Summary: Designing a Vending Machine

Now that you’ve completed the Vending Machine case study, let’s take a moment to reflect on and consolidate what we’ve learned. We’ll revisit the key system requirements, identify the core classes along with their responsibilities and relationships, and highlight the major design principles applied. We’ll also examine how objects interact within the system and walk through the overall workflow to understand how the components come together to achieve the desired functionality.

Key requirements

This section outlines the primary functional requirements that shaped the design of the vending machine system.

1. The machine must store and manage various products, with each item assigned to a unique slot.

2. The system operates in three distinct states: NoMoneyInsertedState, MoneyInsertedState, and DispenseState.

3. The system has two main actors: a Customer, who buys products, and an Operator, who manages the machine.

4. An Operator must be able to add or remove products from the machine’s inventory.

5. Users must be able to select a product by specifying its rack number.

6. Users can insert cash as payment.

7. The system must accurately calculate the total amount of money inserted.

8. The system must verify if the inserted amount is sufficient for the selected product.

9. If the user pays more than the product price, the system must dispense the product and return the correct change. ...