Travel Booking System -- Project Documentation

Version: 1.0
Language: Java (Core Java Only)
Architecture: Single-file OOP
File: Main.java
Author: Project Team
Date: April 2026

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Table of Contents

1. Project Overview
2. System Architecture
3. Class Diagram (UML)
4. Class Descriptions
5. Sequence Diagrams
6. Activity Diagrams
7. OOP Principles Demonstrated
8. Data Model
9. Application Flow
10. How to Run
11. Trade-offs & Future Scope

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1. Project Overview

The Travel Booking System is a fully interactive, colorful CLI application built entirely in Core Java inside a single file (Main.java). It simulates a real-world travel booking platform where users can:

• Register and Login with credentials
• Browse 5 predefined travel routes across India
• Select travel modes (Bus or Flight) with real pricing
• Choose from 5 rich day-wise itineraries (3 to 7 days) per route
• Book seats and see a full price breakdown
• Pay via UPI PIN validation
• View all past bookings

Key Features

Feature	Description
Authentication	Register with name, email, password, phone, UPI PIN. Login via email + password
Routes	5 fixed routes: Delhi-Goa, Mumbai-Manali, Bangalore-Kerala, Chennai-Andaman, Hyderabad-Rajasthan
Travel Modes	Bus (AC Sleeper, Non-AC, Semi-Sleeper) and Flight (Economy, Business) per route
Itineraries	5 day-wise itineraries per route (3-day through 7-day) with detailed plans
Booking	Seat selection, price calculation, UPI payment, booking confirmation
CLI Design	ANSI colored output with ASCII-safe formatting for Windows compatibility

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2. System Architecture

The system follows a layered architecture even within a single file:

graph TD
    subgraph Presentation["Presentation Layer"]
        MAIN["Main (Entry Point + Static Banner)"]
        APP["TravelApp (CLI Controller)"]
        COLOR["Color (ANSI Utility)"]
    end

    subgraph Service["Service Layer"]
        AUTH["AuthService"]
        BOOK["BookingService"]
        PAY["UPIPayment"]
    end

    subgraph Data["Data Layer"]
        DS["DataStore (Static Routes + Modes)"]
        IG["ItineraryGenerator (Static Itinerary Data)"]
    end

    subgraph Model["Model Layer"]
        USER["User"]
        ROUTE["Route"]
        TM["TravelMode (Abstract)"]
        BUS["Bus"]
        FLT["Flight"]
        ITIN["Itinerary"]
        BKG["Booking"]
    end

    subgraph Contract["Interfaces"]
        PS["PaymentService"]
        DISP["Displayable"]
    end

    MAIN --> APP
    APP --> AUTH
    APP --> BOOK
    APP --> PAY
    APP --> DS
    APP --> IG
    PAY -.->|implements| PS
    ROUTE -.->|implements| DISP
    TM -.->|implements| DISP
    ITIN -.->|implements| DISP
    BKG -.->|implements| DISP
    BUS -->|extends| TM
    FLT -->|extends| TM

    style Presentation fill:#1a1a2e,color:#e94560
    style Service fill:#16213e,color:#0f3460
    style Data fill:#0f3460,color:#53354a
    style Model fill:#533483,color:#e94560
    style Contract fill:#2b2d42,color:#8d99ae

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Layer Responsibilities

Layer	Classes	Responsibility
Presentation	Main, TravelApp, Color	Entry point, menu rendering, user interaction, ANSI formatting
Service	AuthService, BookingService, UPIPayment	Business logic: auth, booking, payment
Data	DataStore, ItineraryGenerator	Pre-loaded route/mode/itinerary data via static blocks
Model	User, Route, TravelMode, Bus, Flight, Itinerary, Booking	Domain entities with encapsulation
Interfaces	PaymentService, Displayable	Contracts for abstraction and polymorphism

