带有 TabControl 的按钮不起作用

Question

我在 Form1 中放置了 label1、richTextBox1、Button1 和 Button2； 然后我写了下面的代码；一切正常，除了 Button1 和 button2 不工作； 知道为什么吗？

Public Class Form1

Private Sub TabControl1_SelectedIndexChanged(ByVal sender As Object, _
    ByVal e As System.EventArgs) Handles TabControl1.SelectedIndexChanged

    Select Case TabControl1.SelectedIndex
        Case 0 'first tab
            RichTextBox1.Clear() : RichTextBox1.AppendText("I'm on the first tab" & vbCrLf)
            '...
            With TabControl1.SelectedTab.Controls
                .Add(RichTextBox1)
                .Add(Label1)
                .Add(Button1)
            End With
        Case 1 'second tab
            RichTextBox1.Clear() : RichTextBox1.AppendText("Now; I'm on the Second tab" & vbCrLf)
            '...
            With TabControl1.SelectedTab.Controls
                .Add(RichTextBox1)
                .Add(Button2)
            End With
    End Select
End Sub

Private Sub Button1_Click(sender As Object, e As EventArgs)
    For s = 1 To 100
        RichTextBox1.AppendText(" Button1 - " & s & vbCrLf)
    Next
End Sub

Private Sub Button2_Click(sender As Object, e As EventArgs)
    For s = 1 To 100
        RichTextBox1.AppendText(" Button2 - " & s & vbCrLf)
    Next
End Sub

结束类

Answer 1

您的按钮单击处理程序似乎失去了与按钮的关联。要么复制粘贴代码而不连接处理程序，要么在对象的“事件”窗格中取消选择处理程序。只需将Handles 子句添加回如下：

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    For s = 1 To 100
        RichTextBox1.AppendText(" Button1 - " & s & vbCrLf)
    Next
End Sub

见：Handles Clause (MSDN)

顺便说一句，您还应该认真考虑在您的项目选项中启用 ON Option Explicit 和 Option Strict。这些可以关闭以与旧版 VB 代码兼容，但它们鼓励草率的代码，这可能会导致头痛和麻烦。使用这些选项，您的处理程序将如下所示：

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    Dim s As Integer   ' Option explicit - must declare all variables!
    For s = 1 To 100
        RichTextBox1.AppendText(" Button1 - " & s.ToString() & vbCrLf)
        ' Option strict -> no implicit casting of types (ie : int to string ^^)
    Next
End Sub