Question

我有一个带有列表框的wpf应用程序。我尝试访问listbox.selectedValue但它是null，我不明白。它甚至有一个默认选择，为什么它一直保持为空？非常感谢任何线索

private void save_Click_1(object sender, RoutedEventArgs e)
{
    string name = foodName.Text;
    string type = preferenceType.SelectedValue.ToString();
    Preference newPreference = new Preference(name, type);
    string temp = name + ";" + type;
    newPreference.save(temp, newPreference.path);
    MessageBox.Show($"{name} {type} saved");
}

和xaml：

<TextBox x:Name="foodName" TextWrapping="Wrap" Text="Food name" GotFocus="foodName_GotFocus" HorizontalScrollBarVisibility="Auto" Grid.ColumnSpan="3" Margin="1.4,50,10.2,280" Grid.Column="1"/>
<ListBox x:Name="preferenceType" Grid.ColumnSpan="3" Margin="1.4,81,10.2,246" Grid.Column="1">
    <ListBoxItem Selected="ListBoxItem_Selected">allergy</ListBoxItem>
    <ListBoxItem Selected="ListBoxItem_Selected">hate</ListBoxItem>
    <ListBoxItem Selected="ListBoxItem_Selected">dislike</ListBoxItem>
</ListBox>
<Button x:Name="savePreference" Content="Save" HorizontalAlignment="Left" Margin="1.4,115,0,0" VerticalAlignment="Top" Width="78" Click="save_Click_1" Grid.ColumnSpan="3" Grid.Column="1" Height="19"/>

Answer 1

试试这段代码：

        ListBoxItem testitem = preferenceType.SelectedValue as ListBoxItem;
        string name = foodName.Text;
        string type = testitem.Content.ToString();
        Preference newPreference = new Preference(name, type);
        string temp = name + ";" + type;
        newPreference.save(temp, newPreference.path);
        MessageBox.Show(name + type + "saved");

C＃listBox selectedValue保持为null

1 个答案: