object reference error

I have this bit of code

Code:

---

Private Sub SpellChkMenuItem_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles SpellChkMenuItem.Click
        Dim activeRichTextBox = TryCast(Me.ActiveControl, RichTextBox)
        'clsFS.CheckSpelling(activeRichTextBox)
        'clsFS.SpellAndGrammarCheck(activeRichTextBox)
        If Len(activeRichTextBox.Text) > 0 Then
            SpellChecker.Text = activeRichTextBox.Text
            SpellChecker.SpellCheck()
        Else
            MsgBox("Text box is empty")
            End If
    End Sub

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When I am in the rtb and click on spell check button it tells me the error

"Object reference not set to an instance of an object."

On this line

SpellChecker.Text = activeRichTextBox.Text

But it is suppose to be getting the focused rtb correct? So why is it not referenced

Try the following

Code:

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    Private Sub demo()
        Dim activeRichTextBox As New RichTextBox
        If TypeOf Me.ActiveControl Is RichTextBox Then
            activeRichTextBox = DirectCast(Me.ActiveControl, RichTextBox)
            If activeRichTextBox.Text.Length > 0 Then
                ' assumes SpellChecker exists already and has been properly created
                SpellChecker.Text = activeRichTextBox.Text
                SpellChecker.SpellCheck()
            Else
                MsgBox("Text box is empty")
            End If
        Else
            Console.Write("Nope")
        End If
    End Sub

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Doesn't the menuitem become the activecontrol when you click on it? And obviously a menuitem cannot be cast to a richtextbox, so TryCast(me.activecontrol, richtextbox) returns Nothing therefore you get a null reference exception when you try to treat Nothing as a richtextbox.

So would it be better if I had a right click menu on the RTB?

Possibly not... as then the menu would become the active control.
the way I'd deal with it (and admittedly it is far less than ideal) is to create a form level object of type RTB... then as an RTB gets focus (I'm assuming you have more than one) ... set the form-level object equal to the RTB that just got focus... then use the form-level object in your code above.

-tg

Quote:

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Originally Posted by stanav

Doesn't the menuitem become the activecontrol when you click on it? And obviously a menuitem cannot be cast to a richtextbox, so TryCast(me.activecontrol, richtextbox) returns Nothing therefore you get a null reference exception when you try to treat Nothing as a richtextbox.

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Yes the menu item becomes the active control but the ContextMenu SourceControl property indicates which control invoked the menu item as shown below.

Code:

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Private Sub DemoToolStripMenuItem_Click( _
    ByVal sender As System.Object, _
    ByVal e As System.EventArgs) _
    Handles DemoToolStripMenuItem.Click

    If ContextMenuStrip1.SourceControl IsNot Nothing Then
        If TypeOf ContextMenuStrip1.SourceControl Is RichTextBox Then
            Dim activeRichTextBox As New RichTextBox
            activeRichTextBox = DirectCast(ContextMenuStrip1.SourceControl, RichTextBox)
            activeRichTextBox.AppendText("Hello")
        End If
    End If

End Sub

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Thanks techgnome, I will give that a shot

And thank Kevin, I will look over that as well.