array in session

[Malhar Barai]

hi all
i m making a Shopping Cart & i need to store array of values in session. it does get stored, but at a time i only get to see one value only, even after i run the "FOR" loop.
my doGet is as below

  
//getting the ITEM ID from Static Page
String[] item_id = {req.getParameter("item_id")};
int qty_def=1;

//if session is new put the values in session
if(session.isNew())
{
session.putValue("item_id",item_id);
session.putValue("qty",new String[] {Integer.toString(qty_def)});
}
//if session is old
else
{
//retrieving ITEM IDs from session
        String[] chk_item = (String[])session.getValue("item_id");
int flag=0;

        for(int c=0; c<chk_item.length;c++)
{
//if that ID already exists in session
                if(chk_item[c].equals(item_id[c]))
{
String[] qty_s = (String[])session.getValue("qty");
int qty = Integer.parseInt(qty_s[c]);
qty++;

                        //update quantity for that ITEM
                        session.putValue("qty",new String[] { Integer.toString(qty) });
         }
         else
         {
       //THIS IS WHERE I FACE THE PROB
                       //if the ITEM doesnot exist add it to the session but it doesnt add but overwrites on the previous ITEM. 
int qty = 1;
        String[] qty_a = {Integer.toString(qty)};
        session.putValue("item_id",item_id);
        session.putValue("qty", qty_a);

  }
}
}

in doPost I retrieve the values from session .

  
//getting ITEM IDs
String[] item_id = (String[])session.getValue("item_id");
//getting ITEM Quantity
String[] qty = (String[])session.getValue("qty");
out.println(session+"<br>");
out.println(item_id.length+"<br>");

for(int i = 0; i<item_id.length; i++)
{
out.println(item_id[i]+"\t"+qty[i]+"<br>");
}

need more info...??
tia
MB..
[ December 14, 2002: Message edited by: malhar barai ]

[William Brogden]

Could you restate exactly what your requirements are in a more general way? I can't really tell what you are trying to do.
Bill

[Sandeep Jain]

Hi ,
I feel u will get only 1 item back from the existing program as u are not appending the item item_id
Every time the request come to the server a item_id is created with 1 element.
So what u have to do is , first get the array from session add the new element to it and then put the array back in the session .

[Malhar Barai]

Originally posted by William Brogden:
Could you restate exactly what your requirements are in a more general way? I can't really tell what you are trying to do.
Bill

hi bill
the problem is exactly as understood by sandeep. I am able to get only one item in the session.
MB
thnx anyway

[Malhar Barai]

Originally posted by Sandeep Jain:
Hi ,
I feel u will get only 1 item back from the existing program as u are not appending the item item_id
Every time the request come to the server a item_id is created with 1 element.
So what u have to do is , first get the array from session add the new element to it and then put the array back in the session .

hi Sandeep
You are bang on target. but do i achieve this. what I tried is
String[] item_id = (String[])session.getValue("item_id");
item_id[item_id.length+1] = item_value;//new item being stored
session.putValue("item_id",item_id);
but this isn't wrking fine with me, any changes...??
thnx anyway
MB..still

[William Brogden]

hi bill
the problem is exactly as understood by sandeep. I am able to get only one item in the session.

That is NOT what I said. I asked what you are trying to do! A very different question.
If you want to keep adding items to the session, this is not the way to go about it. You are trying to use a String array - but arrays can not be expanded. Perhaps you want to use one of the collection classes?
Bill

[Kyle Brown]

I agree with Bill. Use a Vector and your problem should go away -- Also -- rather than storing things as you are, consider creating an Item class that contains price, quantity and description fields. Then store the Items in a Vector held in the HttpSession.
Kyle

[Malhar Barai]

Originally posted by Kyle Brown:
Use a Vector and your problem should go away -- Also -- rather than storing things as you are, consider creating an Item class that contains price, quantity and description fields. Then store the Items in a Vector held in the HttpSession.
Kyle

hi kyle
I think that would solve my problem. About the Item class...can you shed some more light on that. Do you mean to say I should create an Item class with price,quantity & description & access it by Item.price & so on...??? or have I misunderstood you..??
thnx anyway
MB

[Kyle Brown]

Yes, that is exactly what I am saying. Your code for adding a new item would look like:
Item anItem = new Item(price,quantity,desc);
Vector items = (Vector) session.getAttribute("items");
items.add(anItem);
session.putAttribute("items", items);
To get it back;
Vector items = (Vector) session.getAttribute("items");
Enumeration enum = items.elements();
while (enum.hasMoreElements()) {
Item item = (Item) enum.nextElement();
double price = item.price;
String desc = item.desc;
int qty = item.qty;
// now print them out or whatever
}
Item would just have the attributes described above, a constructor, and maybe some getters and setters. This is called OBJECT-ORIENTED PROGRAMMING and it's what you're supposed to do in Java
Kyle

[Malhar Barai]

thnx a ton kyle & all others who helped me out.
MB