How to add a VO in vector ,Using Vectors and VO

Question

Actully I have to add a Patch in a working live application it is somthing like this:
it having an VO as
ProductVO product_vo=new ProductVO();
this Product VO having all produt i.e. item code here entries.
Vector vectMasterProductName=new Vector();
String product=null;
double sumTotal = 0;
vectMasterProductName=order_dao.getMasterProductNames();// This vectot contains all the products inthe database
now the old code was :
for (Iterator iterator = vectProduct_vo.iterator(); iterator.hasNext();){
     product_vo=(ProductVO)iterator.next();
     sumTotal=sumTotal+product_vo.getLineTotal();
     product = product_vo.getItemCode();
     }//end for
     //System.out.println("Sumtotal:"+sumTotal);
but this was not handling the case when product_vo is populated with the same itemCode more then one time, now we have to add all the quantities together for the same tpe of peoduct.
when I do this as following:
int count=0;double itemNumber = 0;
     for (int i=0;i<vectProduct_vo.size();i++){
          product_vo=(ProductVO)vectProduct_vo.elementAt(i);
if(vectProduct_vo != null){ 
     itemNumber =product_vo.getQuantity();
     sumTotal=sumTotal+product_vo.getLineTotal();
for(int j=i+1;j<vectProduct_vo.size();j++){
     product_vo1=(ProductVO)vectProduct_vo.elementAt(j);
if(product_vo != null && product_vo.getItemCode().equals(product_vo1.getItemCode())){
     itemNumber=itemNumber+product_vo1.getQuantity();
     vectProduct_vo.set(j,null);
vectProduct_vo.removeElement(null);
System.out.println("Itemcode and Quanity "+product_vo.getItemCode()+": " + itemNumber );
count++;
     order_dao.insertProducts(orderID,vectProduct_vo);
It is working fine for the first item in the vector but after that the vector having no values i.e. I am getting nll pointer exception.I need all the values in the vector but in the same manner as I discussed before that same type of item marg together with the quantity.
Please guide me for the same.
Many thanks It is very very urgent now.

Answer 1

yes you are corrct that it is an old approach but my roject required it.
the vector is properly getting values but when I am using the vector.removeElementAt(j) whole vetor is gettiing null value .. after this I am getting null pointer exception. actully this poduct_VO is populaed through XML comming from other system.
ProductVO extends BaseVO{
     private String itemCode;//same as ProductName
     private double quantity;
     private double itemUnitPrice;
     private String itemDescription;
     private double lineTotal;
     private String itemPremiumDiscount;
     private double itemPremiumDiscountAmount;
     private String productIndicator;
and some getter setter methods.
and the code is same as i discussed first.
what I was trying to change the code for multiple values as
for (int i=0;i<vectProduct_vo.size();i++)
product_vo=(ProductVO)vectProduct_vo.elementAt(i);
if(vectProduct_vo != null)
itemNumber =product_vo.getQuantity();
sumTotal=sumTotal+product_vo.getLineTotal();
for(int j=i+1;j<vectProduct_vo.size();j++){
product_vo1=(ProductVO)vectProduct_vo.elementAt(j);
if(product_vo != null && product_vo.getItemCode().equals(product_vo1.getItemCode()))
{                                             itemNumber=itemNumber+product_vo1.getQuantity();
vectProduct_vo.set(j,null);
vectProduct_vo.removeElement(null);
System.out.println("Itemcode and Quanity "+product_vo.getItemCode()+": " + itemNumber );
count++;
and if I am using removeElementAt(j) the outpou is totally diffrent.
The above code is working fine while i am working in a local environment but fales in the project.
Vector is not populted after one element population.
please help me out, I m not getting the exact way.
     order_dao.insertProducts(orderID,vectProduct_vo);