if listbox selected item is null or empty

[dwyane123]

Hi all, need help here,

i need to make a if condition where non of the item in he listbox is selected

i tried

if lstlistbox.selectedItem.toString = ""
'stop

else

' continue

end if
however, it returns an error "NullReferenceException"
so how is it possible for me to make the if condition where the non of the item in the listbox is selected.

Thanks alot

 

[Robert_Zenz]

Hello.

ToString() Is a function like every other one, of course it's returning this exception...go with this instead:

If listBox.SelectedItem IsNot Nothing AndAlso listBox.SelectedItem.ToString() <> "" Then
End If

AndAlso is a short circuit Operator, which means that if the first condition fails, he doesn't even bother to look at the other conditions (this is why ToStirng isn't failing in this case).

Bobby

 

[dwyane123]

Hey bro the If listBox.SelectedItem IsNot Nothing works well but not listBox.SelectedItem.ToString() <> "". Using the whole code you give shows the error like what i receive just now. Therefore i think i will just use " If listBox.SelectedItem IsNot Nothing " as it work well

Anw. Thanks alot for you help

Hello.

ToString() Is a function like every other one, of course it's returning this exception...go with this instead:

If listBox.SelectedItem IsNot Nothing AndAlso listBox.SelectedItem.ToString() <> "" Then
End If

AndAlso is a short circuit Operator, which means that if the first condition fails, he doesn't even bother to look at the other conditions (this is why ToStirng isn't failing in this case).

Bobby

 

[Solitaire]

Try this:

If listBox.SelectedIndex = -1

indicates that nothing was selected.

 

[jmcilhinney]

Try this:

If listBox.SelectedIndex = -1

indicates that nothing was selected.

Absolutely. Why would you have to check for an empty string? Why would you be putting empty strings into your ListBox in the first place?