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3. Class Diagram (UML)

classDiagram
    class Main {
        +static main(String[] args)
    }

    class Color {
        +static String RESET
        +static String RED
        +static String GREEN
        +static String YELLOW
        +static String BLUE
        +static String PURPLE
        +static String CYAN
        +static String CYAN_BOLD
        +static String WHITE_BOLD
        +static String DIM
        +static void success(String msg)
        +static void error(String msg)
        +static void warn(String msg)
        +static void info(String msg)
        +static void header(String title)
        +static void menuItem(int num, String text)
        +static void divider()
        +static String prompt(String label)
        +static void price(String label, double amount)
    }

    class Displayable {
        <<interface>>
        +display() void
    }

    class PaymentService {
        <<interface>>
        +processPayment(User user, double amount, Scanner scanner) boolean
        +getPaymentMethod() String
    }

    class BookingException {
        +BookingException(String message)
    }

    class User {
        -String name
        -String email
        -String password
        -String phone
        -String upiPin
        +getName() String
        +getEmail() String
        +getPassword() String
        +getPhone() String
        +getUpiPin() String
        +validatePassword(String input) boolean
        +validateUpiPin(String input) boolean
    }

    class Route {
        -int id
        -String source
        -String destination
        -List~String~ attractions
        +getId() int
        +getSource() String
        +getDestination() String
        +getAttractions() List~String~
        +display() void
        +toString() String
    }

    class TravelMode {
        <<abstract>>
        -String name
        -double pricePerSeat
        -int seatsAvailable
        +getName() String
        +getPricePerSeat() double
        +getSeatsAvailable() int
        +hasSeats(int count) boolean
        +reserveSeats(int count) void
        +getModeType()* String
        +getModeTag()* String
        +display() void
    }

    class Bus {
        -String busType
        +getBusType() String
        +getModeType() String
        +getModeTag() String
    }

    class Flight {
        -String airlineClass
        +getAirlineClass() String
        +getModeType() String
        +getModeTag() String
    }

    class Itinerary {
        -int days
        -List~String~ dayPlans
        -List~String~ destinations
        -double price
        +getDays() int
        +getDayPlans() List~String~
        +getDestinations() List~String~
        +getPrice() double
        +display() void
        +toSummary() String
    }

    class Booking {
        -static int counter
        -String bookingId
        -String userEmail
        -Route route
        -TravelMode travelMode
        -Itinerary itinerary
        -int seatsBooked
        -double totalPrice
        -Date bookingDate
        +getUserEmail() String
        +getBookingId() String
        +getRoute() Route
        +getTravelMode() TravelMode
        +getItinerary() Itinerary
        +getSeatsBooked() int
        +getTotalPrice() double
        +display() void
    }

    class AuthService {
        -Map~String,User~ userStore
        +register(String, String, String, String, String) boolean
        +login(String email, String password) User
    }

    class UPIPayment {
        +processPayment(User, double, Scanner) boolean
        +getPaymentMethod() String
    }

    class BookingService {
        -List~Booking~ bookings
        +createBooking(String, Route, TravelMode, Itinerary, int) Booking
        +confirmBooking(Booking, TravelMode) void
        +getUserBookings(String userEmail) List~Booking~
    }

    class ItineraryGenerator {
        -static Map~Integer,List~ ROUTE_ATTRACTIONS
        -static Map~Integer,List~ ROUTE_DAY_ACTIVITIES
        +static generate(Route) List~Itinerary~
    }

    class DataStore {
        +static List~Route~ ROUTES
        +static Map~Integer,List~ TRAVEL_MODES
        +static getRouteById(int) Route
        +static getModesForRoute(int) List~TravelMode~
    }

    class TravelApp {
        -Scanner scanner
        -AuthService authService
        -BookingService bookingService
        -PaymentService paymentService
        -User currentUser
        +run() void
        -showAuthMenu() void
        -doRegister() void
        -doLogin() void
        -showMainMenu() void
        -viewRoutes() void
        -makeBooking() void
        -showMyBookings() void
    }

    BookingException --|> Exception
    TravelMode ..|> Displayable
    Route ..|> Displayable
    Itinerary ..|> Displayable
    Booking ..|> Displayable
    UPIPayment ..|> PaymentService
    Bus --|> TravelMode
    Flight --|> TravelMode

