Hotel Mgmt LLD

1. Hotels and Room Inventory

1.1. Class: Hotel
Attributes:

int hotelId
String name
String location
String description
List<String> amenities
List<RoomType> roomTypes
Methods:

void addRoomType(RoomType roomType)
Adds a new room type to the hotel's room inventory.
List<RoomType> searchAvailableRooms(Date startDate, Date endDate, List<String> amenities)
Searches and returns a list of available room types based on date range and amenities.

1.2. Class: RoomType
Attributes:
int roomTypeId
int hotelId
String type (e.g., Single, Double, Suite)
double price
int totalRooms
List<String> amenities
Map<Date, Integer> availability (Key: Date, Value: Available rooms on that date)
Methods:

boolean isAvailable(Date startDate, Date endDate)
Checks if the room type is available for the given date range.
void updateAvailability(Date date, int roomsBooked)
Updates the number of available rooms for a specific date.

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2. Booking and Reservations
2.1. Class: Reservation
Attributes:

int reservationId
int userId
int hotelId
int roomTypeId
Date checkInDate
Date checkOutDate
String status (e.g., Booked, Cancelled)
String paymentStatus (e.g., Paid, Pending, Refunded)
Methods:

boolean bookRoom()
Books a room and updates the room availability.
boolean cancelReservation()
Cancels the reservation and updates the room availability and payment status.
boolean modifyReservation(Date newCheckInDate, Date newCheckOutDate)
Modifies the reservation dates, checking for availability.

2.2. Class: ReservationManager
Methods:
Reservation createReservation(int userId, int hotelId, int roomTypeId, Date checkInDate, Date checkOutDate)
Creates a new reservation.
boolean cancelReservation(int reservationId)
Cancels an existing reservation.
boolean modifyReservation(int reservationId, Date newCheckInDate, Date newCheckOutDate)
Modifies an existing reservation.

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3. Reviews and Ratings
3.1. Class: Review
Attributes:

int reviewId
int userId
int hotelId
int roomTypeId
int rating (e.g., 1-5 stars)
String comment
Date timestamp
Methods:

void submitReview()
Allows a user to submit a review.
void editReview(int reviewId)
Allows a user to edit their existing review.
void deleteReview(int reviewId)
Allows a user to delete their review.

3.2. Class: ReviewManager
Methods:
List<Review> getHotelReviews(int hotelId)
Retrieves all reviews for a specific hotel.
double getAggregateRating(int hotelId)
Calculates and returns the aggregate rating for a hotel.

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4. Payment and Discounts
4.1. Class: Payment
Attributes:

int paymentId
int reservationId
double amount
String status (e.g., Paid, Pending, Refunded)
String paymentMethod (e.g., Credit Card, PayPal)
String transactionId
Methods:

boolean processPayment()
Processes the payment for a reservation.
boolean refundPayment()
Refunds the payment if the reservation is canceled.

4.2. Class: Discount
Attributes:

int discountId
String code
String discountType (e.g., Percentage, Fixed Amount)
double discountValue
Date validFrom
Date validTo
List<Integer> applicableHotelIds
List<Integer> applicableRoomTypeIds
Methods:

boolean isValid(Date date)
Checks if the discount is valid on the given date.
double applyDiscount(double totalAmount)
Applies the discount to the total amount.
4.3. Class: PaymentGateway
Methods:
boolean makePayment(double amount, String paymentMethod)
Interfaces with external payment gateways to process payments.
boolean refundPayment(double amount, String transactionId)
Interfaces with external payment gateways to process refunds.

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5. Admin and Reporting
5.1. Class: Admin
Attributes:

int adminId
String username
String password
String role (e.g., Hotel Manager, System Admin)
Methods:

void manageHotel(Hotel hotel)
Allows admins to manage hotel details, room types, and availability.
void createReport(String reportType)
Allows admins to generate reports such as booking history, occupancy rates, and revenue.
5.2. Class: Report
Attributes:

int reportId
String reportType (e.g., Booking, Revenue, Occupancy)
Map<String, Object> data
Date generatedDate
Methods:

Map<String, Object> generateReport()
Generates a report based on the report type and data provided.
5.3. Class: AdminPanel
Methods:
void login(String username, String password)
Authenticates admin users.
void viewDashboard()
Displays the admin dashboard with key metrics.
void manageHotels()
Provides options to manage hotel details, room types, and availability.
void viewReports()
Allows viewing and exporting generated reports.

