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vb.net - 如何延迟在列表框中添加项目 vb.net

问题描述

我在 vb.net 中使用 for、while 和 do while 循环在列表框中添加一些值。我想使用计时器来延迟向列表框添加值。请告诉语法，我应该使用什么&以下是我的代码：

 Public Class Form1
    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click        
    Dim a As Integer
            For a = 1 To 10          
                    ListBox1.Items.Add(a)
     End If

            Next


        End Sub

        Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
            Dim b As Integer
            b = 4
            If b < 5 Then
                MessageBox.Show("eRROR")
            End If
            While b <= 3
                ListBox2.Items.Add(b)
                b = b + 1
            End While


        End Sub

        Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click
            Dim c As Integer
            c = 20
            Do
                c = c + 1
                ListBox3.Items.Add(c)
            Loop While c <= 30


        End Sub

        Private Sub ListBox1_SelectedIndexChanged(sender As Object, e As EventArgs) Handles ListBox1.SelectedIndexChanged

        End Sub

        Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load

        End Sub


    End Class

标签： vb.net

解决方案

计时器每n毫秒执行一次，您可以通过处理计时器的Tick 事件来利用这一点。如果您想跟踪您正在进行的增量，请在 Tick 事件的范围之外（请参阅此处）声明一个私有变量，或者在 Tick 事件内声明一个静态变量。

私有变量：

Private counter As Integer = 0
Private Sub Timer1_Tick(ByVal sender As Object, ByVal e As EventArgs) Handles Timer1.Tick
    counter += 1

    If (counter < 31) Then
        ListBox1.Items.Add(counter)
    Else
        Timer1.Stop()
    End If
End Sub

静态变量：

Private Sub Timer1_Tick(ByVal sender As Object, ByVal e As EventArgs) Handles Timer1.Tick
    Static counter As Integer = 0

    If (counter < 31) Then
        counter += 1
        ListBox1.Items.Add(counter)
    Else
        Timer1.Stop()
    End If
End Sub

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