C# 字符串无法转换为System.Windows.Control.Label

我的Wpf应用程序中的代码行有问题。

label.Content=（string）nextfruit[“q_text”]我得到这个错误（类型“string”不能隐式转换为“System.Windows.Controls.Label”），我认为这应该像我所做的那样工作

这是我的代码

using System;
using System.IO;
using System.Net;
using System.Windows;
using System.Web.Script.Serialization;
using System.Collections.Generic;
using Newtonsoft.Json;
using System.Json;
using System.Linq;
using Newtonsoft.Json.Linq;

 namespace MMPI2_Test
  {
    /// <summary>
   /// Interaktionslogik für Patient.xaml
   /// </summary>
 public partial class Patient : Window
{
    public Patient()
    {
        InitializeComponent();
        Loaded += MyWindow_Loaded;
    }


    public String MyProperty { get; set; }

    public String Property { get; set; }

    private IEnumerator<JObject> Enumerator { get; set; }
    public bool HasNext { get; private set; }




    private void MyWindow_Loaded(object sender, RoutedEventArgs e)
    {
        dynamic convert = JsonConvert.DeserializeObject(MyProperty);

        string user = MyProperty;
        //lbuser.Content = json;


       //string tan = "";
        MainWindow main = new MainWindow();
        // main.alpha = tan;

        string html = string.Empty;
        string url = @"http://stidl.workcloud.at/?tag=question&token=" + Property;

        HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
        request.AutomaticDecompression = DecompressionMethods.GZip;

        using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
        using (Stream stream = response.GetResponseStream())
        using (StreamReader reader = new StreamReader(stream))
        {
            html = reader.ReadToEnd();
        }
        // dynamic magic = JsonConvert.DeserializeObject(html);
        // string json2 = new JavaScriptSerializer().Serialize(html);


        var j = new JavaScriptSerializer().DeserializeObject(user) as Dictionary<string, object>;
        var d = j["data"] as Dictionary<string, object>;
        lbuser.Content = d["fname"] + " " + d["lname"].ToString();

        //JObject QuestionObject = JObject.Parse(html);
        //JToken question = QuestionObject["data"].First["q_text"];
        //lbquestion.Content = question;

        JObject QuestionObject = JObject.Parse(html);
        Enumerator = QuestionObject["data"].Children<JObject>().GetEnumerator();

        JObject IDObject = JObject.Parse(html);
        JToken id = IDObject["data"].First["q_id"];
        JToken lastid = IDObject["data"].Last["q_id"];
        //JToken nextid = IDObject["data"].First.Next.Next["q_id"];
        lbid.Content = "Frage " + id + " von " + lastid;


    }

    class qq
    { 

    }

    private void bt_no_Click(object sender, RoutedEventArgs e)
    {

        string html = string.Empty;
        string url = @"http://stidl.workcloud.at/?tag=question&token=" + Property;

        HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
        request.AutomaticDecompression = DecompressionMethods.GZip;

        using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
        using (Stream stream = response.GetResponseStream())
        using (StreamReader reader = new StreamReader(stream))
        {
            html = reader.ReadToEnd();
        }
        //JObject IDObject = JObject.Parse(html);
        //JToken nextid = IDObject["data"].First["q_id"];
        ////int result = (int)nextid;
        //lbid.Content = nextid;

        HasNext = Enumerator.MoveNext();
        if (HasNext)
        {
            JObject QuestionObject = JObject.Parse(html);
            Enumerator = QuestionObject["data"].Children<JObject>().GetEnumerator();
            JObject nextfruit = Enumerator.Current;
            lbquestion = (string)nextfruit["q_text"];
        }
        else
        {

        }


    }

    private void bt_yes_Click(object sender, RoutedEventArgs e)
    {

    }

    //public class QuestionData
    //{
    //    public string Data { get; set; } // this will store the JSON string
    //    public List<Data> DataList { get; set; } // this will be the actually list. 
    //}

    //public class Data
    //{
    //    public string q_id { get; set; }
    //    public string q_text { get; set; }


    //}


 }
}

<Window x:Class="MMPI2_Test.Patient"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:local="clr-namespace:MMPI2_Test"
    mc:Ignorable="d"
    Title="Patient" Height="560" Width="980">
<Window.Background>
    <ImageBrush ImageSource="images/background.jpg" />
</Window.Background>

<Grid>
    <Label x:Name="lbquestion" Content="" HorizontalAlignment="Left" Margin="31,229,0,0" VerticalAlignment="Top" Width="906" Height="71"/>
    <Button x:Name="bt_yes" Content="Ja" HorizontalAlignment="Left" Margin="534,349,0,0" VerticalAlignment="Top" Width="75" Click="bt_yes_Click" />
    <Button x:Name="bt_no" Content="Nein" HorizontalAlignment="Left" Margin="389,349,0,0" VerticalAlignment="Top" Width="75" Click="bt_no_Click"/>
    <Label x:Name="lbuser" Content="" HorizontalAlignment="Left" Height="73" Margin="31,151,0,0" VerticalAlignment="Top" Width="906"/>
    <Label x:Name="lbid" Content="" HorizontalAlignment="Left" Height="50" Margin="31,69,0,0" VerticalAlignment="Top" Width="783"/>

