/Amaap-OOMD

Unusual Spends

Description :

You work at a credit card company and as a value-add they want to start providing alerts to users when their spending in any particular category is higher than usual.

  • Compare the total amount paid for the current month, grouped by category with the previous month
  • Filter down to the categories for which the user spent at least 50% more this month than last month
  • Compose an e-mail message to the user that lists the categories for which spending was unusually high

OOMD Design for the Credit Card Company

class Customer

  • States :

    private String name; private String email;

  • Behaviour

    public Customer(String name, String email) public String getName() public String getEmail()

class CreditCardUser

  • States :

    -private final limit

class Transaction

  • States :

    • private enum Category
    • private Map<Category, Double> amountForEachCategory

  • Constructor:

    • Transaction(Map<Category, Double> amountForEachCategory)

  • Behaviour:

    • public double totalAmountSpent
    • public Map<Category, Double> groupByCategory()

class Transactions

  • States:

    • private List previousMonthTransactions
    • private List currentMonthTransactions

  • Constructor:

    • TransactionAnalyzer(List previousMonthTransactions, List currentMonthTransactions)

  • Behaviour:

    • public List getPreviousMonthTransactions()
    • public List getCurrentMonthTransactions()
    • public double totalAmountSpent()
    • public double totalAmountSpentInPreviousMonth()
    • private double totalAmount(List transactions)
    • public Map<Category, Double> totalAmountOfUnusualSpentPerCategory()
    • private double getPreviousMonthAmount

class UnusualSpendAnalyser

  • public boolean isUnusualSpending(Transactions transactions)

interface

  • void send(Notification notification)

class AlertSystem

  • EmailAlertMessage : message related all formats
  • EmailAlertSystem : actual implementation of the code to send email