I have an control that i开发者_如何学Gonherits from another control (TxTextControl). I have a SelectedText property that basicaly wraps the base SelectedText property, which is apparently needed because my control is implementing an interface with that property. The code is this:
public string SelectedText
{
get
{
return base.Selection.Text; // Error here (#1042)
}
set
{
if (base.Selection == null)
{
base.Selection = new TXTextControl.Selection(0, 0);
}
base.Selection.Text = value;
}
}
When I drop this control on a form, no problems. It compiles and runs. Everything looks great. However, when I save, close then reopen the form, the form designer shows this error:
Object reference not set to an instance of an object.
1. Hide Call Stackat Test.FormattedTextBox2.get_SelectedText() in C:\Projects\Test\FormattedTextBox2.cs:line 1042
Anyone know what is going on? I'm about to pull out my last hair...
UPDATE:
darkassisin93's answer wasn't exactly correct, but that was because my posted code wasn't exactly accurate. I needed to test if base.Selection was null before attempting to access a property of that object. In any case, that answer got me headed in the right direction. Here is the actual solution:public string SelectedText
{
get
{
string selected = string.Empty;
if (base.Selection != null)
{
selected = base.Selection.Text;
}
return selected;
}
set
{
if (base.Selection == null)
{
base.Selection = new TXTextControl.Selection(0, 0);
// Have to check here again..this apparently still
// results in a null in some cases.
if (base.Selection == null) return;
}
base.Selection.Text = value;
}
}
Try replacing
return base.SelectedText;
with
return base.SelectedText ?? string.Empty;
It's most likely because the base class's SelectedText
property is set to null.
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