This program is a command-line based utility for creating shoppers and products (presumably for a store), handling shoppers purchasing products, and displaying information about shoppers and products. It is designed in order to give you an opportunity to:

Utilize all you have learned so far about writing program statements.
Introduce you to programs consisting of multiple classes
Introduce you to the idea of understanding and adding to code written by others
Give you practice in writing and using methods in your own code

The whole program will consist of four classes:

DriverClass: This is the primary class for this program, because it holds the main method. Much of this code uses techniques we have not covered yet.
MethodHolder: It contains the primary methods used in DriverClass. The methods are static, so you do not create an actual object in order to use them.
Shopper: This class represents the idea of a "shopper", so a particular Shopper object represents a specific shopper at the store. A shopper has an ID, a name, a balance, and a limit on how many products s/he can purchase. Shopper ID numbers start at 100.
Product: This class represents the idea of a "product" one could purchase, so a particular Product object represents a specific product at the store. A product has an ID, a name, a department, a description, a price, and an "initial count" (i.e., how many of the product the store has in stock, at the start of the program). Product ID numbers start at 100.

The ONLY .java file in which you will have to write code is MethodHolder.java - though you need to at least understand how the Shopper and Product classes work. (Hint: If you find yourself thinking you need to change/add code in any place other than where I've told you to do so, that's a good sign you need to let me or someone know what obstacles you are running up against.) Notice the following two lines near the start of the code:

    private static int nextShopperID = 100;
    private static int nextProductID = 100;

These variables hold the ID numbers to be given to the next shopper created and the next product created, respectively. Because these variables have been declared outside of the methods, they will be available to code inside the methods. Because both shopper IDs and product IDs start at 100, each of the variables is initialized to that. Remember this for later, when it appears in one of the code requirements.

You will write code for the following four methods:

protected static Shopper generateShopper(): Write code to prompt user for input, accept said input, and assign it to the following three variables, respectively:
- name
- balance
- productLimit
In addition, you will need to make a small change to the following line of code:
return new Shopper(-1, name, balance, productLimit);
Specifically, you must replace the -1 with something that will evaluate to the appropriate integer value for the new shopper's ID number -- as well as ensuring that everything is set up for the ID of the next shopper created.
protected static Product generateProduct(): Same as the previous, for the following five variables, respectively:
- name
- department
- description
- price
- initialCount
In addition, you will need to make a small change to the following line of code:
return new Product(-1, name, department, description, price, initialCount);
Specifically, you must replace the -1 with something that will evaluate to the appropriate integer value for the new product's ID number -- as well as ensuring that everything is set up for the ID of the next product created.
protected static void printShopperInfo(Shopper s): For the Shopper object referred to by s, print the following pieces of information:
1. Name
2. Products Bought
3. Can Still Buy
4. Spent So Far
5. Balance Remaining
6. Products shopper has purchased
In order to do this part, you will need to know how to call an instance method, with respect to a particular object reference; in this context, that is simply the variable s, for all intents and purposes. In addition, you will need to study the Shopper class to see what methods you should be calling. Pay attention to such details as the method's name and the type of data it gives you. Also, some of the pieces of information you are seeking will not be directly provided by a method -- in which case, you will need to retrieve other information to calculate the result.

The Shopper class already has an instance method that will print the shopper's products for you, though it does not go inside a println like the others. Look for methods in Shopper.java that provide the pieces of information you need. Your job is to figure out the pattern.
protected static void printProductInfo(Product p): For the Product object referred to by p, print the following pieces of information:
1. Name
2. Department
3. Description
4. Price
5. Number Bought
6. Number Remaining
7. Shoppers who bought this product
In order to do this part, you will need to know how to call an instance method, with respect to a particular object reference; in this context, that is simply the variable p, for all intents and purposes. In addition, you will need to study the Product class to see what methods you should be calling. Pay attention to such details as the method's name and the type of data it gives you. Also, some of the pieces of information you are seeking will not be directly provided by a method -- in which case, you will need to retrieve other information to calculate the result.

The Product class already has an instance method that will print the shoppers for you, though it does not go inside a println like the others. The first piece of information, the title, is already done for you. Look for methods in Product.java that provide the pieces of information you need. Your job is to figure out the pattern.

Click here for a live demonstration of a very similar program in action. The substantive material is different but the overall pattern of interaction and behavior is very close to this one.