Indus

Indus is an e-store, like Amazon. An item in the Indus inventory, like a DVD, has a unique identity number and an associated product description that contains a brief description of the product, such as the title of the DVD, the price (in pennies), and the name of the supplier where more items can be ordered::

Part 1

Implement the Item and Description classes in Scala. Provide companion objects with apply methods for each class.

Part 2

Users should not be trusted to provide unique id numbers for each item. Instead, these should be automatically generated. In Java we might create a private static nextId variable that stores the next available id number. The Item constructor could use this to initialize id, then increment the variable:

this.id = Item.nextId++;

Scala doesn't have static variables. Instead, nextId can be declared in the Item companion object.

Part 3

As in Java, every Scala class inherits useful methods from a cosmic superclass (called AnyRef, more on this later). For example, the inherited toString is automatically called when an object appears in a context where a string is expected. This method can be overridden in the Item and Description classes to create more attractive strings. Warning: you must declare that you are overriding a method:

override def ...

Part 4

Create an application object called Indus containing an inventory field of type ArrayBuffer[Item]. Stock the inventory with the following items:

Print the inventory.