    Main --> TravelApp : creates
    TravelApp --> AuthService : uses
    TravelApp --> BookingService : uses
    TravelApp --> PaymentService : uses
    TravelApp --> DataStore : reads
    TravelApp --> ItineraryGenerator : generates
    TravelApp --> Color : formats output

    Booking *-- Route : contains
    Booking *-- TravelMode : contains
    Booking *-- Itinerary : contains
    AuthService o-- User : stores
    BookingService o-- Booking : stores
    DataStore o-- Route : stores
    DataStore o-- TravelMode : stores

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4. Class Descriptions

4.1 Interfaces

Interface	Methods	Purpose
Displayable	display()	Common contract for all entities that can render themselves to CLI
PaymentService	processPayment(), getPaymentMethod()	Abstraction for payment processing; allows swapping UPI for Card, etc.

4.2 Abstract Class

Class	Extends	Purpose
TravelMode	-- (implements Displayable)	Base class for all travel options. Holds shared fields (name, price, seats) and seat management logic. Forces subclasses to define getModeType() and getModeTag()

4.3 Concrete Models

Class	Key Fields	Role
User	name, email, password, phone, upiPin	Immutable user profile with validation methods
Route	id, source, destination, attractions	Travel route with scenic attractions
Bus	busType (AC Sleeper, Non-AC)	Extends TravelMode for bus travel
Flight	airlineClass (Economy, Business)	Extends TravelMode for air travel
Itinerary	days (3-7), dayPlans, destinations, price	Day-wise travel plan with pricing
Booking	bookingId, route, mode, itinerary, seats, totalPrice, date	Complete booking record
BookingException	message	Custom checked exception for booking errors

4.4 Services

Class	Implements	Responsibility
AuthService	--	User registration with validation, login with credential checking
BookingService	--	Create bookings, validate seat availability, confirm + store bookings
UPIPayment	PaymentService	Validate UPI PIN against stored user PIN, simulate payment delay
ItineraryGenerator	--	Generate 5 route-specific itineraries per route from static data
DataStore	--	Static storage of 5 routes and their travel modes

4.5 Presentation

Class	Role
Main	Entry point with static block for ASCII banner
TravelApp	Main application loop, menu rendering, full booking flow orchestration
Color	ANSI escape code constants and formatted output helpers

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5. Sequence Diagrams

5.1 User Registration Flow

sequenceDiagram
    participant U as User (CLI)
    participant TA as TravelApp
    participant AS as AuthService
    participant UM as User Model

    U->>TA: Select "Register" from Auth Menu
    TA->>U: Prompt for Name
    U->>TA: Enter "John Doe"
    TA->>U: Prompt for Email
    U->>TA: Enter "john@mail.com"
    TA->>U: Prompt for Password
    U->>TA: Enter "pass123"
    TA->>U: Prompt for Phone
    U->>TA: Enter "9876543210"
    TA->>U: Prompt for UPI PIN
    U->>TA: Enter "1234"

    TA->>AS: register(name, email, pass, phone, pin)
    AS->>AS: Validate email format
    AS->>AS: Check duplicate email
    AS->>AS: Validate password length >= 4
    AS->>AS: Validate UPI PIN is 4 digits
    AS->>AS: Validate phone length >= 10
    AS->>UM: new User(name, email, pass, phone, pin)
    UM-->>AS: User object created
    AS->>AS: userStore.put(email, user)
    AS-->>TA: return true
    TA->>U: Display "[OK] Registration successful!"

