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Value type 'String' cannot be converted to 'Telerik.Wincontrols.RadItem

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ComboBox and ListBox (obsolete as of Q2 2010)
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gdijim
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gdijim asked on 06 Jun 2007, 08:08 AM



Private Sub RadButton2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles RadButton2.Click

'Executes Ping.exe -t With RadComboBox1 as Variable

With Me.RadComboBox1

If Not Me.RadComboBox1.Items.Contains(Me.RadComboBox1.Text) Then

.Items.Add(RadComboBox1.Text)

End If

End With

 

Process.Start("\pingdev.bat", RadComboBox1.Text)


This code works with the VS combobox - I'm trying to figure out what I'm doing wrong -

I get this error -

Value type 'String' cannot be converted to 'Telerik.Wincontrols.RadItem


Can anyone help?

Thanks!
Jim


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Georgi
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answered on 06 Jun 2007, 08:56 AM
Hello gdijim,

The reason you get this error is because the RadComboBox.Items collection contains objects of type RadComboBoxItem instead strings, so its Contains method expects RadItem object as parameter (RadComboBoxItem is RadItem descendant ). In your case, you could use the FindItemExact method:

If Me.RadComboBox1.FindItemExact(Me.RadComboBox1.Text) Is Nothing Then

I hope this helps.
 

Greetings,

Georgi
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gdijim
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answered on 06 Jun 2007, 09:43 AM
Almost done at work for the day - Will try that out when I get home.

You guys are awsome!  What a response time ;)

Jim
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gdijim
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answered on 07 Jun 2007, 05:28 AM
Okay, I've got it to where I can check the Combobox to see if the text already resides there:

If Me.RadComboBox1.FindItemExact(Me.RadComboBox1.Text) Is Nothing Then



But how do I add strings to the combobox?


.Items.Add(radComboBox1.Text)

doesn't work, because it's expecting an object, not a string, as you say.  Which option should I use to add a string? 

Sorry, still trying to get a handle on Object oriented programming.

Thanks!
Jim


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Georgi
Telerik team
answered on 07 Jun 2007, 03:45 PM
Hello gdijim,

Again, you're trying to use a method from the Items collection with a string parameter. Items collection is a collection of objects of type RadItem, and in the case of  the combobox - objects of type RadComboBoxItem. You should always use the RadComboBoxItem type when you work with Items collection. 

To add a new item in the combobox you should first create the item and then add it to Items collection:

Dim item1 as RadComboBoxItem = New RadComboBoxItem(Me.RadComboBox1.Text)

I'll suggest reviewing our combobox examples in the examples that come with installation. Each example comes with its C#/VB code (in the tabs located above the example) and you can see how we do things there.

Let me know if this clears things up.

 
Best wishes,
Georgi
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gdijim
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answered on 07 Jun 2007, 08:15 PM
That did it - and you explained a a very important piece of programming I've been missing - A lot of things just clicked.

You guys are really great - thanks for the help,
Jim
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ComboBox and ListBox (obsolete as of Q2 2010)
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