e.After.VoiceChannel.Name Discord.NET - 找不到空錯誤

在您判斷我發佈ANOTHER NullReferenceException問題之前，請閱讀我的代碼。我一直在使用Google的NullReferenceException錯誤一段時間，並沒有解釋爲什麼這個特定的部分給我一個錯誤。e.After.VoiceChannel.Name Discord.NET - 找不到空錯誤

if (e.After.VoiceChannel.Name != null)

我也看過Discord.NET的文檔，但也沒有任何結果。這是整個文件。

using Discord; 
using Discord.Commands; 

using System; 
using System.Collections.Generic; 
using System.Linq; 
using System.Text; 
using System.Threading.Tasks; 

namespace DiscBot 
{ 
    class myBot 
    { 
     DiscordClient discord; 

     public myBot() 
     { 

      discord = new DiscordClient(x => 
      { 
       x.LogLevel = LogSeverity.Info; 
       x.LogHandler = Log; 
      }); 

      discord.UsingCommands(x => 
      { 
       x.PrefixChar = '~'; 
       x.AllowMentionPrefix = true; 
       x.HelpMode = HelpMode.Public; 
      }); 

      var commands = discord.GetService<CommandService>(); 

      commands.CreateCommand("greet") 
       .Description("Does a thing") 
       .Parameter("theGreeted", ParameterType.Unparsed) 
       .Do(async (e)=> 
       { 
        var msgtoRead = e.Channel.DownloadMessages(1); 

        await e.Channel.SendTTSMessage("Hello " + e.GetArg("theGreeted")); 
       }); 

      discord.UserUpdated += async (s, e) => { 
       var channel = e.Server.FindChannels("general", ChannelType.Text).FirstOrDefault(); 
       string usrnm = e.After.Name; 

       // This shouldn't get an error 
       // But when I run the code I 
       // get a Null Reference Exception 

       if (e.After.VoiceChannel.Name != null) 
       { 
        await channel.SendMessage(usrnm + " to " + e.After.VoiceChannel.Name); 
       } 
       else 
       { 

        await channel.SendMessage(usrnm + " exited"); 
       } 
      }; 


      discord.UserJoined += async (s, e) => 
      { 
       var channel = e.Server.FindChannels("mainbois", ChannelType.Text).FirstOrDefault(); 
       var user = e.User; 
       await channel.SendTTSMessage(string.Format("Another human has entered...")); 
      }; 

      discord.ExecuteAndWait(async() => 
      { 
       await discord.Connect("MYBOTTOKEN", TokenType.Bot); 
      }); 
     } 

     private void Log(object sender, LogMessageEventArgs e) 
     { 
     Console.WriteLine(e.Message); 
     } 
    } 
}

任何幫助，非常感謝。提前致謝！

P.S.如果我在某個地方犯了一個簡單的錯誤，請懲罰。：P

來源

2017-04-22 ExoticDoom

編輯：'e.After.VoiceChannel'爲空。我不知道這個事件足以說明原因。 –

發現我不能檢查

if (e.After.VoiceChannel.Name != null)

如果VoiceChannel爲null。換句話說，我無法檢查基於null的值（如果這是有意義的）。我的新代碼看起來像

if (e.After.VoiceChannel != null)

感謝任何花時間看我的代碼的人。：D

來源

2017-04-22 21:18:31 ExoticDoom

e.After.VoiceChannel.Name Discord.NET - 找不到空錯誤

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