See the UML diagram that goes along with this project. You must follow it $100\%,$ that include all the names used, parameters $($amounts and types$)$ etc.

Overall

The overall concept of this project is a point of sales program. The customer can purchase any items that are currently in stock. The customer should be able to purchase several different items at one time.

Exception

The exception should be thrown when an item is being added to the purchase list of items. It should check at that point if there are enough items to purchase. If there is not enough in the inventory, then the exception should be thrown. Handled correctly in main $($program should not crash and customer should be able to continue$).$

CashRegister

Main interacts with this class only $($except to create the initial inventory of items$).$ Main populates the inventory via this class. The customer should see a menu of items that can be purchased. The customer will then start selecting items to purchase one at a time and determine when they are done. Information about the purchase should be displayed. Then the menu of the inventory is displayed again to allow the next customer to make a purchase. Uses a linked list to keep track of the items purchased for the customer. When an item has no more inventory it should be removed from the inventory and not displayed in the menu.

Inventory

Created by the CashRegister and populated via the CashRegister class. Provides methods to support keeping the inventory up to date. When adding an item to the inventory the add method must check to make sure the items do not already exist in the inventory. If already in the inventory, then do not add it$.$

All Electronics classes

This forms an inheritance hierarchy. Base$($super$)$ is abstract and implements the interface Comparing $($see below$).$ The description method just returns a generic message about the item, this is a hardcoded string.

Interface

The one method declared in the interface that the electronics implements is used to check if an item being added is already in the list. This prevents duplicate items being added to the inventory. Note this interface must also be a generic.