</Grid>

使用系统；
使用System.IO；
Net系统；
使用System.Windows；
使用System.Web.Script.Serialization；
使用System.Collections.Generic；
使用Newtonsoft.Json；
使用System.Json；
使用System.Linq；
使用Newtonsoft.Json.Linq；
名称空间MMPI2_测试
{
/// 
///Interaktionslogik für Patient.xaml
/// 
公共部分类患者：窗口
{
公共病人（）
{
初始化组件（）；
已加载+=我的窗口已加载；
}
公共字符串MyProperty{get；set；}
公共字符串属性{get；set；}
私有IEnumerator枚举数{get；set；}
公共bool HasNext{get；private set；}
已加载私有void MyWindow_（对象发送方，路由目标）
{
dynamic convert=JsonConvert.DeserializeObject（MyProperty）；
字符串user=MyProperty；
//lbuser.Content=json；
//字符串tan=“”；
MainWindow main=新的MainWindow（）；
//main.alpha=tan；
string html=string.Empty；
字符串url=@“http://stidl.workcloud.at/?tag=question&token=“+财产；
HttpWebRequest请求=（HttpWebRequest）WebRequest.Create（url）；
request.AutomaticDecompression=DecompressionMethods.GZip；
使用（HttpWebResponse=（HttpWebResponse）request.GetResponse（））
使用（Stream=response.GetResponseStream（））
使用（StreamReader=新StreamReader（stream））
{
html=reader.ReadToEnd（）；
}
//dynamic magic=JsonConvert.DeserializeObject（html）；
//字符串json2=newJavaScriptSerializer（）.Serialize（html）；
var j=新的JavaScriptSerializer（）。反序列化对象（用户）作为字典；
var d=j[“数据”]作为字典；
lbuser.Content=d[“fname”]+“”+d[“lname”].ToString（）；
//JObject QuestionObject=JObject.Parse（html）；
//JToken question=QuestionObject[“数据”]。第一个[“q_text”]；
//内容=问题；
JObject QuestionObject=JObject.Parse（html）；
Enumerator=QuestionObject[“data”].Children（）.GetEnumerator（）；
JObject IDObject=JObject.Parse（html）；
JToken id=IDObject[“数据”]。第一个[“q_id”]；
JToken lastid=IDObject[“数据”]。Last[“q_id”]；
//JToken nextid=IDObject[“数据”]。First.Next.Next[“q_id”]；
lbid.Content=“Frage”+id+“von”+lastid；
}
qq类
{ 
}
私有无效bt\u否\u单击（对象发送方，路由目标）
{
string html=string.Empty；
字符串url=@“http://stidl.workcloud.at/?tag=question&token=“+财产；
HttpWebRequest请求=（HttpWebRequest）WebRequest.Create（url）；
request.AutomaticDecompression=DecompressionMethods.GZip；
使用（HttpWebResponse=（HttpWebResponse）request.GetResponse（））
使用（Stream=response.GetResponseStream（））
使用（StreamReader=新StreamReader（stream））
{
html=reader.ReadToEnd（）；
}
//JObject IDObject=JObject.Parse（html）；
//JToken nextid=IDObject[“数据”]。第一个[“q_id”]；
////int result=（int）nextid；
//lbid.Content=nextid；
HasNext=Enumerator.MoveNext（）；
如果（下一步）
{
JObject QuestionObject=JObject.Parse（html）；
Enumerator=QuestionObject[“data”].Children（）.GetEnumerator（）；
JObject nextfruit=枚举器.Current；
lbquestion=（字符串）nextfruit[“q_text”]；
}
其他的
{
}
}
私有无效bt_是_单击（对象发送方，路由目标）
{
}
//公共类问题数据
//{
//公共字符串数据{get；set；}//这将存储JSON字符串
//公共列表DataList{get；set；}//这将是实际的列表。
//}
//公共类数据
//{
//公共字符串q_id{get；set；}
//公共字符串q_text{get；set；}
//}
}
}

我的XML代码

using System;
using System.IO;
using System.Net;
using System.Windows;
using System.Web.Script.Serialization;
using System.Collections.Generic;
using Newtonsoft.Json;
using System.Json;
using System.Linq;
using Newtonsoft.Json.Linq;

 namespace MMPI2_Test
  {
    /// <summary>
   /// Interaktionslogik für Patient.xaml
   /// </summary>
 public partial class Patient : Window
{
    public Patient()
    {
        InitializeComponent();
        Loaded += MyWindow_Loaded;
    }


    public String MyProperty { get; set; }

    public String Property { get; set; }

    private IEnumerator<JObject> Enumerator { get; set; }
    public bool HasNext { get; private set; }




    private void MyWindow_Loaded(object sender, RoutedEventArgs e)
    {
        dynamic convert = JsonConvert.DeserializeObject(MyProperty);

        string user = MyProperty;
        //lbuser.Content = json;


