I have to have multiple classes for this program. The problem is, I don't fully understand arrays and how they work, so I'm a little lost. I will post my program I have written thus far so you can see what I'm working with, but I don't expect anyone to DO my assignment for me. I just need to know where to start and I'll try to go from there. I think I need to use a double array since I will be working with decimals since it deals with money, and my method call needs to calculate total price for all items entered by the user. Please help:

RUNNING FILE

package inventory2;
import java.util.Scanner;

public class RunApp
{ 
   public static void main(String[] args)
{

        Scanner input = new Scanner( System.in );

        DataCollection theProduct = new DataCollection();

        String Name = "";
        double pNumber = 0.0;
        double Units = 0.0;
        double Price = 0.0;
    while(true)                                       
    {
        System.out.print("Enter Product Name: ");
        Name = input.next();
        theProduct.setName(Name);
        if (Name.equalsIgnoreCase("stop"))        
            {
                return;
            }

        System.out.print("Enter Product Number: ");
        pNumber = input.nextDouble();
        theProduct.setpNumber(pNumber);

        System.out.print("Enter How Many Units in Stock: ");
        Units = input.nextDouble();
        theProduct.setUnits(Units);

        System.out.print("Enter Price Per Unit: ");
        Price = input.nextDouble();
        theProduct.setPrice(Price);

        System.out.print("\n Product Name:     " + theProduct.getName());
        System.out.print("\n Product Number:     " + theProduct.getpNumber());
        System.out.print("\n Amount of Units in Stock:     " + theProduct.getUnits());
        System.out.print("\n Price per Unit:    " + theProduct.getPrice() + "\n\n");
        System.out.printf("\n Total cost for %s in stock: $%.2f\n\n\n", theProduct.getName(), theProduct.calculatePrice());
        }
    }
}

DATA COLLECTION FILE

package inventory2;

    public class DataCollection
{
        String productName;
        double productNumber, unitsInStock, unitPrice, totalPrice;   

    public DataCollection()
    {
    productName = "";
    productNumber = 0.0;
    unitsInStock = 0.0;
    unitPrice = 0.0;
    }

        //setter methods
    public void setName(String name)
    {
    productName = name;
    }

    public void setpNumber(double pNumber)
    {
    productNumber = pNumber;
    }

    public void setUnits(double units)
    {
    unitsInStock = units;
    }

    public void setPrice(double price)
    {
    unitPrice = price;
    }

        //getter methods
    public String getName()
    {
    return productName;
    }

    public double getpNumber()
    {
    return productNumber;
    }

    public double getUnits()
    {
    return unitsInStock;
    }

    public double getPrice()
    {
    return unitPrice;
    }

    public double calculatePrice()
    {
    return (unitsInStock * unitPrice);
    }
}