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我创建的窗口电话高音例子,得到了NullReferenceException
XML解析错误
我认为这可能是语法上表达的右侧不正确却说不出什么,为什么..
任何人都有一个想法,为什么这导致错误?
.xaml.cs:
public partial class MainPage : PhoneApplicationPage
{
// Constructor
public MainPage()
{
string url = "http://api.twitter.com/1/statuses/user_timeline.xml?screen_name=noradio";
WebClient twitter = new WebClient();
twitter.DownloadStringCompleted += new DownloadStringCompletedEventHandler(twitter_DownloadStringCompleted);
twitter.DownloadStringAsync(new Uri(url));
}
void twitter_DownloadStringCompleted(object sender, DownloadStringCompletedEventArgs e)
{
if (e.Error != null)
return;
XElement xmlTweets = XElement.Parse(e.Result);
listBox1.ItemsSource = from tweet in xmlTweets.Descendants("Status")
select new TweeterItem
{
ImageSource = tweet.Element("user").Element("profile_image_url").Value,
Message = tweet.Element("text").Value,
UserName = tweet.Element("user").Element("screen_name").Value,
};
}
的.xaml:
<ListBox Height="521" HorizontalAlignment="Left" Margin="0,131,0,0" Name="listBox1" VerticalAlignment="Top" Width="476">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal" Height="132">
<Image Source="{Binding ImageSource}" Height="73" Width="73" VerticalAlignment="Top" Margin="0,10,8,0"/>
<StackPanel Width="370">
<TextBlock Text="{Binding UserName}" Foreground="#FFC8AB14" FontSize="28" />
<TextBlock Text="{Binding Message}" TextWrapping="Wrap" FontSize="24" />
</StackPanel>
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
你可以包含堆栈跟踪的例外发生在你的文章?我的赌注是,在你的虚线属性链中有一个空对象。 – 2012-04-03 09:57:49
你说的没错,这里是异常详细信息: System.NullReferenceException了未处理 消息=的NullReferenceException 堆栈跟踪: 在XmlApp.MainPage.twitter_DownloadStringCompleted(对象发件人,DownloadStringCompletedEventArgs E) 在System.Net.WebClient.OnDownloadStringCompleted( DownloadStringCompletedEventArgs e) at System.Net.WebClient.DownloadStringOperationCompleted(Object arg) at – JoeLA 2012-04-03 14:52:18
我得到了这个更具描述性的错误信息。你认为有些参考文献缺失? data.System.Collections.Generic.IEnumerator。当前\t'System.Collections.Generic.IEnumerable '不包含'System'的定义,也没有接受第一个参数类型的扩展方法'System' 'System.Collections.Generic.IEnumerable '可以找到(你是否缺少使用指令或程序集引用?) –
JoeLA
2012-04-03 16:29:26