       //string tan = "";
        MainWindow main = new MainWindow();
        // main.alpha = tan;

        string html = string.Empty;
        string url = @"http://stidl.workcloud.at/?tag=question&token=" + Property;

        HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
        request.AutomaticDecompression = DecompressionMethods.GZip;

        using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
        using (Stream stream = response.GetResponseStream())
        using (StreamReader reader = new StreamReader(stream))
        {
            html = reader.ReadToEnd();
        }
        // dynamic magic = JsonConvert.DeserializeObject(html);
        // string json2 = new JavaScriptSerializer().Serialize(html);


        var j = new JavaScriptSerializer().DeserializeObject(user) as Dictionary<string, object>;
        var d = j["data"] as Dictionary<string, object>;
        lbuser.Content = d["fname"] + " " + d["lname"].ToString();

        //JObject QuestionObject = JObject.Parse(html);
        //JToken question = QuestionObject["data"].First["q_text"];
        //lbquestion.Content = question;

        JObject QuestionObject = JObject.Parse(html);
        Enumerator = QuestionObject["data"].Children<JObject>().GetEnumerator();

        JObject IDObject = JObject.Parse(html);
        JToken id = IDObject["data"].First["q_id"];
        JToken lastid = IDObject["data"].Last["q_id"];
        //JToken nextid = IDObject["data"].First.Next.Next["q_id"];
        lbid.Content = "Frage " + id + " von " + lastid;


    }

    class qq
    { 

    }

    private void bt_no_Click(object sender, RoutedEventArgs e)
    {

        string html = string.Empty;
        string url = @"http://stidl.workcloud.at/?tag=question&token=" + Property;

        HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
        request.AutomaticDecompression = DecompressionMethods.GZip;

        using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
        using (Stream stream = response.GetResponseStream())
        using (StreamReader reader = new StreamReader(stream))
        {
            html = reader.ReadToEnd();
        }
        //JObject IDObject = JObject.Parse(html);
        //JToken nextid = IDObject["data"].First["q_id"];
        ////int result = (int)nextid;
        //lbid.Content = nextid;

        HasNext = Enumerator.MoveNext();
        if (HasNext)
        {
            JObject QuestionObject = JObject.Parse(html);
            Enumerator = QuestionObject["data"].Children<JObject>().GetEnumerator();
            JObject nextfruit = Enumerator.Current;
            lbquestion = (string)nextfruit["q_text"];
        }
        else
        {

        }


    }

    private void bt_yes_Click(object sender, RoutedEventArgs e)
    {

    }

    //public class QuestionData
    //{
    //    public string Data { get; set; } // this will store the JSON string
    //    public List<Data> DataList { get; set; } // this will be the actually list. 
    //}

    //public class Data
    //{
    //    public string q_id { get; set; }
    //    public string q_text { get; set; }


    //}


 }
}

<Window x:Class="MMPI2_Test.Patient"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:local="clr-namespace:MMPI2_Test"
    mc:Ignorable="d"
    Title="Patient" Height="560" Width="980">
<Window.Background>
    <ImageBrush ImageSource="images/background.jpg" />
</Window.Background>

<Grid>
    <Label x:Name="lbquestion" Content="" HorizontalAlignment="Left" Margin="31,229,0,0" VerticalAlignment="Top" Width="906" Height="71"/>
    <Button x:Name="bt_yes" Content="Ja" HorizontalAlignment="Left" Margin="534,349,0,0" VerticalAlignment="Top" Width="75" Click="bt_yes_Click" />
    <Button x:Name="bt_no" Content="Nein" HorizontalAlignment="Left" Margin="389,349,0,0" VerticalAlignment="Top" Width="75" Click="bt_no_Click"/>
    <Label x:Name="lbuser" Content="" HorizontalAlignment="Left" Height="73" Margin="31,151,0,0" VerticalAlignment="Top" Width="906"/>
    <Label x:Name="lbid" Content="" HorizontalAlignment="Left" Height="50" Margin="31,69,0,0" VerticalAlignment="Top" Width="783"/>

</Grid>



if（HasNext）
{
JObject QuestionObject=JObject.Parse（html）；
Enumerator=QuestionObject[“data”].Children（）.GetEnumerator（）；
JObject nextfruit=枚举器.Current；
lbquestion=（string）nextfruit[“q_text”]；//lbquestion是一个标签
}

在我看来，这应该是设置内容。这甚至是你在问题中所说的。
更新：我没有注意到问题是一个标签

（string）nextfruit[“q_text”]
是试图强制转换字符串
lbQuestion.Content
是您要转换为字符串时需要访问的内容；错误是告诉您您试图将标签等同于字符串，而事实并非如此
 
lbquestion
是一个
标签
控件。OP包括定义它的XAML。哦，你是对的，但这实际上也解释了它。我会修正我的答案。很抱歉成为一个PITA，但关于C#中强制转换运算符的优先级，您也错了：使用
lbquestion.Content=（string）nextfruit[“q#text”]
设置标签的文本。不过，您还有其他错误（
Enumerator.MoveNext）没问题，每个人有时都会忽略一些简单的错误。