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5.2 User Login Flow

sequenceDiagram
    participant U as User (CLI)
    participant TA as TravelApp
    participant AS as AuthService

    U->>TA: Select "Login" from Auth Menu
    TA->>U: Prompt for Email
    U->>TA: Enter "john@mail.com"
    TA->>U: Prompt for Password
    U->>TA: Enter "pass123"

    TA->>AS: login(email, password)
    AS->>AS: userStore.get(email)
    
    alt User not found
        AS-->>TA: return null
        TA->>U: Display "[X] No account found"
    else User found
        AS->>AS: user.validatePassword(password)
        alt Password incorrect
            AS-->>TA: return null
            TA->>U: Display "[X] Incorrect password"
        else Password correct
            AS-->>TA: return User object
            TA->>TA: currentUser = user
            TA->>U: Display "[OK] Welcome back, John Doe!"
        end
    end

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5.3 Complete Booking Flow

sequenceDiagram
    participant U as User (CLI)
    participant TA as TravelApp
    participant DS as DataStore
    participant IG as ItineraryGenerator
    participant BS as BookingService
    participant PS as UPIPayment
    participant TM as TravelMode

    Note over U,TM: STEP 1: Route Selection
    TA->>DS: DataStore.ROUTES
    DS-->>TA: List of 5 Routes
    TA->>U: Display all routes
    U->>TA: Select Route ID (e.g., 3)
    TA->>DS: getRouteById(3)
    DS-->>TA: Route "Bangalore -> Kerala"

    Note over U,TM: STEP 2: Travel Mode Selection
    TA->>DS: getModesForRoute(3)
    DS-->>TA: List of TravelModes (Flights + Buses)
    TA->>U: Display all modes with prices & seats
    U->>TA: Select mode (e.g., 1 = IndiGo Economy)

    Note over U,TM: STEP 3: Itinerary Selection
    TA->>IG: ItineraryGenerator.generate(route)
    IG-->>TA: 5 Itineraries (3-day to 7-day)
    TA->>U: Display all 5 itineraries with day-wise plans
    U->>TA: Select itinerary (e.g., 3 = 5-Day)

    Note over U,TM: STEP 4: Seat Selection & Payment
    U->>TA: Enter number of seats (e.g., 2)
    TA->>BS: createBooking(email, route, mode, itinerary, 2)
    BS->>BS: Validate seats > 0
    BS->>TM: mode.hasSeats(2)
    TM-->>BS: true
    BS->>BS: totalPrice = 2 * (3200 + 5000) = Rs.16400
    BS-->>TA: Booking object (not yet confirmed)

    TA->>U: Display price breakdown
    TA->>PS: processPayment(user, 16400, scanner)
    PS->>U: Prompt for UPI PIN
    U->>PS: Enter "1234"
    PS->>PS: user.validateUpiPin("1234")
    PS->>PS: Simulate processing delay
    PS-->>TA: return true (payment success)

    TA->>BS: confirmBooking(booking, mode)
    BS->>TM: mode.reserveSeats(2)
    TM->>TM: seatsAvailable -= 2
    BS->>BS: bookings.add(booking)
    BS-->>TA: Booking confirmed

    TA->>U: Display Booking confirmation card

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5.4 View Bookings Flow

sequenceDiagram
    participant U as User (CLI)
    participant TA as TravelApp
    participant BS as BookingService

    U->>TA: Select "Show My Bookings"
    TA->>BS: getUserBookings(currentUser.email)
    BS->>BS: Filter bookings by email
    BS-->>TA: List of user's bookings

    alt No bookings
        TA->>U: Display "[!] No bookings yet"
    else Has bookings
        TA->>U: Display total count
        loop For each booking
            TA->>U: Display booking card with ID, route, mode, itinerary, seats, price, date
        end
    end

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---

6. Activity Diagrams

6.1 Application Main Flow

flowchart TD
    START([Application Start]) --> BANNER[Display ASCII Banner via Static Block]
    BANNER --> CHECK{User Logged In?}

    CHECK -->|No| AUTH_MENU[Show Auth Menu]
    AUTH_MENU --> AUTH_CHOICE{Choice?}

    AUTH_CHOICE -->|1 - Login| LOGIN[Prompt Email + Password]
    LOGIN --> VALIDATE_LOGIN{Credentials Valid?}
    VALIDATE_LOGIN -->|Yes| SET_USER[Set currentUser]
    SET_USER --> CHECK
    VALIDATE_LOGIN -->|No| ERR1[Show Error Message]
    ERR1 --> CHECK

