获取InvalidCastException取决于行数

时间：2016-01-18 05:31:42

标签： c# linq visual-studio casting

我在这个方法的返回行上得到了一个InvalidCastException 

        public List<ItemClass> getAll()
    {
        Console.WriteLine("Query");
        var list = (from i in db.Items
                    select i.getItem());
        Console.WriteLine("Done Query");
        return list.ToList<ItemClass>();
    }

我认为它与ToList方法有关。

有趣的是，我在表中有4条记录。查询返回所有这些（我知道它说.getItem（）。getItem返回一个Item类型的对象。现在当我在visual studio中按下继续时我得到4次InvalidCastException。在第5次我点击继续，我得到了输出预期。

这是异常文本+输出。

 A first chance exception of type 'System.InvalidCastException' occurred in System.Data.dll
    System.Transactions Critical: 0 : <TraceRecord xmlns="http://schemas.microsoft.com/2004/10/E2ETraceEvent/TraceRecord" Severity="Critical"><TraceIdentifier>http://msdn.microsoft.com/TraceCodes/System/ActivityTracing/2004/07/Reliability/Exception/Unhandled</TraceIdentifier><Description>Unhandled exception</Description><AppDomain>AppointmentBookingSystem.vshost.exe</AppDomain><Exception><ExceptionType>System.InvalidCastException, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</ExceptionType><Message>Specified cast is not valid.</Message><StackTrace>   at System.Data.SqlClient.SqlBuffer.get_Int32()
       at System.Data.SqlClient.SqlDataReader.GetInt32(Int32 i)
       at Read_ItemClass(ObjectMaterializer`1 )
       at System.Data.Linq.SqlClient.ObjectReaderCompiler.ObjectReader`2.MoveNext()
       at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
       at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
       at AppointmentBookingSystem.ServiceItems.getAll() in c:\Users\Kim\Documents\Visual Studio 2013\Projects\AppointmentBookingSystem\AppointmentBookingSystem\ServiceItems.cs:line 20
       at AppointmentBookingSystem.DatabaseExplorer.button1_Click(Object sender, EventArgs e) in c:\Users\Kim\Documents\Visual Studio 2013\Projects\AppointmentBookingSystem\AppointmentBookingSystem\DatabaseExplorer.cs:line 27
       at System.Windows.Forms.Control.OnClick(EventArgs e)
       at System.Windows.Forms.Button.OnClick(EventArgs e)
       at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
       at System.Windows.Forms.Control.WmMouseUp(Message&amp;amp; m, MouseButtons button, Int32 clicks)
       at System.Windows.Forms.Control.WndProc(Message&amp;amp; m)
       at System.Windows.Forms.ButtonBase.WndProc(Message&amp;amp; m)
       at System.Windows.Forms.Button.WndProc(Message&amp;amp; m)
       at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message&amp;amp; m)
       at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message&amp;amp; m)
       at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
       at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG&amp;amp; msg)
       at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.Run(Form mainForm)
       at AppointmentBookingSystem.Program.Main() in c:\Users\Kim\Documents\Visual Studio 2013\Projects\AppointmentBookingSystem\AppointmentBookingSystem\Program.cs:line 19
       at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
       at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
       at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
       at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
       at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       at System.Threading.ThreadHelper.ThreadStart()</StackTrace><ExceptionString>System.InvalidCastException: Specified cast is not valid.
       at System.Data.SqlClient.SqlBuffer.get_Int32()
       at System.Data.SqlClient.SqlDataReader.GetInt32(Int32 i)
       at Read_ItemClass(ObjectMaterializer`1 )
       at System.Data.Linq.SqlClient.ObjectReaderCompiler.ObjectReader`2.MoveNext()
       at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
       at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
       at AppointmentBookingSystem.ServiceItems.getAll() in c:\Users\Kim\Documents\Visual Studio 2013\Projects\AppointmentBookingSystem\AppointmentBookingSystem\ServiceItems.cs:line 20
       at AppointmentBookingSystem.DatabaseExplorer.button1_Click(Object sender, EventArgs e) in c:\Users\Kim\Documents\Visual Studio 2013\Projects\AppointmentBookingSystem\AppointmentBookingSystem\DatabaseExplorer.cs:line 27
       at System.Windows.Forms.Control.OnClick(EventArgs e)
       at System.Windows.Forms.Button.OnClick(EventArgs e)
       at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
       at System.Windows.Forms.Control.WmMouseUp(Message&amp;amp; m, MouseButtons button, Int32 clicks)
       at System.Windows.Forms.Control.WndProc(Message&amp;amp; m)
       at System.Windows.Forms.ButtonBase.WndProc(Message&amp;amp; m)
       at System.Windows.Forms.Button.WndProc(Message&amp;amp; m)
       at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message&amp;amp; m)
       at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message&amp;amp; m)
       at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
       at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG&amp;amp; msg)
       at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.Run(Form mainForm)
       at AppointmentBookingSystem.Program.Main() in c:\Users\Kim\Documents\Visual Studio 2013\Projects\AppointmentBookingSystem\AppointmentBookingSystem\Program.cs:line 19
       at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
       at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
       at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
       at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
       at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       at System.Threading.ThreadHelper.ThreadStart()</ExceptionString></Exception></TraceRecord>
