Windows Phone 8中工具包列表选择器的必填字段

Question

我是Windows手机开发的新手。在我的应用程序中，我有一个包含

listpicker

字段的表单，我想把这个字段作为必填字段。有什么方法可以做到吗？

提前致谢！

Answer 1

嗨，请试试这个

<强> 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＃：

  

string param =＆＃34;＆＃34;;

    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);
        }
    }