    AUTH_CHOICE -->|2 - Register| REGISTER[Prompt Name, Email, Pass, Phone, PIN]
    REGISTER --> VALIDATE_REG{All Validations Pass?}
    VALIDATE_REG -->|Yes| STORE_USER[Store User in HashMap]
    STORE_USER --> SUC1[Show Success Message]
    SUC1 --> CHECK
    VALIDATE_REG -->|No| ERR2[Show Validation Error]
    ERR2 --> CHECK

    AUTH_CHOICE -->|3 - Exit| EXIT_APP([Exit Application])

    CHECK -->|Yes| MAIN_MENU[Show Main Menu]
    MAIN_MENU --> MAIN_CHOICE{Choice?}

    MAIN_CHOICE -->|1| VIEW_ROUTES[Display All 5 Routes]
    VIEW_ROUTES --> CHECK

    MAIN_CHOICE -->|2| BOOKING_FLOW[Start Booking Flow]
    BOOKING_FLOW --> CHECK

    MAIN_CHOICE -->|3| VIEW_BOOKINGS[Display User's Bookings]
    VIEW_BOOKINGS --> CHECK

    MAIN_CHOICE -->|4| LOGOUT[Set currentUser = null]
    LOGOUT --> CHECK

    style START fill:#2ecc71,color:#fff
    style EXIT_APP fill:#e74c3c,color:#fff
    style BANNER fill:#9b59b6,color:#fff
    style AUTH_MENU fill:#3498db,color:#fff
    style MAIN_MENU fill:#3498db,color:#fff

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6.2 Booking Flow Activity Diagram

flowchart TD
    START([Make Booking Selected]) --> SHOW_ROUTES[Display All Routes]
    SHOW_ROUTES --> INPUT_ROUTE[/User Enters Route ID/]
    INPUT_ROUTE --> VALID_ROUTE{Valid Route ID?}

    VALID_ROUTE -->|No| ERR_ROUTE[Show Error, Return to Menu]
    ERR_ROUTE --> END_FAIL([Return to Main Menu])

    VALID_ROUTE -->|Yes| SHOW_MODES[Display Travel Modes for Route]
    SHOW_MODES --> INPUT_MODE[/User Selects Travel Mode/]
    INPUT_MODE --> VALID_MODE{Valid Mode?}

    VALID_MODE -->|No| ERR_MODE[Show Error, Return to Menu]
    ERR_MODE --> END_FAIL

    VALID_MODE -->|Yes| GEN_ITIN[Generate 5 Itineraries for Route]
    GEN_ITIN --> SHOW_ITIN[Display All Itineraries with Day Plans]
    SHOW_ITIN --> INPUT_ITIN[/User Selects Itinerary/]
    INPUT_ITIN --> VALID_ITIN{Valid Itinerary?}

    VALID_ITIN -->|No| ERR_ITIN[Show Error, Return to Menu]
    ERR_ITIN --> END_FAIL

    VALID_ITIN -->|Yes| INPUT_SEATS[/User Enters Number of Seats/]
    INPUT_SEATS --> VALID_SEATS{Seats > 0 AND Available?}

    VALID_SEATS -->|No| ERR_SEATS[Show Error via BookingException]
    ERR_SEATS --> END_FAIL

    VALID_SEATS -->|Yes| CALC_PRICE[Calculate Total Price]
    CALC_PRICE --> SHOW_BREAKDOWN[Display Price Breakdown]
    SHOW_BREAKDOWN --> UPI_PIN[/User Enters UPI PIN/]
    UPI_PIN --> VALIDATE_PIN{PIN Correct?}

