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Customer class and Admin class that will inherit the User class.
CreditCardPayment, DebitPayment, CashPayment, and ApplePayPayment will inherit the payment class.
Factory Design Patterns can be used to create payment objects
Attributes: For each class, define the attributes (data) it will hold...
Methods: Define the methods (functions) that operate on the attributes. Ensure they align with the object's responsibilities and adhere to the principle of encapsulation.
public class VendingMachine
{
private int _id;
private InventoryManagement inventory;
private Alert alert;
private Admin admin;
public VendingMachine()
{
InventoryManagement inventory = new InventoryManagement();
initializeInventory();
initializeAdmin();
}
private void initializeInventory()
{
inventory.add("abc", 1);
}
private void initializeInventory()
{
admin = new Admin(1);
}
public int showMenu()
{
System.out.println("Enter item id");
Scanner in = new Scanner(System.in);
String s = in.nextLine();
int itemId = Integer.parseInt(s);
return itemId;
}
public String showPaymentMthods()
{
System.out.println("Enter Payment method");
System.out.println("1. Credit Card 2. Debit Card 3. Apple Pay 4. Cash");
Scanner in = new Scanner(System.in);
String paymentMethod = in.nextLine();
return paymentMethod;
}
public boolean processPayment(String paymentType, int costToPay)
{
try{
Payment payment = PaymentFactory.createPayment(paymentType);
return payment.pay(costToPay)
}catch(PaymentException payEx)
{
System.out.println("Payment processing error");
}
public void dispenseItem(int itemId)
{
try
{
inventory.update(itemId);
}
catch(Exception ex)
{
System.out.println(ex.getMessage());
}
public boolean isItemAvailable(int itemId)
{
try
{
return inventory.search(itemId);
}catch(LowInventoryException ex)
{
alert.send("Low Inventory", adminId);
}
}
}
interface Payment {
boolean processPayment(double amount);
}
class CashPayment implements Payment {
@Override
public boolean processPayment(double amount) {
// Logic for processing cash payment
return true; // Assuming cash transaction is successful
}
}
class CardPayment implements Payment {
@Override
public boolean processPayment(double amount) {
// Logic for processing card payment
return true; // Assuming card transaction is successful
}
}
class MobilePayment implements Payment {
@Override
public boolean processPayment(double amount) {
// Logic for processing mobile payment
return true; // Assuming mobile transaction is successful
}
}
class PaymentFactory {
public static Payment createPayment(String paymentType) {
switch (paymentType.toLowerCase()) {
case "cash":
return new CashPayment();
case "card":
return new CardPayment();
case "mobile":
return new MobilePayment();
default:
throw new IllegalArgumentException("Invalid payment type");
}
}
}
class PaymentFactory {
public static Payment createPayment(String paymentType) {
switch (paymentType.toLowerCase()) {
case "cash":
return new CashPayment();
case "card":
return new CardPayment();
case "mobile":
return new MobilePayment();
default:
throw new IllegalArgumentException("Invalid payment type");
}
}
}
class MonitoringSystem
{
//check the health of vending machine
checkSystem(VendingMachine VM)
}
class InventoryManagement
{
List<Integer,Integer> itemsCost;
List<Integer,Integer> itemsQuantities;
public void add(int itemId, int cost)
// add item;
}
public void update(int itemId, int cost)
// update item;
}
public void delete(int itemId)
// delete item;
}
// Example
Check and explain whether your design adheres to solid principles (Ask interviewer what SOLID principle is if you can not recall it.)...
Single Responsibility - every class deals only with their responsibilities
O- Open Close Principle - they are open for extension and close for modification
L - child class inherits methods of base class and can be used interchangeably
I- No client should be forced to depend on methods it does not use - maybe more interfaces can be created
D - Dependency inversion principle - high level module should not depend on low level module - Inventory management and Payment can be added as external dependency
Explain how your design can handle changes in scale and whether it would be easily to extend with new functionalities...
It is flexible as it follows SOLID Principles
Currently, it handles only single-user request, to handle multiple, inventory lists should be handled in a synchronized class
Critically examine your design for any flaws or areas for future improvement...
To handle logging, analytics metrics, operational metrics and multiple requests