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Inter-Class Interactions
Hotel and RoomType:
Hotels contain multiple room types. RoomType methods are invoked when searching for available rooms or updating availability.
Reservation and Payment:
When a reservation is made, the Payment class processes the payment. If the reservation is canceled, the Payment class handles the refund.
Review and Hotel:
Reviews are linked to specific hotels and room types. The ReviewManager class aggregates ratings and manages review data.
Admin and Reporting:
Admin users manage hotels, generate reports, and monitor the system through the AdminPanel.
Data Flow Example
Booking a Room:

The user searches for available hotels using Hotel.searchAvailableRooms().
The system checks room availability using RoomType.isAvailable().
Upon selecting a room, ReservationManager.createReservation() is invoked to create a reservation.
Payment.processPayment() is called to process the payment for the reservation.
The room's availability is updated using RoomType.updateAvailability().
Leaving a Review:

After a stay, the user invokes Review.submitReview() to leave feedback.
ReviewManager.getHotelReviews() can be called to display all reviews for a particular hotel.
The system aggregates ratings using ReviewManager.getAggregateRating() and displays them on the hotel's page.
Generating Reports:

Admin logs in through AdminPanel.login().
Admin navigates to the report section and uses Admin.createReport() to generate a report (e.g., occupancy rates).
The report data is populated in Report.generateReport() and displayed in the admin dashboard.




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Code
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1. Hotels and Room Inventory
1.1. Class: Hotel

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

public class Hotel {
    private int hotelId;
    private String name;
    private String location;
    private String description;
    private List<String> amenities;
    private List<RoomType> roomTypes;

    public Hotel(int hotelId, String name, String location, String description, List<String> amenities) {
        this.hotelId = hotelId;
        this.name = name;
        this.location = location;
        this.description = description;
        this.amenities = amenities;
        this.roomTypes = new ArrayList<>();
    }

    public void addRoomType(RoomType roomType) {
        this.roomTypes.add(roomType);
    }

    public List<RoomType> searchAvailableRooms(Date startDate, Date endDate, List<String> requiredAmenities) {
        List<RoomType> availableRooms = new ArrayList<>();
        for (RoomType roomType : roomTypes) {
            if (roomType.isAvailable(startDate, endDate) && roomType.hasAmenities(requiredAmenities)) {
                availableRooms.add(roomType);
            }
        }
        return availableRooms;
    }

    // Getters and setters can be added here for each field
}

1.2. Class: RoomType

import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class RoomType {
    private int roomTypeId;
    private int hotelId;
    private String type; // e.g., Single, Double, Suite
    private double price;
    private int totalRooms;
    private List<String> amenities;
    private Map<Date, Integer> availability; // Key: Date, Value: Available rooms on that date

    public RoomType(int roomTypeId, int hotelId, String type, double price, int totalRooms, List<String> amenities) {
        this.roomTypeId = roomTypeId;
        this.hotelId = hotelId;
        this.type = type;
        this.price = price;
        this.totalRooms = totalRooms;
        this.amenities = amenities;
        this.availability = new HashMap<>();
    }

    public boolean isAvailable(Date startDate, Date endDate) {
        // Check if the room type is available between the given dates
        for (Date date = startDate; !date.after(endDate); date = new Date(date.getTime() + (1000 * 60 * 60 * 24))) {
            if (availability.getOrDefault(date, totalRooms) <= 0) {
                return false;
            }
        }
        return true;
    }

    public void updateAvailability(Date date, int roomsBooked) {
        int availableRooms = availability.getOrDefault(date, totalRooms);
        availability.put(date, availableRooms - roomsBooked);
    }

    public boolean hasAmenities(List<String> requiredAmenities) {
        return amenities.containsAll(requiredAmenities);
    }

    // Getters and setters can be added here for each field
}

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2. Booking and Reservations
2.1. Class: Reservation

import java.util.Date;

public class Reservation {
    private int reservationId;
    private int userId;
    private int hotelId;
    private int roomTypeId;
    private Date checkInDate;
    private Date checkOutDate;
    private String status; // e.g., Booked, Cancelled
    private String paymentStatus; // e.g., Paid, Pending, Refunded

    public Reservation(int reservationId, int userId, int hotelId, int roomTypeId, Date checkInDate, Date checkOutDate) {
        this.reservationId = reservationId;
        this.userId = userId;
        this.hotelId = hotelId;
        this.roomTypeId = roomTypeId;
        this.checkInDate = checkInDate;
        this.checkOutDate = checkOutDate;
        this.status = "Booked";
        this.paymentStatus = "Pending";
    }

    public boolean bookRoom() {
        // Logic to book a room and update availability
        // Update room availability in RoomType
        return true;
    }

    public boolean cancelReservation() {
        this.status = "Cancelled";
        // Logic to handle cancellation, update availability, and process refund
        return true;
    }

    public boolean modifyReservation(Date newCheckInDate, Date newCheckOutDate) {
        this.checkInDate = newCheckInDate;
        this.checkOutDate = newCheckOutDate;
        // Logic to check availability and update reservation
        return true;
    }