    VALIDATE_PIN -->|No| PAY_FAIL[Payment Failed Message]
    PAY_FAIL --> END_FAIL

    VALIDATE_PIN -->|Yes| PAY_SUCCESS[Payment Success]
    PAY_SUCCESS --> RESERVE[Reserve Seats on TravelMode]
    RESERVE --> STORE_BOOKING[Store Booking in BookingService]
    STORE_BOOKING --> CONFIRM[Display Booking Confirmation Card]
    CONFIRM --> END_OK([Return to Main Menu])

    style START fill:#2ecc71,color:#fff
    style END_OK fill:#2ecc71,color:#fff
    style END_FAIL fill:#e74c3c,color:#fff
    style CALC_PRICE fill:#f39c12,color:#fff
    style PAY_SUCCESS fill:#27ae60,color:#fff
    style PAY_FAIL fill:#c0392b,color:#fff

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6.3 Payment Processing Activity Diagram

flowchart TD
    START([Payment Initiated]) --> SHOW_AMOUNT[Display Amount Due]
    SHOW_AMOUNT --> PROMPT_PIN[/Prompt for UPI PIN/]
    PROMPT_PIN --> CHECK_EMPTY{PIN Empty?}

    CHECK_EMPTY -->|Yes| THROW[Throw BookingException]
    THROW --> FAIL([Payment Failed])

    CHECK_EMPTY -->|No| SIMULATE[Simulate Processing Delay -- 1.5s]
    SIMULATE --> VALIDATE{PIN matches stored PIN?}

    VALIDATE -->|Yes| SUCCESS[Display Payment Success]
    SUCCESS --> RETURN_TRUE([Return true])

    VALIDATE -->|No| INCORRECT[Display Incorrect PIN Error]
    INCORRECT --> RETURN_FALSE([Return false])

    style START fill:#3498db,color:#fff
    style RETURN_TRUE fill:#2ecc71,color:#fff
    style RETURN_FALSE fill:#e74c3c,color:#fff
    style FAIL fill:#e74c3c,color:#fff
    style SIMULATE fill:#f39c12,color:#fff

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6.4 Registration Validation Activity Diagram

flowchart TD
    START([Registration Request]) --> V1{Email blank?}
    V1 -->|Yes| E1[Error: Email cannot be empty]
    E1 --> FAIL([Return false])

    V1 -->|No| V2{Email contains @ and .?}
    V2 -->|No| E2[Error: Invalid email format]
    E2 --> FAIL

    V2 -->|Yes| V3{Email already registered?}
    V3 -->|Yes| E3[Error: Account exists]
    E3 --> FAIL

    V3 -->|No| V4{Password length >= 4?}
    V4 -->|No| E4[Error: Password too short]
    E4 --> FAIL

    V4 -->|Yes| V5{UPI PIN is 4 digits?}
    V5 -->|No| E5[Error: Invalid UPI PIN]
    E5 --> FAIL

    V5 -->|Yes| V6{Phone length >= 10?}
    V6 -->|No| E6[Error: Invalid phone]
    E6 --> FAIL

    V6 -->|Yes| CREATE[Create User Object]
    CREATE --> STORE[Store in HashMap]
    STORE --> SUCCESS([Return true])

    style START fill:#3498db,color:#fff
    style SUCCESS fill:#2ecc71,color:#fff
    style FAIL fill:#e74c3c,color:#fff

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---

7. OOP Principles Demonstrated

7.1 Encapsulation

All model classes use private final fields with public getters only. No direct field access is allowed from outside the class.

User:
  - private final String name       --> getName()
  - private final String email      --> getEmail()
  - private final String upiPin     --> validateUpiPin() (no direct getter exposure for PIN)

TravelMode:
  - private int seatsAvailable      --> managed internally via reserveSeats() and hasSeats()

Key design: User.validateUpiPin() hides the comparison logic internally -- callers never see the raw PIN value.

