计时器未在vb.net中初始化 [英] Timer not initializing in vb.net

问题描述

您好我有一个使用excel作为数据源的vb.net程序。然后，我使用此数据源填充datagridview，并通过datagridview对数据集进行更改。我正在尝试通过一个按钮来刷新此数据集，该按钮将在更改后更新值。我唯一的问题是我正在尝试在我的刷新方法中设置一个计时器，但它从不初始化/启动。我无法弄清楚为什么，从我在网上找到的，在vb.net中启动计时器的方法是将timer变量设置为enabled = true。我已经进入调试器，发现计时器永远不会启动。以下是我的代码，如果有人能够弄清楚为什么这个计时器没有启动我会非常感谢你的帮助！





'声明我的计时器变量

  Dim  mytimer  As  新 System.Timers.Timer 
  Sub  refresh（）
 
 write2Size（）
 
 
 
 mytimer.timer = < span class =code-keyword>新 System.Timers.Timer（ 20000 ）
  ' 启动计时器 
 mytimer.Enabled =  True  
光标。 Current = Cursors.WaitCursor 
 
 
 
  AddHandler  mytimer.Elapsed， AddressOf  OnTimedEvent 
 
 
 
 objworkbook.Save（）
 objExcel.ActiveWorkbook.Save（）
 
 myDS.Clear（ ）
 retrieveUpdate（）
 
 ' 将光标设置回正常值 
 Cursor.Current =游标。默认 
 结束  Sub  
 
 私人 共享  Sub  OnTimedEvent（source  As   Object ，e  As  ElapsedEventArgs）
 
 Console.WriteLine（& quot; Elapsed  event 在{ 0 }，e.SignalTime）
 结束  Sub  

解决方案

这对我有用。计时器每20秒触发一次 Elapsed 事件。

  Dim  mytimer  As  新 System.Timers.Timer 
  Sub  MyRefresh（）
 write2Size（）
 mytimer = 新 System.Timers.Timer（ 20000 ）
 ' 启动计时器 
  AddHandler  mytimer.Elapsed， AddressOf  OnTimedEvent 
 mytimer.Enabled =  True  
 
 Cursor.Current = Cursors.WaitCursor 
 
 objworkbook.Save（）
 objExcel.ActiveWorkbook.Save（）
 
 myDS.Clear（）
 retrieveUpdate（）
 
 ' 将光标设置回来这里正常 
 Cursor.Current =游标。默认 
 结束  Sub  
 
 私人 共享  Sub  OnTimedEvent（source  As   Object ，e  As  ElapsedEventArgs）
 Console.WriteLine（  Elapsed事件的引发时间为{0}，e.SignalTime）
 结束 子 

Hello I have a vb.net program that uses excel as a datasource. I then fill a datagridview with this datasource and make changes to the dataset via the datagridview. I'm trying to find a way to refresh this dataset via a button that will update the values after a change. My only problem is that I'm trying to set up a timer in my refresh method but it never initializes/starts. I can't figure out why, from what I've found online the way to start a timer in vb.net is to set the timer variable to enabled = true. I've stepped into my debugger and found that the timer never starts. Here is my code below, if there is anyone who can figure out why this timer isn't starting I would greatly appreciate your help!


'declare my timer variable

Dim mytimer As New System.Timers.Timer
Sub refresh()
      
       write2Size()
       


       mytimer.timer = New System.Timers.Timer(20000)
      'Starting Timer
       mytimer.Enabled = True
       Cursor.Current = Cursors.WaitCursor


     
       AddHandler mytimer.Elapsed, AddressOf OnTimedEvent

       
 
       objworkbook.Save()
       objExcel.ActiveWorkbook.Save()

       myDS.Clear()
       retrieveUpdate()

'Setting the cursor back to normal here
       Cursor.Current = Cursors.Default
   End Sub

   Private Shared Sub OnTimedEvent(source As Object, e As ElapsedEventArgs)
    
       Console.WriteLine("The Elapsed event was raised at {0}, e.SignalTime)
   End Sub

解决方案

This works for me. The timer fires the Elapsed event every twenty seconds.

Dim mytimer As New System.Timers.Timer
Sub MyRefresh()
    write2Size()
    mytimer = New System.Timers.Timer(20000)
    'Starting Timer
    AddHandler mytimer.Elapsed, AddressOf OnTimedEvent
    mytimer.Enabled = True
    
    Cursor.Current = Cursors.WaitCursor

    objworkbook.Save()
    objExcel.ActiveWorkbook.Save()

    myDS.Clear()
    retrieveUpdate()

    'Setting the cursor back to normal here
    Cursor.Current = Cursors.Default
End Sub

Private Shared Sub OnTimedEvent(source As Object, e As ElapsedEventArgs)
    Console.WriteLine("The Elapsed event was raised at {0}", e.SignalTime)
End Sub

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