Wednesday, December 07, 2005 3:22 PMHi, I tried the sample from MSDN
But it did not compile.
The ListBox is loaded thus:
DimUSStates As New ArrayList
USStates.Add(New USState("Washington", "WA"))
USStates.Add(New USState("West Virginia", "WV"))
USStates.Add(New USState("Wisconsin", "WI"))
USStates.Add(New USState("Wyoming", "WY"))
ListBox1.DataSource = USStates
ListBox1.DisplayMember = "LongName"
ListBox1.ValueMember = "ShortName"
But then I run into trouble here:
PrivateSub ListBox1_SelectedValueChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ListBox1.SelectedValueChanged If ListBox1.SelectedIndex <> -1 Then
textBox1.Text = ListBox1.SelectedValue ' Raises InvalidCastException
I get the following message:
An unhandled exception of type 'System.InvalidCastException' occurred in microsoft.visualbasic.dll
Additional information: Det går inte att omvandla typen USState till typen String.
Translating to "Cannot convert the type USState to the type String".
What is wrong here?
Wednesday, December 07, 2005 4:41 PMListBox1.SelectedValue will be an object, while textBox1.Text is expecting text.
I think that sample code is simply missing a .ToString at the end:
textBox1.Text = ListBox1.SelectedValue.ToString
Wednesday, December 07, 2005 10:39 PMThanks Jason, you were quit right.
But I'm still a bit confused, .SelectedValue should not have returned an USState type object, it should have returned an object of the type used in the USState.ShortName property, which is String.
And even if it did return an USState object, the .ToString function should not have returned the correct answer but a concatenation of both the long and short name.
So why does VS tell me I got an USState when I clearly got a String casted as an object?
Wednesday, January 18, 2006 3:25 AM
I get this, but how do you load a ListBox from a collection. Specifically, I wanted to populate a ListBox with the contents of a DataTableCollection....eg DataSource.Tables property..
I can see a List property but that is protected. What is the use of such a property which appears to be spot on the mark, or is it that it isn't implemented and is only intended to be overriden?