7.2 Abstraction

Mechanism	Example
Interface	PaymentService defines what payment does (processPayment, getPaymentMethod) without how
Interface	Displayable defines that entities can render themselves, hiding implementation
Abstract Class	TravelMode provides shared seat management but forces subclasses to define mode-specific labels

7.3 Inheritance

TravelMode (abstract)
    |
    +-- Bus      (adds: busType field, overrides getModeType/getModeTag)
    +-- Flight   (adds: airlineClass field, overrides getModeType/getModeTag)

Bus and Flight inherit:

• name, pricePerSeat, seatsAvailable fields
• hasSeats(), reserveSeats() methods
• display() rendering logic

But provide their own:

• getModeType() -- returns "Bus (AC Sleeper)" vs "Flight (Economy)"
• getModeTag() -- returns "[BUS]" vs "[FLY]"

7.4 Polymorphism

Type	Where Used
Runtime (Method Overriding)	Bus.getModeType() and Flight.getModeType() called via TravelMode reference in booking flow
Runtime (Interface)	UPIPayment.processPayment() called via PaymentService reference in TravelApp
Runtime (Displayable)	Route.display(), Itinerary.display(), Booking.display() all called through Displayable contract

Example in code:

// TravelApp holds PaymentService reference (interface)
private final PaymentService paymentService = new UPIPayment();
// Can be swapped to: new CardPayment() without changing TravelApp

7.5 Collections Framework Usage

Collection	Class	Purpose
HashMap<String, User>	AuthService	User storage keyed by email for O(1) lookup
ArrayList<Booking>	BookingService	Ordered list of all bookings
ArrayList<Route>	DataStore	List of predefined routes
HashMap<Integer, List<TravelMode>>	DataStore	Route ID -> available travel modes mapping
HashMap<Integer, List<List<String>>>	ItineraryGenerator	Route ID -> attraction/activity data

7.6 Static Blocks

Class	Static Block Purpose
Main	Display ASCII art banner on class loading
DataStore	Initialize 5 routes and their travel modes
ItineraryGenerator	Load route-specific attraction and activity data for all 5 routes

7.7 Exception Handling

Exception	Where
BookingException (custom checked)	Seat unavailable, empty UPI PIN, invalid seat count
InputMismatchException	Non-numeric input where int expected
IllegalArgumentException	Itinerary days outside 3-7 range
Exception (catch-all)	Safety net in main loop

---

8. Data Model

8.1 Routes

ID	Source	Destination	Key Attractions
1	Delhi	Goa	Baga Beach, Fort Aguada, Dudhsagar Falls
2	Mumbai	Manali	Solang Valley, Rohtang Pass, Hadimba Temple
3	Bangalore	Kerala	Alleppey Backwaters, Munnar, Fort Kochi
4	Chennai	Andaman	Radhanagar Beach, Cellular Jail, Ross Island
5	Hyderabad	Rajasthan	Amber Fort, Sam Sand Dunes, Lake Pichola

8.2 Travel Modes per Route

Route	Mode	Operator	Price/Seat	Seats
Delhi-Goa	Flight (Economy)	Air India Express	Rs.4500	120
Delhi-Goa	Flight (Business)	IndiGo Airlines	Rs.5200	80
Delhi-Goa	Bus (AC Sleeper)	RedBus Volvo	Rs.1800	40
Delhi-Goa	Bus (Non-AC)	RSRTC Deluxe	Rs.1200	50
Mumbai-Manali	Flight (Economy)	SpiceJet	Rs.5800	100
Mumbai-Manali	Flight (Business)	Vistara	Rs.8500	60
Mumbai-Manali	Bus (AC Sleeper)	HRTC Volvo	Rs.2200	36
Mumbai-Manali	Bus (Semi-Sleeper)	Private Travels	Rs.1500	44
Bangalore-Kerala	Flight (Economy)	IndiGo	Rs.3200	150
Bangalore-Kerala	Bus (AC Sleeper)	KSRTC Airavat	Rs.1400	48
Chennai-Andaman	Flight (Economy)	GoAir	Rs.5500	90
Chennai-Andaman	Flight (Business)	Air India	Rs.9200	40
Hyderabad-Rajasthan	Flight (Economy)	IndiGo	Rs.4800	110
Hyderabad-Rajasthan	Bus (AC Sleeper)	SRS Travels	Rs.2000	38

Note

Chennai-Andaman has no bus options since Andaman is an island -- only flights are available.

