vb.net - 如何在visual basic 2008中为下一个循环使用计时器

Question

我有一个案例，我需要生成数百万个唯一代码。为此，我创建了一个生成函数，其中生成随机数。我从 for 循环调用此函数并将生成的数字添加到列表框中。我的代码如下

  for i=1 to val(txtnumber.txt)
       mynum=generate()
  next

我在表单上创建了一个标签，我想在其中显示处理循环时经过的秒数。我使用定时器控制作为

     timer1.start()
     for i=1 to val(txtnumber.text)
        mynum=generate()
        listbox1.items.add(mynum)
     next
     timer1.stop

和 timer1_tick 功能

     Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
    Label1.Text = Val(Label1.Text) + 1
     End Sub

但是当我单击生成按钮时，会生成所有数字，但计时器不显示耗时。

我可能错过了一些东西，所以请帮帮我

Answer 1

这可能最好在 BackgroundWorker 中处理。在表格上放置一个并设置其WorkerReportsProgress=True .此外，在 ListBox 中放置一百万个数字可能不是一个好主意，所以我省略了这一点。

Private Sub Button1_Click(ByVal sender As Object, ByVal e As EventArgs) Handles Button1.Click
  Button1.Enabled = False
  BackgroundWorker1.RunWorkerAsync()
End Sub

Private Sub BackgroundWorker1_DoWork(ByVal sender As Object, ByVal e As DoWorkEventArgs) Handles BackgroundWorker1.DoWork
  Dim started As DateTime = Now
  For i As Integer = 1 To val(txtnumber.txt)
    mynum=generate()
    BackgroundWorker1.ReportProgress(i, Nothing)
  Next
  Dim ended As TimeSpan = Now.Subtract(started)
  BackgroundWorker1.ReportProgress(0, ended.TotalSeconds.ToString)
End Sub

Private Sub BackgroundWorker1_ProgressChanged(ByVal sender As Object, ByVal e As ProgressChangedEventArgs) Handles BackgroundWorker1.ProgressChanged
  If e.UserState IsNot Nothing Then
    Label1.Text = e.UserState.ToString()
  Else
    Label1.Text = e.ProgressPercentage.ToString
  End If
End Sub

Private Sub BackgroundWorker1_RunWorkerCompleted(ByVal sender As Object, ByVal e As RunWorkerCompletedEventArgs) Handles BackgroundWorker1.RunWorkerCompleted
  Button1.Enabled = True
End Sub

当工作人员报告 ProgressChanged 时，您的标签应该会正确更新。事件。