Checkbox use giving error??

[RaygunWizzle]

Ok this has been driving me crazy trying to debug this so I am just going to ask for help. I am trying to figure out how to use a checkbox in my add on. Here is all the pertinent code:

private CheckBox checkBox;

(under loadxaml)
checkBox = LogicalTreeHelper.FindLogicalNode(pageContent, "checkbox") as CheckBox;
if (checkBox != null)
checkBox.Checked += CheckBox_Checked;
checkBox.Unchecked += CheckBox_Unchecked;

private void CheckBox_Checked(object sender, RoutedEventArgs e)
{
CheckBox checkBox = sender as CheckBox;
if (checkBox != null)
{
outputBox6.Text = "checked";
}
}
private void CheckBox_Unchecked(object sender, RoutedEventArgs e)
{
CheckBox checkBox = sender as CheckBox;

if (checkBox != null)
{
outputBox6.Text = "unchecked";
}
}

in the XAML file I have
<CheckBox x:Name="checkBox" Content="Check Box" IsChecked="False" IsThreeState="False" VerticalAlignment="Top" Margin="36,61,52,0" Grid.Row="1" />

It will compile fine but whenever I try to open the add on I get "Unhandled exception: object reference not set to an instance of an object"

If comment out this section:
//if (checkBox != null)
// checkBox.Checked += CheckBox_Checked;
// checkBox.Unchecked += CheckBox_Unchecked;

then it loads fine. Can see the checkbox, can check and uncheck it but obviously nothing happens.

What am I getting wrong??
-R

[NinjaTrader_Jesse]

Hello RaygunWizzle,

If you are getting an object reference not set error that would indicate that some portion of your code is having a problem. That error means something was null. Its possible that its this part of your code:

if (checkBox != null)
checkBox.Checked += CheckBox_Checked;
checkBox.Unchecked += CheckBox_Unchecked;​​

The if statement is only checking that the first line of code is not null, the second line is not include in that if statement because there are no curly braces around it, you can try this instead:

if (checkBox != null)
{
checkBox.Checked += CheckBox_Checked;
checkBox.Unchecked += CheckBox_Unchecked;​
}

If that makes the error go away that means the variable checkBox was null and is why the events are not working.

[RaygunWizzle]

Ah, that did the trick. It will compile and load now. But checking and unchecking the box still does nothing. Here is my XAML code for the box:

<CheckBox x:Name="checkBox" Content="Check Box" IsChecked="False" IsThreeState="False" VerticalAlignment="Top" Margin="36,61,52,0" Grid.Row="1" />

and here is the code behind

private void CheckBox_Checked(object sender, RoutedEventArgs e)
{
CheckBox checkBox = sender as CheckBox;
if (checkBox != null)
{
outputBox6.Text = "checked";
}
}
private void CheckBox_Unchecked(object sender, RoutedEventArgs e)
{
CheckBox checkBox = sender as CheckBox;

if (checkBox != null)
{
outputBox6.Text = "unchecked";
}
}
What am I getting wrong? I am assuming its loading now because it is returning Null on the checkbox. But its there in the xaml, and I have it located in the XAML loading code.

[NinjaTrader_Jesse]

Hello RaygunWizzle,

That means the control is null or not being found, the error object reference not set means you tried to use something that was null. If correcting the if statement resolves the error that means the control is null and you are not subscribing to any events because no checkbox was found. It looks like you did not use the correct case for the name when trying to find the control, you need to make sure the controls name matches what you are searching for in the .cs code.

[RaygunWizzle]

Oh SOB I found it.. I forgot to capitalize the B here: checkBox = LogicalTreeHelper.FindLogicalNode(pageContent, "checkbox") as CheckBox;
Thanks!