the project: This will compile code, run tests, and generate the "Fat JAR" (including dependencies).

   mvn clean package

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6. Usage

Running the Application

You can run the application in two modes:

1. Default Mode (Hardcoded Data):

java -jar hotel-main/target/hotel-main-1.0-SNAPSHOT-jar-with-dependencies.jar

2. File Mode (Load from CSV): Provide a path to your hotel_state.csv file as an argument.

java -jar hotel-main/target/hotel-main-1.0-SNAPSHOT-jar-with-dependencies.jar hotel_state.csv

Command Examples

The User Interface is designed to be clean and informative.

Listing all rooms (list):

---[ ALL ROOMS INFORMATION ]---
+-----------------------------------------------------------------------------------+
| Room Nr  | Status     | Main guest                | Checkin date  | Checkout date |
+-----------------------------------------------------------------------------------+
| 101      | Free       | ---                       | ---           | ---           |
| 202      | Occupied   | Alice Smith               | 2025-11-17    | 2025-11-22    |
+-----------------------------------------------------------------------------------+

Checking a guest in (checkin):

> checkin

---[ CHECK-IN ]---
Enter room number: 101
Enter main guest full name: John Doe
Enter number of additional guests (0-1): 0
Enter duration of stay (nights): 3
Enter check-in date (YYYY-MM-DD) or press Enter for today: 

Check-in completed successfully for room 101.

Saving state (save):

> save
Provide the name of the file where you want to save hotel state or press Enter for hotel_state.csv filename:
my_backup.csv

---[ SUCCESSFULLY SAVED TO THE FILE 9 ROOMS ]---

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7. Quality Assurance

The project maintains high code quality standards:

• Unit Tests: ~80% code coverage using JUnit 5 and Mockito.
  • Complex logic (AVL balancing, booking rules) is thoroughly tested.
• Static Analysis: Verified with SonarQube.
  • ✅ Zero Blocker/Critical issues.
  • ✅ "A" rating for Reliability and Security.
  • ✅ Reduced Cognitive Complexity.
• Documentation: Comprehensive Javadoc available in the /javadoc directory.

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Author

Dmitry Nikitin Student at AGH University of Science and Technology