How to prevent value changed events from firing on form initialization in .NET?

Question

Consider a simple .NET form with a couple of radio buttons and a checkbox.

Each of the radio buttons has a CheckedChanged handler setup that performs some action based on the state of the checkbox.

My problem is, when I initialize on the default radiobutton to be checked (from the designer properties window) the CheckedChanged event is fired for that radio button, but the Checkbox hasn't been initialized yet so I either get a null pointer exception or the wrong value is used in the handler. Either way, I don't want that handler code to be run unless the user picks a radio button after the form has been loaded.

I currently get around this by not initializing the radio button, but I need to set that default eventually and the best place is from the designer. I also can add a boolean field that's not set to true until the form is fully loaded and not process the events if that is false, but it's a dirty hack.

What can I do to prevent that handler from running its code?

Answer 1

To make it feel slightly less dirty, if you initialize the controls in the constructor of the form you might be able to use the forms IsHandleCreated property rather than your own bool to check if it should actually validate or not.
I would think that normally you wouldn't want to validate anything before it's been shown for the first time and handle isn't created until it is.

Code Example:

Private Sub myRadioButton_CheckedChanged(sender As Object, e As EventArgs) Handles myRadioButton.CheckedChanged If myRadioButton.Checked AndAlso myRadioButton.IsHandleCreated Then     'Do Work End If End Sub