    // Getters and setters can be added here for each field
}
2.2. Class: ReservationManager

import java.util.Date;

public class ReservationManager {

    public Reservation createReservation(int userId, int hotelId, int roomTypeId, Date checkInDate, Date checkOutDate) {
        // Logic to create a new reservation
        return new Reservation(generateReservationId(), userId, hotelId, roomTypeId, checkInDate, checkOutDate);
    }

    public boolean cancelReservation(int reservationId) {
        // Logic to cancel a reservation and update the status
        return true;
    }

    public boolean modifyReservation(int reservationId, Date newCheckInDate, Date newCheckOutDate) {
        // Logic to modify a reservation
        return true;
    }

    private int generateReservationId() {
        // Logic to generate a unique reservation ID
        return (int) (Math.random() * 10000);
    }
}

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3. Reviews and Ratings
3.1. Class: Review

import java.util.Date;

public class Review {
    private int reviewId;
    private int userId;
    private int hotelId;
    private int roomTypeId;
    private int rating; // e.g., 1-5 stars
    private String comment;
    private Date timestamp;

    public Review(int reviewId, int userId, int hotelId, int roomTypeId, int rating, String comment, Date timestamp) {
        this.reviewId = reviewId;
        this.userId = userId;
        this.hotelId = hotelId;
        this.roomTypeId = roomTypeId;
        this.rating = rating;
        this.comment = comment;
        this.timestamp = timestamp;
    }

    // Getters and setters can be added here for each field
}

3.2. Class: ReviewManager

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

public class ReviewManager {

    private List<Review> reviews = new ArrayList<>();

    public void submitReview(Review review) {
        reviews.add(review);
    }

    public void editReview(int reviewId, String newComment, int newRating) {
        for (Review review : reviews) {
            if (review.getReviewId() == reviewId) {
                review.setComment(newComment);
                review.setRating(newRating);
                break;
            }
        }
    }

    public void deleteReview(int reviewId) {
        reviews.removeIf(review -> review.getReviewId() == reviewId);
    }

    public List<Review> getHotelReviews(int hotelId) {
        List<Review> hotelReviews = new ArrayList<>();
        for (Review review : reviews) {
            if (review.getHotelId() == hotelId) {
                hotelReviews.add(review);
            }
        }
        return hotelReviews;
    }

    public double getAggregateRating(int hotelId) {
        List<Review> hotelReviews = getHotelReviews(hotelId);
        int totalRating = 0;
        for (Review review : hotelReviews) {
            totalRating += review.getRating();
        }
        return hotelReviews.size() == 0 ? 0 : (double) totalRating / hotelReviews.size();
    }
}

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4. Payment and Discounts
4.1. Class: Payment

public class Payment {
    private int paymentId;
    private int reservationId;
    private double amount;
    private String status; // e.g., Paid, Pending, Refunded
    private String paymentMethod; // e.g., Credit Card, PayPal
    private String transactionId;

    public Payment(int paymentId, int reservationId, double amount, String status, String paymentMethod, String transactionId) {
        this.paymentId = paymentId;
        this.reservationId = reservationId;
        this.amount = amount;
        this.status = status;
        this.paymentMethod = paymentMethod;
        this.transactionId = transactionId;
    }

    public boolean processPayment() {
        this.status = "Paid";
        // Logic to process the payment via integrated payment gateway
        return true;
    }

    public boolean refundPayment() {
        this.status = "Refunded";
        // Logic to process the refund
        return true;
    }

    // Getters and setters can be added here for each field
}
4.2. Class: Discount

import java.util.Date;
import java.util.List;

public class Discount {
    private int discountId;
    private String code;
    private String discountType; // e.g., Percentage, Fixed Amount
    private double discountValue;
    private Date validFrom;
    private Date validTo;
    private List<Integer> applicableHotelIds;
    private List<Integer> applicableRoomTypeIds;

    public Discount(int discountId, String code, String discountType, double discount