    A first chance exception of type 'System.InvalidCastException' occurred in System.Data.dll
    System.Transactions Critical: 0 : <TraceRecord xmlns="http://schemas.microsoft.com/2004/10/E2ETraceEvent/TraceRecord" Severity="Critical"><TraceIdentifier>http://msdn.microsoft.com/TraceCodes/System/ActivityTracing/2004/07/Reliability/Exception/Unhandled</TraceIdentifier><Description>Unhandled exception</Description><AppDomain>AppointmentBookingSystem.vshost.exe</AppDomain><Exception><ExceptionType>System.InvalidCastException, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</ExceptionType><Message>Specified cast is not valid.</Message><StackTrace>   at System.Data.SqlClient.SqlBuffer.get_Int32()
       at System.Data.SqlClient.SqlDataReader.GetInt32(Int32 i)
       at Read_ItemClass(ObjectMaterializer`1 )
       at System.Data.Linq.SqlClient.ObjectReaderCompiler.ObjectReader`2.MoveNext()
       at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
       at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
       at AppointmentBookingSystem.ServiceItems.getAll() in c:\Users\Kim\Documents\Visual Studio 2013\Projects\AppointmentBookingSystem\AppointmentBookingSystem\ServiceItems.cs:line 20
       at AppointmentBookingSystem.DatabaseExplorer.button1_Click(Object sender, EventArgs e) in c:\Users\Kim\Documents\Visual Studio 2013\Projects\AppointmentBookingSystem\AppointmentBookingSystem\DatabaseExplorer.cs:line 27
       at System.Windows.Forms.Control.OnClick(EventArgs e)
       at System.Windows.Forms.Button.OnClick(EventArgs e)
       at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
       at System.Windows.Forms.Control.WmMouseUp(Message&amp;amp; m, MouseButtons button, Int32 clicks)
       at System.Windows.Forms.Control.WndProc(Message&amp;amp; m)
       at System.Windows.Forms.ButtonBase.WndProc(Message&amp;amp; m)
       at System.Windows.Forms.Button.WndProc(Message&amp;amp; m)
       at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message&amp;amp; m)
       at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message&amp;amp; m)
       at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
       at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG&amp;amp; msg)
       at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.Run(Form mainForm)
       at AppointmentBookingSystem.Program.Main() in c:\Users\Kim\Documents\Visual Studio 2013\Projects\AppointmentBookingSystem\AppointmentBookingSystem\Program.cs:line 19
       at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
       at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
       at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
       at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
       at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       at System.Threading.ThreadHelper.ThreadStart()</StackTrace><ExceptionString>System.InvalidCastException: Specified cast is not valid.
       at System.Data.SqlClient.SqlBuffer.get_Int32()
       at System.Data.SqlClient.SqlDataReader.GetInt32(Int32 i)
       at Read_ItemClass(ObjectMaterializer`1 )
       at System.Data.Linq.SqlClient.ObjectReaderCompiler.ObjectReader`2.MoveNext()
       at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
       at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
       at AppointmentBookingSystem.ServiceItems.getAll() in c:\Users\Kim\Documents\Visual Studio 2013\Projects\AppointmentBookingSystem\AppointmentBookingSystem\ServiceItems.cs:line 20
       at AppointmentBookingSystem.DatabaseExplorer.button1_Click(Object sender, EventArgs e) in c:\Users\Kim\Documents\Visual Studio 2013\Projects\AppointmentBookingSystem\AppointmentBookingSystem\DatabaseExplorer.cs:line 27
       at System.Windows.Forms.Control.OnClick(EventArgs e)
       at System.Windows.Forms.Button.OnClick(EventArgs e)
       at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
       at System.Windows.Forms.Control.WmMouseUp(Message&amp;amp; m, MouseButtons button, Int32 clicks)
       at System.Windows.Forms.Control.WndProc(Message&amp;amp; m)
       at System.Windows.Forms.ButtonBase.WndProc(Message&amp;amp; m)
       at System.Windows.Forms.Button.WndProc(Message&amp;amp; m)
       at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message&amp;amp; m)
       at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message&amp;amp; m)
       at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
       at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG&amp;amp; msg)
       at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.Run(Form mainForm)
       at AppointmentBookingSystem.Program.Main() in c:\Users\Kim\Documents\Visual Studio 2013\Projects\AppointmentBookingSystem\AppointmentBookingSystem\Program.cs:line 19
       at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
       at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
       at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
       at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
       at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       at System.Threading.ThreadHelper.ThreadStart()</ExceptionString></Exception></TraceRecord>
    A first chance exception of type 'System.InvalidCastException' occurred in System.Data.dll
    System.Transactions Critical: 0 : <TraceRecord xmlns="http://schemas.microsoft.com/2004/10/E2ETraceEvent/TraceRecord" Severity="Critical"><TraceIdentifier>http://msdn.microsoft.com/TraceCodes/System/ActivityTracing/2004/07/Reliability/Exception/Unhandled</TraceIdentifier><Description>Unhandled exception</Description><AppDomain>AppointmentBookingSystem.vshost.exe</AppDomain><Exception><ExceptionType>System.InvalidCastException, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</ExceptionType><Message>Specified cast is not valid.</Message><StackTrace>   at System.Data.SqlClient.SqlBuffer.get_Int32()
