asp.net listbox problem

Question

1.50/5 (2 votes)

See more:

In my application having Asp.net Listbox Control.
and this is content page.suppose i am using form it will work fine.but using content page the list box is not work.
now i used in my code:
dim getitem as string=listbox1.selecteditem.tostring().
but i have got error as Object reference not set to an instance of an object.
how can i solve this problem...

Posted 17-Feb-12 0:49am

Masila.R

Updated 19-Feb-12 18:21pm

v2

Add a Solution

Comments

Varun Sareen 17-Feb-12 7:03am

Please post some code. The listbox is not being filled i think

Ed Nutting 17-Feb-12 7:30am

Agreed - impossible to answer without code as it could be Varun's answer or it could be the user didn't select anything or it's the infamous SelectedItem isn't reliable where as SelectedIndex is or it's because he didn't give a value to the selected item or..or...or...

kishore sharma 20-Feb-12 0:41am

Hi, IT Depends how you are bindint listbox, its no where related to content page& master page.You are using property as selecteditem (it will give selected text & selected value) so you cant take as string.
you can take as dim lstItem as listitem=listbox1.selecteditem.
(check once where you are bindng are you binding withour if not page.ispostback)

please post clear.

thanks

Masila.R 25-Feb-12 0:28am

thanks.i found my mistake with ur help..
s i have bind without if not page.ispostback..
now it s working.
thanks again...

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Sergey Alexandrovich Kryukov · Answer 1 · 2012-02-20T12:48:00

Let's assume listbox1 is not null. So, the problem happens because none of the list box items is selected; in this case listbox1.SelectedItem is null; you are trying to dereference null reference by using ToString, which gives you this exception.

Please always run your code under debugger before asking questions like this one. If you did, you would see the problem immediately. Generally, always use the debugger every time you have a slightest concern about your run-time behavior.

[EDIT]

Please see my past answer where I complied several past answers on related problems, with source code samples applicable to ComboBox and ListBox:
combobox.selectedvalue shows {} in winform[^].

—SA