Question

我正在制作表单，其中名称字段只能包含字母，空格和退格。如果用户试图输入任何其他东西，它将由异常处理程序处理，但我将以标签的形式显示消息＆＃34; *只允许使用字母，空格和退格键。＆＃34;。但是，当用户尝试重新输入正确的密钥时，程序必须在文本字段附近移动警告消息，但我使用标签并尝试删除其文本或处理并删除整个对象仍然保留，因为它靠近该文本字段..请帮我修理一下。

代码在这里

Public Class Form1
    Dim Flag As Boolean = False
    Private Sub TxtName_KeyPress(ByVal sender As System.Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TxtName.KeyPress
        Dim Txt As Integer = Asc(e.KeyChar)

        Dim Lbl As New Label
        If (Txt < 65 Or Txt > 90) And (Txt < 97 Or Txt > 122) And Txt <> 8 And Txt <> 32 Then
            e.Handled = True
            Lbl.Text = "*Only Alphabets, Space and" & vbNewLine & "Backspace are allowed."
            Lbl.AutoSize = True
            Lbl.Name = "LblError"
            Lbl.ForeColor = Color.Red
            Lbl.Location = TxtName.Location + New Point(175, 0)
            GrpBxDataInput.Controls.Add(Lbl)
            Flag = True

        ElseIf Flag = True Then
           Lbl.Text = " "
            Lbl.Location = TxtName.Location + New Point(175, 0)
            'GrpBxDataInput.Controls.Remove(Lbl)
            'Lbl.Dispose()
            Flag = False!

        End If
    End Sub
End Class

Answer 1

如果我是对的，那么问题是，每次调用keypress-function时都会创建一个新标签。你最终得到了一堆标签我建议你按照我在你的问题评论中提到的那样做：在设计师中创建一个标签并将其切换（可见）：

Public Class Form1

...
// part of the designer block:
GrpBxDataInput.Controls.Add(MyWarningLabel)

  Private Sub TxtName_KeyPress(ByVal sender As System.Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TxtName.KeyPress
    Dim Txt As Integer = Asc(e.KeyChar)

    If (Txt < 65 Or Txt > 90) And (Txt < 97 Or Txt > 122) And Txt <> 8 And Txt <> 32 Then
      e.Handled = True
      MyWarningLabel.Text = "*Only Alphabets, Space and" & vbNewLine & "Backspace are allowed."
      MyWarningLabel.Visible = True
    Else
      MyWarningLabel.Text = ""
      MyWarningLabel.Visible = false
    End If
  End Sub
End Class

Answer 2

在vb [design]中添加新标签后，可以从代码中手动查看。这是解决方案：

Dim Flag As Boolean = False
Private Sub TxtName_KeyPress(ByVal sender As System.Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TxtName.KeyPress
    Dim Txt As Integer = Asc(e.KeyChar)

    If (Txt < 65 Or Txt > 90) And (Txt < 97 Or Txt > 122) And Txt <> 8 And Txt <> 32 Then
        e.Handled = True
        Lbl.Text = "*Only Alphabets, Space and" & vbNewLine & "Backspace are allowed."
        Lbl.AutoSize = True
        Lbl.ForeColor = Color.Red
        Lbl.Visible = True
        Flag = True

    ElseIf Flag = True Then
        Lbl.Visible = False
        Flag = False

    End If
End Sub

如何在VB.Net中手动替换或删除标签文本？

2 个答案: