小编Ser*_*erg的帖子

当网络连接丢失3分钟或更长时间时,下面的WPF代码将永久挂起.当连接恢复时,它既不会抛出也不会继续下载或超时.如果网络连接在较短的时间内丢失(例如半分钟),则在连接恢复后会丢失.如何让网络中断更加强大？

using System;
using System.Net;
using System.Net.NetworkInformation;
using System.Windows;

namespace WebClientAsync
{

    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();

            NetworkChange.NetworkAvailabilityChanged +=
                (sender, e) => Dispatcher.Invoke(delegate()
                    {
                        this.Title = "Network is " + (e.IsAvailable ? " available" : "down");
                    });
        }

        const string SRC = "http://ovh.net/files/10Mio.dat";
        const string TARGET = @"d:\stuff\10Mio.dat";

        private async void btnDownload_Click(object sender, RoutedEventArgs e)
        {
            btnDownload.IsEnabled = false;
            btnDownload.Content = "Downloading " + SRC;
            try {
                using (var wcl = new WebClient())
                { …

图像显示问题:Venus项目已滚动但其选择是可见的.

我在ListView中查看了Hanged listSelector,我正在使用形状/渐变,但是仍然没有运气.

设备:适用于Android的MS VS Emulator,Android 4.2 XHDPI API-17
IDE:适用于Windows 7 WM的Android Studio 2.

布局,主要活动

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <ListView
        android:id="@android:id/list"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:choiceMode="singleChoice"
        android:drawSelectorOnTop="false"
        android:scrollingCache="false"
        android:animationCache="false"
        android:listSelector="@drawable/list_selector">
    </ListView>

</LinearLayout>

列表选择器

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item
        android:state_pressed="true"
        android:drawable="@drawable/item_pressed" />
    <item
        android:drawable="@drawable/item_selected" />
</selector>

drawables,item_pressed

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle" >
    <gradient
        android:angle="90"
        android:endColor="#0000ff"
        android:startColor="#0000ff" />

</shape>

item_selected

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle" >
    <gradient
        android:angle="90"
        android:endColor="#00ff00" …

在判断此问题已得到回答之前，请阅读说明。我在下面有这个简单的代码：

Dictionary<string, object> d = new Dictionary<string, object>();

d.Add("key" , 30d);

System.Diagnostics.Debug.WriteLine($" TYPE OF OBJECT IS  \"{d["key"].GetType()}\"");

netPlannedHours = (float)d["key"];         ---> **Line of Interest**

当我执行这个我得到：

对象的类型为“ System.Double”。引发异常：DevOpsAutomatedReporting.dll中的“ System.InvalidCastException”无法将类型为“ System.Double”的对象转换为类型为“ System.Single”。

例外是由标记为“兴趣线”的最后一行引起的。我真的不明白为什么最后一行会导致这种情况，因为在运行时将对象的类型推断为“ System.Double”，因此它应该将其强制转换为浮点数，但事实并非如此。有趣的一点是，如果我用以下两行代码之一替换最后一行（“感兴趣的行”），它将成功将double转换为float

// Cast the double object to double again and then to float **WORKS**
netPlannedHours = (float)(double)d["key"];

// Convert to float using "Convert.ToSingle()"  **WORKS**
netPlannedHours = Convert.ToSingle(d["key"]);

请对此有所启发。谢谢！

VS20019 创建了一个面向 .net 框架（即 .net 4.7.2）的 windows 窗体项目作为“旧”样式项目。我已使用Project2015To2017.Migrate2019.Tool将新创建的项目转换为 SDK 样式。转换后的项目运行正常，但 VS20019Add/New item对话框没有显示 Winforms 部分和表单模板。仍然 VS2017Add/New item对话框成功显示 Winforms 部分。以及 VS20019 为“旧”风格的原始项目所做的。

我缺少什么？转换项目：

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <OutputType>WinExe</OutputType>
    <TargetFramework>net472</TargetFramework>
    <AutoGenerateBindingRedirects>true</AutoGenerateBindingRedirects>
    <GenerateAssemblyInfo>false</GenerateAssemblyInfo>
    <OutputPath>bin\$(Configuration)\</OutputPath>
  </PropertyGroup>
  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
    <DebugType>full</DebugType>
  </PropertyGroup>
  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
    <DebugType>pdbonly</DebugType>
  </PropertyGroup>
  <ItemGroup>
    <Reference Include="System.Data.DataSetExtensions" />
    <Reference Include="Microsoft.CSharp" />
    <Reference Include="System.Deployment" />
    <Reference Include="System.Net.Http" />
    <Reference Include="System.Windows.Forms" />
  </ItemGroup>
  <ItemGroup>
    <Compile Update="Form1.cs">
      <SubType>Form</SubType>
    </Compile>
    <Compile Update="Form1.Designer.cs">
      <DependentUpon>Form1.cs</DependentUpon>
    </Compile>
    <EmbeddedResource Update="Properties\Resources.resx"> …

我得到了这个SELECT.我想计算(或总和？)玩家的黄牌和红牌(只有YellowCard = 1时才计数黄牌,而RedCard = 1时只计算红牌)..此SELECT无法正常工作.它即使有0或NULL也会计数卡.我该如何纠正它？

SELECT Firstname, Lastname, COUNT(YellowCard) AS Yellow, COUNT(RedCard) AS Red, Team.Name 
FROM PlayerMatch 
Inner join Player On PlayerMatch.PlayerId = Player.PlayerId 
INNER JOIN Team ON Player.TeamId = Team.TeamId 
INNER JOIN Match ON PlayerMatch.MatchId = Match.MatchId 
WHERE(YellowCard = 1 OR RedCard = 1) 
GROUP BY Lastname, Firstname, Name 
ORDER BY Yellow DESC