水平太差，虽然认为Linq是个好东东，但有谁能教教我，怎么调试？

想做个通过XML做配置的方案，使用Linq

<? xml version="1.0" encoding="utf-8" ?>
< root >
     < schedules >
         < idle > 3600000 </ idle >
         < schedule >
             < dic > e:\ </ dic >
             < schedulename > dhdp </ schedulename >
             < configfile > dhdpconfig.xml </ configfile >
         </ schedule >
         < schedule >
             < dic > e:\ </ dic >
             < schedulename > logdhdp </ schedulename >
             < configfile > logdhdpconfig.xml </ configfile >
         </ schedule >
     </ schedules >
</ root >

class  Schedule 
    {
         public   string  dic {  get ;  set ; }
         public   string  schedulename {  get ;  set ; }
         public   string  configfile {  get ;  set ; }
    }
     class  Schedules
    {
         public   int  Idle {  get ;  set ; }
         public  List < Schedule >  ScheduleList {  get ;  set ; }        
    }

     class  Program
    {
         static   void  Main( string [] args)
        {
            
            var xmlfn  =   @" Schedules.xml " ;        
            TestScheduleList(xmlfn);
            TestSchedulesList(xmlfn);
            TestSchedulesList2(xmlfn);
            Console.ReadKey();
        }
         public   static   void  TestScheduleList( string  xmlfn)
        {
            XElement SchedulesXml  =  XElement.Load(xmlfn);

            List < Schedule >  ScheduleList  =  (
                from ScheduleElement  in  SchedulesXml.Elements( " schedules " ).Descendants( " schedule " )
                select  new  Schedule
                {
                    dic  =  ScheduleElement.Element( " dic " ).Value,
                    schedulename  =  ScheduleElement.Element( " schedulename " ).Value,
                    configfile  =  ScheduleElement.Element( " configfile " ).Value                   
                }
            ).ToList();
            Console.WriteLine( " 测试ScheduleList " );
             foreach  (var sc  in  ScheduleList)
            {
                Console.WriteLine(sc.configfile);
            }
            Console.ReadKey();
        }
         public   static   void  TestSchedulesList( string  xmlfn)
        {
            XElement SchedulesXml  =  XElement.Load(xmlfn);
            var SchedulesList  =  from SchedulesElement  in  SchedulesXml.Elements( " schedules " )
                                select SchedulesElement;
            Console.WriteLine( " 测试SchedulesList " );
             foreach  (var scs  in  SchedulesList)
            {
                Console.WriteLine(scs.Value);
            }
            Console.ReadKey();
        }
         public   static   void  TestSchedulesList2( string  xmlfn)
        {
            XElement SchedulesXml  =  XElement.Load(xmlfn);
            var SchedulesList  =  from SchedulesElement  in  SchedulesXml.Elements( " schedules " )
                                select  new  Schedules
                                {
                                    Idle  =  ( int )SchedulesElement.Element( " Idle " ),
                                    ScheduleList  =  (
                                        from ScheduleElement  in  SchedulesElement.Descendants( " schedule " )
                                        select  new  Schedule
                                        {
                                            dic  =  ScheduleElement.Element( " dic " ).Value,
                                            schedulename  =  ScheduleElement.Element( " schedulename " ).Value,
                                            configfile  =  ScheduleElement.Element( " configfile " ).Value                                           
                                        }
                                     ).ToList()
                                };
            Console.WriteLine( " 测试SchedulesList " );
             foreach  (var scs  in  SchedulesList)
            {
                Console.WriteLine(scs.ScheduleList.ToString());
            }
            Console.ReadKey();
        }
    }

 

 

在使用TestSchedulesList2有错误，不知怎样调试，错误如下：

未处理 System.ArgumentNullException
  Message="值不能为空。\r\n参数名: element"
  Source="System.Xml.Linq"
  ParamName="element"
  StackTrace:
       在 System.Xml.Linq.XElement.op_Explicit(XElement element)
       在 ConsoleApplication1.Program.<TestSchedulesList2>b__7(XElement SchedulesElement) 位置 D:\web\ConsoleApplication1\ConsoleApplication1\Program.cs:行号 170
       在 System.Linq.Enumerable.WhereSelectEnumerableIterator`2.MoveNext()
       在 ConsoleApplication1.Program.TestSchedulesList2(String xmlfn) 位置 D:\web\ConsoleApplication1\ConsoleApplication1\Program.cs:行号 186
       在 ConsoleApplication1.Program.Main(String[] args) 位置 D:\web\ConsoleApplication1\ConsoleApplication1\Program.cs:行号 129
       在 System.AppDomain._nExecuteAssembly(Assembly assembly, String[] args)
       在 System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
       在 Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
       在 System.Threading.ThreadHelper.ThreadStart_Context(Object state)
       在 System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       在 System.Threading.ThreadHelper.ThreadStart()
  InnerException:

经过大家的提醒，终于找到原因了，XML是要区分大小写的，我将idle写成了Idle了，改后运行正常了。

public   static   void  TestSchedulesList2( string  xmlfn)
        {
            XElement SchedulesXml  =  XElement.Load(xmlfn);
            var SchedulesList  =  from SchedulesElement  in  SchedulesXml.Elements( " schedules " )
               select  new  Schedules
                {
                    Idle  =   int .Parse(SchedulesElement.Element( " idle " ).Value),
                    ScheduleList  =
                        (from ScheduleElement  in  SchedulesElement.Descendants( " schedule " )
                            select  new  Schedule
                            {
                                dic  =  ScheduleElement.Element( " dic " ).Value,
                                schedulename  =  ScheduleElement.Element( " schedulename " ).Value,
                                configfile  =  ScheduleElement.Element( " configfile " ).Value
                              }
                         ).ToList()
                };
            Console.WriteLine( " 测试SchedulesList " );
             foreach  (var scs  in  SchedulesList)
            {
                Console.WriteLine(scs.ScheduleList[ 0 ].schedulename);
            }
            Console.ReadKey();
        }

 

 

转载于:https://www.cnblogs.com/GDLMO/archive/2011/03/17/1987099.html