HotelReservationSystem.java

import java.io.*;
import java.util.*;

// ---------- Room Class ----------
class Room {
    int roomNumber;
    String category;
    boolean available;

    Room(int roomNumber, String category) {
        this.roomNumber = roomNumber;
        this.category = category;
        this.available = true;
    }
}

// ---------- Reservation Class ----------
class Reservation {
    String name;
    int roomNumber;
    String category;

    Reservation(String name, int roomNumber, String category) {
        this.name = name;
        this.roomNumber = roomNumber;
        this.category = category;
    }

    public String toFileString() {
        return name + "," + roomNumber + "," + category;
    }
}

// ---------- Main Class ----------
public class HotelReservationSystem {

    static ArrayList<Room> rooms = new ArrayList<>();
    static final String FILE_NAME = "reservations.txt";

    public static void main(String[] args) {

        initializeRooms();
        loadReservations();

        Scanner sc = new Scanner(System.in);
        int choice;

        do {
            System.out.println("\n===== HOTEL RESERVATION SYSTEM =====");
            System.out.println("1. Search Available Rooms");
            System.out.println("2. Book Room");
            System.out.println("3. Cancel Reservation");
            System.out.println("4. View Reservations");
            System.out.println("5. Exit");

            System.out.print("Enter choice: ");
            choice = sc.nextInt();
            sc.nextLine();

            switch (choice) {
                case 1:
                    searchRooms();
                    break;
                case 2:
                    bookRoom(sc);
                    break;
                case 3:
                    cancelReservation(sc);
                    break;
                case 4:
                    viewReservations();
                    break;
            }

        } while (choice != 5);

        System.out.println("Thank You!");
    }

    // ---------- Initialize Rooms ----------
    static void initializeRooms() {
        rooms.add(new Room(101, "Standard"));
        rooms.add(new Room(102, "Standard"));
        rooms.add(new Room(201, "Deluxe"));
        rooms.add(new Room(202, "Deluxe"));
        rooms.add(new Room(301, "Suite"));
    }

    // ---------- Search Rooms ----------
    static void searchRooms() {
        System.out.println("\nAvailable Rooms:");
        for (Room r : rooms) {
            if (r.available) {
                System.out.println("Room " + r.roomNumber + " - " + r.category);
            }
        }
    }

    // ---------- Book Room ----------
    static void bookRoom(Scanner sc) {

        System.out.print("Enter Customer Name: ");
        String name = sc.nextLine();

        searchRooms();

        System.out.print("Enter Room Number: ");
        int roomNo = sc.nextInt();

        for (Room r : rooms) {
            if (r.roomNumber == roomNo && r.available) {

                System.out.println("Processing Payment...");
                System.out.println("Payment Successful!");

                r.available = false;

                saveReservation(new Reservation(name, roomNo, r.category));

                System.out.println("Room Booked Successfully!");
                return;
            }
        }

        System.out.println("Room not available!");
    }

    // ---------- Cancel Reservation ----------
    static void cancelReservation(Scanner sc) {

        System.out.print("Enter Room Number to Cancel: ");
        int roomNo = sc.nextInt();

        for (Room r : rooms) {
            if (r.roomNumber == roomNo) {
                r.available = true;
                removeReservation(roomNo);
                System.out.println("Reservation Cancelled!");
                return;
            }
        }
    }

    // ---------- Save Reservation ----------
    static void saveReservation(Reservation res) {
        try (BufferedWriter bw = new BufferedWriter(new FileWriter(FILE_NAME, true))) {

            bw.write(res.toFileString());
            bw.newLine();

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    // ---------- View Reservations ----------
    static void viewReservations() {
        System.out.println("\nCurrent Reservations:");

        try (BufferedReader br = new BufferedReader(new FileReader(FILE_NAME))) {

            String line;
            while ((line = br.readLine()) != null) {
                String[] data = line.split(",");
                System.out.println("Name: " + data[0] +
                        " | Room: " + data[1] +
                        " | Category: " + data[2]);
            }

        } catch (Exception e) {
            System.out.println("No reservations found.");
        }
    }

    // ---------- Remove Reservation ----------
    static void removeReservation(int roomNo) {

        File input = new File(FILE_NAME);
        File temp = new File("temp.txt");

        try (BufferedReader br = new BufferedReader(new FileReader(input));
                BufferedWriter bw = new BufferedWriter(new FileWriter(temp))) {

            String line;

            while ((line = br.readLine()) != null) {
                if (!line.contains("," + roomNo + ",")) {
                    bw.write(line);
                    bw.newLine();
                }
            }

        } catch (Exception e) {
            e.printStackTrace();
        }

        input.delete();
        temp.renameTo(input);
    }

    // ---------- Load Reservations ----------
    static void loadReservations() {
        try (BufferedReader br = new BufferedReader(new FileReader(FILE_NAME))) {

            String line;

            while ((line = br.readLine()) != null) {
                String[] data = line.split(",");
                int roomNo = Integer.parseInt(data[1]);

                for (Room r : rooms) {
                    if (r.roomNumber == roomNo)
                        r.available = false;
                }
            }

        } catch (Exception e) {
            // first run -> file may not exist
        }
    }
}