Question

from我在组合框A，B，C，D，E，F，G中有以下项目，我想按下按键以检查选择了哪个项目组合框我尝试

Private Sub kbHook_KeyDown(ByVal Key As System.Windows.Forms.Keys) Handles kbHook.KeyDown
 `If My.Computer.Keyboard.CtrlKeyDown AndAlso
    My.Computer.Keyboard.AltKeyDown AndAlso
    My.Computer.Keyboard.ShiftKeyDown AndAlso
          ComboBox2.SelectedValue.ToString then ` 
'some stuff 
end if
end sub

在组合框中，我选择A（ctrl + alt + shft + A），但出现空错误

Answer 1

kbHook_KeyDown在程序在后台运行时使用，我认为您想显示自己的表单，希望对您有所帮助

Private Sub kbHook_KeyDown(ByVal Key As System.Windows.Forms.Keys) Handles kbHook.KeyDown
    Select Case CStr(ComboBox2.SelectedItem)
        Case "A"
            If My.Computer.Keyboard.CtrlKeyDown AndAlso
    My.Computer.Keyboard.AltKeyDown AndAlso
    My.Computer.Keyboard.ShiftKeyDown AndAlso
    Key = Keys.A Then
              form1.show
                Me.BackColor = Color.Indigo

            End If
        Case "B"
            If My.Computer.Keyboard.CtrlKeyDown AndAlso
    My.Computer.Keyboard.AltKeyDown AndAlso
    My.Computer.Keyboard.ShiftKeyDown AndAlso
    Key = Keys.B Then
            form1.show
                Me.BackColor = Color.Indigo

            End If
        Case "C"
            If My.Computer.Keyboard.CtrlKeyDown AndAlso
    My.Computer.Keyboard.AltKeyDown AndAlso
    My.Computer.Keyboard.ShiftKeyDown AndAlso
    Key = Keys.C Then
                form1.show
                Me.BackColor = Color.Indigo

                 Case Else
                Me.Hide()

End Select
            End If

Answer 2

要检查ComboBox中的选定项目，请不要处理KeyDown事件，而要处理SelectedIndexChanged事件。 SelectedItem属性包含所选项目。

Private Sub ComboBox1_SelectedIndexChanged(sender As Object, e As EventArgs) _
    Handles ComboBox1.SelectedIndexChanged

    Select Case CStr(ComboBox1.SelectedItem)
        Case "A"
            MessageBox.Show("First case")
        Case "B"
            MessageBox.Show("Second case")
        Case "C"
            MessageBox.Show("etc.")
        Case "D"
        Case "E"
        Case "F"
        Case "G"
        Case Else
    End Select
End Sub

带组合框的KeyDown

2 个答案: