Complicated Array Problem

[Alice Bickerstaff]

Hi,

I have created a class ShoppingCart that constructs a new arry from a class called Item. The Item array consists of 10 elements. Each Item element holds an Item object that contains the instance variables

    private String name;
    private double price;
    private int quantity;
    private int barcode;

When the array is first created the first index of the array becomes non-null and the remaining nine indices are still null objects. As a new Item object is added to the Item array I need to compare the new objects barcode data with the existing array elements' barcode data. If the data are the same then I need to only update the quantity of the item and not store this object information again in a separate array. Only the quantity data needs to be updated.

Here is the code that I have so far for this particular algorithm. Although it doesn't create compile-time or run-time errors, it does not function as it should

 public void addToCart(String itemName, double price, int quantity, int barcode)
    {
 

     if (itemCount == cart.length)
   increaseSize();
 

      if (cart[barcode] == null)
{
    cart[itemCount] = new Item (itemName, price, quantity, barcode);
    totalPrice += (price * quantity);
    itemCount++;
}
 
else
{

   for (int i = 0; i <= cart[barcode]; i++)
   {
    

               if (cart[barcode].equals(cart[i]))
       {
 
         quantity += cart[i].getQuantity();
         cart[i] = new Item (itemName, price, quantity, barcode);
         totalPrice += (price*quantity);
       }
    
    }
 }
  
      
        
 
    } 

Thanks for any help that is offered

[Michael Dunn]

Just a thought - it might be easier if you changed your array to a Hashtable,
using the barcode as the key, then simply check containsKey()

[Alice Bickerstaff]

Thanks Michael,

I'll give that a try. Any ideas on how to make that happen using an array?

[Michael Dunn]

class Testing
{
  Item[] cart = new Item[10];
  int itemCount = 0;
  double totalPrice = 0.0;
  public Testing()
  {
    addToCart("Chips",1.25,5,123);
    addToCart("Coke",2.25,10,222);
    printCart();
    addToCart("Coke",2.25,20,222);
    printCart();
  }
  public void addToCart(String itemName, double price, int quantity, int barcode)
  {
    if (itemCount == cart.length) increaseSize();
    for (int x = 0; x < itemCount; x++)
    {
      if(barcode == cart[x].barcode)
      {
        cart[x].quantity += quantity;
        totalPrice += (price*quantity);
        return;
      }
    }
    cart[itemCount] = new Item (itemName, price, quantity, barcode);
    totalPrice += (price * quantity);
    itemCount++;
  }
  public void printCart()
  {
    for(int x = 0; x < itemCount; x++)
    {
      System.out.println(cart[x].name+" "+cart[x].quantity);
    }
    System.out.println("===");
  }
  public void increaseSize()
  {
    //do something here;
  }
  public static void main(String[] args){new Testing();}
}
class Item
{
  String name;
  double price;
  int quantity;
  int barcode;
  public Item(String n,double p,int q,int b)
  {
    name = n;price = p;quantity = q;barcode = b;
  }
}