vb.net - 如何将组合框项目转换为值并计算它
问题描述
我想将组合框中的选定项目转换为数字并计算它。
当我尝试启动我的 vb.net 程序时,我收到了这样的消息。
从字符串“< 20”到类型“Integer”的转换无效
任何帮助是极大的赞赏。
这是我的代码:
Private Sub SaveBtn_Click(sender As Object, e As EventArgs) Handles SaveBtn.Click
Dim LHR As Integer
Dim TipeRetak As Integer
Dim LbRetak As Integer
Dim LuKer As Integer
Dim Alur As Integer
Dim Tambal As Integer
Dim Kasar As Integer
Dim amblas As Integer
Select Case ComboLHR.SelectedIndex
Case "< 20 "
LHR = 0
Case "20 - 50"
LHR = 1
Case "50 - 200"
LHR = 2
Case "200 - 500"
LHR = 3
Case "500 - 2000"
LHR = 4
Case "2000 - 5000"
LHR = 5
Case "5000 - 20000"
LHR = 6
Case "20000 - 50000"
LHR = 7
Case "> 50000"
LHR = 8
End Select
Select Case ComboTipeRetak.SelectedIndex
Case "Buaya"
TipeRetak = 5
Case "Acak"
TipeRetak = 4
Case "Melintang"
TipeRetak = 3
Case "Memanjang"
TipeRetak = 1
Case "Tidak Ada"
TipeRetak = 1
End Select
Select Case ComboLebarRetak.SelectedIndex
Case "> 2 mm"
LbRetak = 3
Case "1 - 2 mm"
LbRetak = 2
Case "< 1 mm"
LbRetak = 1
Case "Tidak Ada"
LbRetak = 0
End Select
Select Case ComboLuasKerusakan.SelectedIndex
Case "> 30%"
LuKer = 3
Case "10 - 30%"
LuKer = 2
Case "< 10%"
LuKer = 1
Case "0"
LuKer = 0
End Select
Select Case ComboKedalamanAlur.SelectedIndex
Case "> 20 mm"
Alur = 7
Case "11 - 20 mm"
Alur = 5
Case "6 - 10 mm"
Alur = 3
Case "0 - 5 mm"
Alur = 1
Case "Tidak Ada"
Alur = 0
End Select
Select Case ComboTambal.SelectedIndex
Case ">30 %"
Tambal = 3
Case "20 - 30 %"
Tambal = 2
Case "10 - 20%"
Tambal = 1
Case "< 10%"
Tambal = 0
End Select
Select Case ComboKekasaran.SelectedIndex
Case "Desintegration"
Kasar = 4
Case "Pelepasan Butir"
Kasar = 3
Case "Rough(Hungry)"
Kasar = 2
Case "Fatty"
Kasar = 1
Case "Close Texture"
Kasar = 0
End Select
Select Case ComboAmblas.SelectedIndex
Case "> 5/100 m"
amblas = 4
Case "2 - 5/100 m"
amblas = 2
Case "0 - 2/100 m"
amblas = 1
Case "Tidak Ada"
amblas = 0
End Select
Dim comand As New MySqlCommand("INSERT INTO `tb_bnkt`(`nomor`, `Nama`, `kondisi prioritas`) VALUES (@nomor,@NamaRuas,@kondisi)", Connector)
comand.Parameters.Add("@nomor", MySqlDbType.VarChar).Value = TextNomor.Text
comand.Parameters.Add("@NamaRuas", MySqlDbType.VarChar).Value = ComboNamaRuas.Text
comand.Parameters.Add("@kondisi", MySqlDbType.VarChar).Value = 17 - (Val(LHR + TipeRetak + LbRetak + LuKer + Alur + Tambal + Kasar + amblas))
If comand.ExecuteNonQuery() = 1 Then
MessageBox.Show("Data disimpan")
Loading()
TextNomor.Clear()
ComboNamaRuas.Text = String.Empty
ComboLHR.Text = String.Empty
ComboTipeRetak.Text = String.Empty
ComboLebarRetak.Text = String.Empty
ComboLuasKerusakan.Text = String.Empty
ComboKedalamanAlur.Text = String.Empty
ComboTambal.Text = String.Empty
ComboKekasaran.Text = String.Empty
ComboAmblas.Text = String.Empty
Else
MessageBox.Show("Error")
End If
End Sub
解决方案
通过简单的类和数据绑定,您可以稍微简化代码并摆脱当前的问题。
Public Class MyItem
Public ReadOnly Name As String
Public ReadOnly Value As Integer
Public Sub New(name As String, value As Integer)
Me.Name = name
Me.Value = value
End Sub
End Class
' Then in constructor create collection of values and bind it ot the combobox
Dim LHRValues As New List(Of MyItem) From
{
New MyItem("< 20 ", 0),
New MyItem("20 - 50", 1),
New MyItem("50 - 200", 2),
New MyItem("200 - 500", 3),
New MyItem("500 - 2000", 4),
New MyItem("2000 - 5000", 5),
New MyItem("5000 - 20000", 6),
New MyItem("20000 - 50000", 7),
New MyItem("> 50000", 8)
}
ComboLHR.DisplayMember = "Name" ' Property Name will be used as a text
ComboLHR.ValueMember = "Value" ' Property Value will be used as a value
ComboLHR.DataSource = LHRValues
' Then in the code where you need selected value
Private Sub SaveBtn_Click(sender As Object, e As EventArgs) Handles SaveBtn.Click
Dim selectedLHR As Integer = DirectCast(ComboLHR.SelectedValue, Integer)
' Other selected values
End Sub
您只需要转换ComboLHR.SelectedValue
为您期望的类型 ( Integer
),因为SelectedValue
它的类型是object
。我希望你已经Option Strict
设置了On
。
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