A LLD implementation of real world parking lot management system using OOPS, SOLID principles and Design patterns.

Design a Parking Lot System with following Requirements:

• Have Entry and Exit gate.
  
• Have multiple floors in the parking lot.
  
• Vehicles Allowed : Motorcycle, Cars, Trucks, Vans.
  
• Four types of parking spots based on Vehicle Type.
  
• Disallow vehicle entry if parking lot reaches full capacity.
  
• A vehicle can be parked only at the spot for its vehicle type.
  
• Generate parking tickets with duration tracking.
  
• Payment methods : Cash, Credit Card and UPI.
  
• Parking charges based on Hourly Rate.
  
  

• ParkingLot.java: Manages floors, entry gates, exit gates, and parking spot booking. A singleton class.
  
• ParkingFloor.java: Manages parking spots and updates its availability.
  
• ParkingSpot.java: Abstract representation of a parking spot.
  
• BikeParkingSpot.java, CarParkingSpot.java, OtherParkingSpot.java: Specific implementations for parking spots.
  
• Ticket.java: Represents a parking ticket issued to a vehicle.
  

• Vehicle.java: Abstract class for vehicles.
  
• BikeVehicle.java, CarVehicle.java, OtherVehicle.java: Specific implementations for vehicles.
  
• VehicleFactory.java: Factory class to create vehicle instances based on vehicle type.
  

• Payment.java: Manages payment logic.
  
• PaymentStrategy.java: Strategy pattern for payment processing.
  
• PaymentService.java: Selects and execute the appropriate payment strategy. A singleton class.
  
• CashPayment.java, CreditCardPayment.java, UPIPayment.java: Specific implementations for payment methods.
  

• EntranceGate.java: Handles vehicle entry, ticket generation, and parking spot allocation.
  
• ExitGate.java: Manages vehicle exit, calculates parking fees, and initiates payment processing.
  

• Entry point of application. Contains the main method to initialise and run the parking lot system.
  
  

• It provides a way to create objects without exposing the instantiation logic to the client. It promotes loose coupling by delegating the object creation to a specific class.
  
• In this project, VehicleFactory is used to create instances of different types of vehicles (Bike, Car, Van, Truck) based on parking requirement.
  
• Advantage - Extensibility & Loose Coupling.
  

• It is used to define a group of interchangeable algorithms and choose one at runtime.
  
• In this project, PaymentStrategy is used to support multiple payment methods like Cash, CreditCard, UPI. PaymentService uses the chosen one at runtime.
  
• Advantage - Flexible & Interchangeable logic.
  

• It ensures that only one instance of the class is created in the entire application. Must handle Multithreading case.
  
• In this project, PaymentService & ParkingLot is implemented as Singleton class to maintain a single instance of it across the system.
  
• Advantage - Shared instance, Global access.
  
  

1. Prerequisites:
   

• Java 17 or later installed.
  
• VS Code (recommended) or any Java-supported IDE.
  

2. Clone the Repository:
   

git clone https://github.com/Ansh2625/Parking-Lot-System.git 
cd Parking-Lot-System

3. Import the Project:
   

• Open VS Code.
  
• Select File > Open and choose the project's root folder (Parking-Lot-System).
  

4. Build the Project:
   

• Open Main.java file inside src.
  
• Click the Run button on top, or right-click and choose Run java.
  

5. Run the Application:
   

• Right-click on Main.java.
  
• Alternatively, use the terminal:
  

javac -d bin src/Main.java 
java -cp bin Main

6. Interact with the System:
   

• The system simulates parking operations.
  
• Check console logs for actions like ticket generation, parking spot allocation, and payments.
  
  

• Input File: Testcase.txt
  
• Output File: Sample_Output.txt
  
  

• Multi-floor parking lot with entry and exit gates.
  
• Support different parking spot types (Bike, Car, Van and Truck).
  
• Dynamic Parking spot allocation.
  
• Ticket generation for parked vehicles.
  
• Payment processing via Cash, CrediCard, or UPI.
  
• Easily extendable and modular codebase.
  
  

• Add new Vehicle Types: Create a new class extending Vehicle.java.
  
• Add new Payment Methods: Implement the PaymentStrategy.java interface.
  
• Duration Calculation: Use a Map<ParkingSpot,Ticket> to store tickets and calculate the duration automatically at exit gate instead of asking the user.
  
  

This project is open-source and available under the MIT License.

Developed by Ansh Sharma. Contact, anshsharma2625@gmail.com.