Exercises

Subject 1

Suppose you have a class Order with the following attributes:

• date: a date representing the date the order was placed.
• amount: a decimal representing the total amount of the order.
• customer: the name of the customer who placed the order.
• items: a collection of OrderItem objects representing the items in the order.

The OrderItem class has the following attributes:

• product: a reference to the product being ordered.
• quantity: an integer representing the quantity of the product being ordered.
• price: a decimal representing the cost of the product.

Questions

1. Represent the UML class diagram.
2. Write OCL expressions that satisfy the following requirements::

a. An operation that calculates the total quantity of items in an order.
b. A constraint that ensures that the total amount of an order is greater than 0.
c. A query that returns the most expensive product in an order.
d. A constraint that ensures that the order date is not in the future.
e. A query that returns the total amount of an order including tax.
NB. Note that TaxRate is a separate class with a static operation getRate(customer: Customer) : Decimal that returns the tax rate for a given customer.