vbdotnetrookie
New member
- Joined
- Apr 4, 2007
- Messages
- 2
- Programming Experience
- Beginner
Hi, i have gotten the school assignment to create a simple shopping cart system in vb.net, using arraylists. I started out, but being a vb.net rookie i soon stumbled into a problem, which i haven't been able to solve yet, so i turn to you peeps, more experienced vb.net programmers, for some help in solving this.
The following code makes a list of items the user can pick, they can select it, then click the button to add it to their shopping cart (aka winkelwagen in my code)
all looked well till i tried to add an item to my shopping cart, and got the following error: Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.
it's a common error in vb.net i read everywhere, but none the less, i can't seem to figure out what's wrong, any help would be greatly appreciated
as for the code, here it is:
The following code makes a list of items the user can pick, they can select it, then click the button to add it to their shopping cart (aka winkelwagen in my code)
all looked well till i tried to add an item to my shopping cart, and got the following error: Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.
it's a common error in vb.net i read everywhere, but none the less, i can't seem to figure out what's wrong, any help would be greatly appreciated
as for the code, here it is:
VB.NET:
<%@ Page Language="VB" Debug="true" %>
<script runat="server">
Dim lijst, winkelwagen As Arraylist
sub Page_Load(sender As Object, e As System.EventArgs)
if not ispostback then
lijst = new Arraylist
winkelwagen = new arraylist
lijst.add("Chips")
lijst.add("Choco")
lijst.add("Toiletpapier")
lijst.add("Vuilniszakken")
lijst.add("Aardbeien")
rb.DataSource = lijst
rb.DataBind()
end if
rb2.DataSource = winkelwagen
rb2.DataBind()
end sub
sub toevoegen(sender As Object, e As System.EventArgs)
winkelwagen.add(rb.SelectedItem.tostring)
end sub
</script>
<html>
<head>
</head>
<body>
<form runat="server">
<asp:RadioButtonList id="rb" runat="server"></asp:RadioButtonList>
<br />
<asp:Button id="VoegToe" onclick="toevoegen" runat="server" Text="Voeg toe"></asp:Button>
<br />
<asp:RadioButtonList id="rb2" runat="server"></asp:RadioButtonList>
<br />
</form>
</body>
</html>
