C# Listpicker和返回值

我是这门语言的新手。我读了这本指南 但我仍然有一个问题：

 // Constructor
    public MainPage()
    {
        InitializeComponent();
        List<SampleData> dataSource = new List<SampleData>();
        dataSource.Add(new SampleData() { Day = "Sunday"});
        dataSource.Add(new SampleData() { Day = "Monday"});
        dataSource.Add(new SampleData() { Day = "Tuesday"});
        dataSource.Add(new SampleData() { Day = "Thirsday"});
        dataSource.Add(new SampleData() { Day = "Wednesday"});
        dataSource.Add(new SampleData() { Day = "Friday" });
        dataSource.Add(new SampleData() { Day = "Saturday"});
        this.listPicker.ItemsSource = dataSource;
    }

    public class SampleData
    {
        public string Day { get; set; }
               }

我没有选择日期，但出现无效的强制转换错误，我不知道选择了返回值。

---

你能帮我吗？

你把

SampleData

放到

列表选择器中。如果要使用“
Day
”属性，应使用

private void button1_Click(object sender, RoutedEventArgs e)
    {  
 var sampleData =(SampleData)listPicker.SelectedItem;
 var day = sampleData.Day;
MessageBox.Show(day);    
 }

private void button1_Click(object sender, RoutedEventArgs e)
    {  
 var sampleData =(SampleData)listPicker.SelectedItem;
 var day = sampleData.Day;
MessageBox.Show(day);    
 }