       at System.Data.SqlClient.SqlDataReader.GetInt32(Int32 i)
       at Read_ItemClass(ObjectMaterializer`1 )
       at System.Data.Linq.SqlClient.ObjectReaderCompiler.ObjectReader`2.MoveNext()
       at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
       at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
       at AppointmentBookingSystem.ServiceItems.getAll() in c:\Users\Kim\Documents\Visual Studio 2013\Projects\AppointmentBookingSystem\AppointmentBookingSystem\ServiceItems.cs:line 20
       at AppointmentBookingSystem.DatabaseExplorer.button1_Click(Object sender, EventArgs e) in c:\Users\Kim\Documents\Visual Studio 2013\Projects\AppointmentBookingSystem\AppointmentBookingSystem\DatabaseExplorer.cs:line 27
       at System.Windows.Forms.Control.OnClick(EventArgs e)
       at System.Windows.Forms.Button.OnClick(EventArgs e)
       at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
       at System.Windows.Forms.Control.WmMouseUp(Message&amp;amp; m, MouseButtons button, Int32 clicks)
       at System.Windows.Forms.Control.WndProc(Message&amp;amp; m)
       at System.Windows.Forms.ButtonBase.WndProc(Message&amp;amp; m)
       at System.Windows.Forms.Button.WndProc(Message&amp;amp; m)
       at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message&amp;amp; m)
       at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message&amp;amp; m)
       at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
       at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG&amp;amp; msg)
       at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.Run(Form mainForm)
       at AppointmentBookingSystem.Program.Main() in c:\Users\Kim\Documents\Visual Studio 2013\Projects\AppointmentBookingSystem\AppointmentBookingSystem\Program.cs:line 19
       at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
       at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
       at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
       at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
       at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       at System.Threading.ThreadHelper.ThreadStart()</StackTrace><ExceptionString>System.InvalidCastException: Specified cast is not valid.
       at System.Data.SqlClient.SqlBuffer.get_Int32()
       at System.Data.SqlClient.SqlDataReader.GetInt32(Int32 i)
       at Read_ItemClass(ObjectMaterializer`1 )
       at System.Data.Linq.SqlClient.ObjectReaderCompiler.ObjectReader`2.MoveNext()
       at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
       at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
       at AppointmentBookingSystem.ServiceItems.getAll() in c:\Users\Kim\Documents\Visual Studio 2013\Projects\AppointmentBookingSystem\AppointmentBookingSystem\ServiceItems.cs:line 20
       at AppointmentBookingSystem.DatabaseExplorer.button1_Click(Object sender, EventArgs e) in c:\Users\Kim\Documents\Visual Studio 2013\Projects\AppointmentBookingSystem\AppointmentBookingSystem\DatabaseExplorer.cs:line 27
       at System.Windows.Forms.Control.OnClick(EventArgs e)
       at System.Windows.Forms.Button.OnClick(EventArgs e)
       at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
       at System.Windows.Forms.Control.WmMouseUp(Message&amp;amp; m, MouseButtons button, Int32 clicks)
       at System.Windows.Forms.Control.WndProc(Message&amp;amp; m)
       at System.Windows.Forms.ButtonBase.WndProc(Message&amp;amp; m)
       at System.Windows.Forms.Button.WndProc(Message&amp;amp; m)
       at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message&amp;amp; m)
       at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message&amp;amp; m)
       at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
       at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG&amp;amp; msg)
       at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
       at System.Windows.Forms.Application.Run(Form mainForm)
       at AppointmentBookingSystem.Program.Main() in c:\Users\Kim\Documents\Visual Studio 2013\Projects\AppointmentBookingSystem\AppointmentBookingSystem\Program.cs:line 19
       at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
       at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
       at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
       at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
       at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       at System.Threading.ThreadHelper.ThreadStart()</ExceptionString></Exception></TraceRecord>
    Name 1 12
    Name2 2 12
    Name3 3 12
    Name4 4 12

itemClass时：

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

namespace AppointmentBookingSystem
{
    public class ItemClass
    {
        private int itemId;

        public int ItemId
        {
            get { return itemId; }
            set { itemId = value; }
        }
        private string itemName;

        public string ItemName
        {
            get { return itemName; }
            set { itemName = value; }
        }
        private double itemPrice;

        public double ItemPrice
        {
            get { return itemPrice; }
            set { itemPrice = value; }
        }

        public ItemClass(int idIn, string nameIn, double priceIn) 
        {
            itemId = idIn;
            itemName = nameIn;
            itemPrice = priceIn;
        }


    }
}

0 个答案:

没有答案
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