8.3 Itinerary Pricing

Duration	Price
3-Day	Rs.2500
4-Day	Rs.3500
5-Day	Rs.5000
6-Day	Rs.6500
7-Day	Rs.8500

8.4 Total Price Formula

TOTAL PRICE = number_of_seats * (travel_price_per_seat + itinerary_price)

Example: 2 seats on IndiGo Economy (Rs.3200) + 5-Day Kerala itinerary (Rs.5000)

= 2 * (3200 + 5000) = Rs.16,400.00

---

9. Application Flow

9.1 State Diagram

stateDiagram-v2
    [*] --> NotLoggedIn : App starts, banner displays

    state NotLoggedIn {
        [*] --> AuthMenu
        AuthMenu --> Login : Option 1
        AuthMenu --> Register : Option 2
        AuthMenu --> [*] : Option 3 (Exit)
        Login --> AuthMenu : Failed
        Register --> AuthMenu : Complete
    }

    NotLoggedIn --> LoggedIn : Login Success

    state LoggedIn {
        [*] --> MainMenu
        MainMenu --> ViewRoutes : Option 1
        MainMenu --> MakeBooking : Option 2
        MainMenu --> ShowBookings : Option 3
        ViewRoutes --> MainMenu
        ShowBookings --> MainMenu

        state MakeBooking {
            [*] --> SelectRoute
            SelectRoute --> SelectMode : Valid route
            SelectMode --> SelectItinerary : Valid mode
            SelectItinerary --> SelectSeats : Valid itinerary
            SelectSeats --> Payment : Valid seats
            Payment --> BookingConfirmed : PIN correct
            Payment --> BookingFailed : PIN wrong
        }
        MakeBooking --> MainMenu
    }

    LoggedIn --> NotLoggedIn : Logout (Option 4)

Loading

9.2 Error Handling Flow

All exceptions in the main loop are caught gracefully:

TravelApp.run()
  |
  +-- try { showAuthMenu() / showMainMenu() }
  |
  +-- catch BookingException     --> Color.error(message)
  +-- catch InputMismatchException --> Color.error("Invalid input") + scanner.nextLine()
  +-- catch Exception            --> Color.error("Something went wrong: " + message)
  |
  +-- Loop continues (app never crashes)

---

10. How to Run

Prerequisites

• Java JDK 11 or higher installed
• Terminal that supports ANSI escape codes (Windows Terminal, PowerShell, VS Code Terminal)

Steps

# 1. Navigate to project directory
cd c:\Users\mdmeh\khamma\Travel_Booking_System

# 2. Compile
javac Main.java

# 3. Run
java Main

Expected Output on Launch

  ######################################################
  #                                                    #
  #        T R A V E L   B O O K I N G               #
  #              S Y S T E M                          #
  #                                                    #
  ######################################################
        Powered by Core Java | OOP Architecture

  ######################################################
  #           WELCOME -- TRAVEL BOOKING SYSTEM
  ######################################################
    [1] Login
    [2] Register
    [3] Exit

  >> Choose option:

---

11. Trade-offs & Future Scope

11.1 Single-File Trade-offs

Aspect	Current (Single File)	Multi-File (Future)
Compilation	javac Main.java -- one command	Build tool (Maven/Gradle) needed
Readability	Sectioned with comments, ~1000 lines	Each class in own file
Testability	Cannot unit-test classes independently	JUnit per class
IDE Navigation	Basic search	Full package navigation
Deployment	Copy one file	JAR with manifest

Important

Despite the single-file constraint, every class is fully self-contained. To migrate to multi-file, simply move each class to its own .java file and add package declarations -- zero logic changes needed.

11.2 Extension Points

Extension	How
New payment method	Implement PaymentService interface (e.g., CardPayment)
New travel mode	Extend TravelMode abstract class (e.g., Train, Cab)
New routes	Add entries to DataStore static block
Persistence	Replace HashMap/ArrayList with file I/O or database
Search/Filter	Add methods to DataStore for price range, destination filters
Cancellation	Add cancelBooking() to BookingService + refund in TravelMode.releaseSeats()