Combo box selection item returning an error

Question

I created a combo item in xaml as follows:

 ComboBox x:Name="CmbBoxStart" HorizontalAlignment="Left" Height="108" Margin="10,191,0,0" VerticalAlignment="Top" Width="174" ItemsSource="{Binding}" SelectionChanged="CmbBoxStart_SelectionChanged" FontSize="25" IsDropDownOpen="False" BorderThickness="10" Background="{StaticResource ComboBoxBackgroundThemeBrush}" Foreground="{ThemeResource ComboBoxForegroundThemeBrush}" IsSynchronizedWithCurrentItem="False"> <x:String>0</x:String> <x:String>1</x:String> <x:String>2</x:String> <x:String>3</x:String> <x:String>4</x:String> <x:String>5</x:String> <x:String>6</x:String> <x:String>7</x:String> <x:String>8</x:String> <x:String>9</x:String> </ComboBox>

When I get the chosen value in c# I get the "Null Reference exception error"

Here is my C# code.

Any ideas If I need to bound this? I thing the error has to do with the index of the value.

 private void CmbBoxStart_SelectionChanged(object sender,SelectionChangedEventArgs e) { if (CmbBoxStart.SelectedIndex != null) { string StrStartString = CmbBoxStart.SelectionBoxItem.ToString(); IntStartNumber = Convert.ToInt16(StrStartString); //CmbBoxStart.GetValue(Item) } }

Muhammad Ali · Accepted Answer · 2015-02-17 02:59:56Z

2

Use SelectedItem instead in place of SelectedIndex

answered Feb 17, 2015 at 2:59

Muhammad Ali

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Comments

The One · Accepted Answer · 2015-02-17 03:07:51Z

This is wrong, int will never be null

 if (CmbBoxStart.SelectedIndex != null)

You must validate SelectedItem !=null

And it seems that SelectionBoxItem is used by the Combobox's ControlTemplate, perhaps you should use just Combobox.SelectedItem property.

string StrStartString = CmbBoxStart.SelectedItem.ToString();

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