为什么在vb.net中我必须按两次键盘上的Escape

Question

我正在使用 DropdownStyle Combobox：Dropdown

如果我按 Enter 键盘，那么只按一次，但为什么如果我按 Escape 键盘，则必须执行两次，

我使用 String.Equals 方法通过参考文本框来检查组合框中选择的值是否正确。

为什么我必须按两次键盘上的 Esc 键？

或者我还有其他方法吗

我的代码有问题吗？

请指导我

谢谢

Public Class Form4
    Private count As Integer = 1
Protected Overrides Function ProcessCmdKey(ByRef msg As Message, ByVal keyData As Keys) As Boolean
        If keyData.ToString() = "Escape" Then
            If count = 1 Then
                count += 1
                Label1.Text = "You are pressing key escape once"
            ElseIf count = 2 Then
                Label1.Text = "You are pressing key escape twice"
            End If

        End If
        Return MyBase.ProcessCmdKey(msg, keyData)
    End Function
 Public Sub New()
        ' This call is required by the designer.
        InitializeComponent()

        ' Add any initialization after the InitializeComponent() call.

        ComboBox1.AutoCompleteMode = AutoCompleteMode.SuggestAppend
        ComboBox1.AutoCompleteSource = AutoCompleteSource.CustomSource
    End Sub
    Private Sub Form4_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        ComboBox1.AutoCompleteCustomSource = AutoSuggestList()
    End Sub
    Private Function AutoSuggestList() As AutoCompleteStringCollection
        Dim collection As New AutoCompleteStringCollection
        Using connection As New OleDbConnection(GetOledbConnectionString())
            collection.AddRange(connection.Query(Of String)("SELECT ColorCode FROM ColorCode").ToArray)
        End Using
        Return collection
    End Function

    Private Sub GetItemData(ByVal iditem As String)
        Dim item = COLORCODESERVICE.GetByColorcode2(iditem)
        If item IsNot Nothing Then
            If String.Equals(iditem, item.Colorcode, StringComparison.CurrentCultureIgnoreCase) Then
                ComboBox1.Text = item.Colorcode
            End If
            TextBox1.Text = item.Colorname
        Else
            MsgBox("Not Found Colorcode...")
            ComboBox1.ResetText()
            TextBox1.Clear()
            Return
        End If
    End Sub
 Private Sub ComboBox1_KeyDown(sender As Object, e As KeyEventArgs) Handles ComboBox1.KeyDown
        If e.KeyCode = Keys.Enter Or e.KeyCode = Keys.Escape Then
            GetItemData(ComboBox1.Text)
        ElseIf e.KeyCode = Keys.Back Then
            ComboBox1.ResetText()
            TextBox1.Clear()
        End If
    End Sub
End Class

Answer 1

通常您使用组合框来选择有效值。

将此与您拥有的进行比较，

Public Class Form1

    Private Sub Form1_Shown(sender As Object, e As EventArgs) Handles Me.Shown
        Dim items() As String = {"one", "two", "three", "four", "five"} 'test items
        ComboBox1.DataSource = items 'change to your data
        ComboBox1.AutoCompleteMode = AutoCompleteMode.SuggestAppend
        ComboBox1.AutoCompleteSource = AutoCompleteSource.ListItems '<<<<<<<<<<<<<<<
    End Sub

    Private Sub ComboBox1_SelectedIndexChanged(sender As Object, e As EventArgs) Handles ComboBox1.SelectedIndexChanged
        Debug.Write("SI ")
        TextBox1.Text = ComboBox1.SelectedValue.ToString
    End Sub

    Private Sub ComboBox1_TextChanged(sender As Object, e As EventArgs) Handles ComboBox1.TextChanged
        'the user is typing in ComboBox
        'if they press enter over a valid entry the
        '  .SelectedIndexChanged event will fire
        Debug.WriteLine("TC ")
        TextBox1.Text = "" 'blsnk is invalid
    End Sub
End Class