Question

我遇到TextBox1.TextChanged事件的问题。我的代码：

Private Sub TextBox1_TextChanged(sender As Object, e As EventArgs) Handles TextBox1.TextChanged
    MsgBox("txt was changed")
    TextBox1.Clear()
End Sub

问题是MsgBox显示两次，但我想只显示一次并清除TextBox。我怎样才能做到这一点？

Answer 1

两种方式：

暂时删除处理程序以防止再次触发事件：

Private Sub TextBox1_TextChanged(sender As Object, e As EventArgs) Handles TextBox1.TextChanged
    MsgBox("txt was changed")
    RemoveHandler TextBox1.TextChanged, AddressOf TextBox1_TextChanged
    TextBox1.Clear()
    AddHandler TextBox1.TextChanged, AddressOf TextBox1_TextChanged
End Sub

或

创建一个字段以检查事件是否源自自身：

Dim textBoxAlreadyChanging As boolean = False

Private Sub TextBox1_TextChanged(sender As Object, e As EventArgs) Handles TextBox1.TextChanged
    If Not textBoxAlreadyChanging Then
        MsgBox("txt was changed")
        textBoxAlreadyChanging = True
        TextBox1.Clear()
        textBoxAlreadyChanging = False
    End If
End Sub

TextBox1.TextChanged事件显示两次MsgBox

1 个答案: