Windows Phone 8 中工具包列表选取器的必填字段

Question

我是Windows Phone开发的新手。在我的应用程序中，我有一个包含

列表选择器

字段的表单，我想将此字段作为必填字段。有什么办法吗？？

提前感谢！

Answer 1

嗨，

请尝试这个

XAML

<Grid x:Name="LayoutRoot">
    <toolkit:ListPicker x:Name="Listpickername"
                        Margin="37,42,149,430" 
                        Foreground="Black"
                        ExpansionMode="ExpansionAllowed" 
                        Background="#FFF7EBEB" SelectionChanged="Listpickername_SelectionChanged">
    </toolkit:ListPicker>
    <Button Content="Check" Click="checklistitem" HorizontalAlignment="Left" Margin="143,344,0,0" VerticalAlignment="Top" Width="236"/>
</Grid>

C# ：

字符串参数 = ";

    public PanoramaPage1()
    {
        InitializeComponent();
        Listpickername.Items.Add("Item1");
        Listpickername.Items.Add("Item2");
    }
    private void Listpickername_SelectionChanged(object sender, SelectionChangedEventArgs e)
    {
        if (Listpickername.SelectedItem!=null)
        {
            param = Listpickername.SelectedItem.ToString();
        }
    }
    private void checklistitem(object sender, RoutedEventArgs e)
    {
        if(param==string.Empty)
        {
            MessageBox.Show("Please select item");
        }
        else
        {
            MessageBox.Show("selected item is " + param);
        }
    }