带有输入验证的 Vb.Net 消息框

问题描述

所以我要买一台新的笔记本电脑来帮助我决定我想出了一个积分系统。我制作了一个应用程序来帮助计算，它由一系列复选框组成，这些复选框具有不同类别的组件等（cpu、RAM 等）的不同选项。他们会根据他们的表现获得分数。我有几行代码来检查每个类别是否选择了多个组件。如果超过 1 个，则会弹出一个消息框，告诉用户然后重置选项。但是，第一次访问后，消息框出现了两次。

错误视频：https://imgur.com/a/D9WSVO5

这是我的第一个 vb.net solo GUI 程序，所以请多多关照。

非常感谢， :)

Public Class Form1
Dim IS_R54500 As Boolean = False
Dim IS_R53500 As Boolean = False
Dim IS_R34300 As Boolean = False
Dim IS_Gb4 As Boolean = False
Dim IS_Gb8 As Boolean = False
Dim IS_Screen14 As Boolean = False
Dim IS_Screen15 As Boolean = False
Dim IS_SSD128 As Boolean = False
Dim IS_SSD256 As Boolean = False
Dim IS_SSD512 As Boolean = False
Dim IS_USBA As Integer = 0
Dim IS_USBC As Integer = 0
Dim IS_HDMI As Integer = 0
Dim IS_DP As Integer = 0
Dim Total As Integer = 0

Public Sub R54500_CheckedChanged(sender As Object,e As EventArgs) Handles R54500.CheckedChanged
    IS_R54500 = True
End Sub

Public Sub R53500_CheckedChanged(sender As Object,e As EventArgs) Handles R53500.CheckedChanged
    IS_R53500 = True
End Sub

Public Sub R34300_CheckedChanged(sender As Object,e As EventArgs) Handles R34300.CheckedChanged
    IS_R34300 = True
End Sub

Public Sub Gb4_CheckedChanged(sender As Object,e As EventArgs) Handles Gb4.CheckedChanged
    IS_Gb4 = True
End Sub

Public Sub Gb8_CheckedChanged(sender As Object,e As EventArgs) Handles Gb8.CheckedChanged
    IS_Gb8 = True
End Sub

Public Sub Screen14_CheckedChanged(sender As Object,e As EventArgs) Handles Screen14.CheckedChanged
    IS_Screen14 = True
End Sub

Public Sub Screen15_CheckedChanged(sender As Object,e As EventArgs) Handles Screen15.CheckedChanged
    IS_Screen15 = True
End Sub

Public Sub SSD128_CheckedChanged(sender As Object,e As EventArgs) Handles SSD128.CheckedChanged
    IS_SSD128 = True
End Sub

Public Sub SSD256_CheckedChanged(sender As Object,e As EventArgs) Handles SSD256.CheckedChanged
    IS_SSD256 = True
End Sub

Public Sub SSD512_CheckedChanged(sender As Object,e As EventArgs) Handles SSD512.CheckedChanged
    IS_SSD512 = True
End Sub

Public Sub USBA_TextChanged(sender As Object,e As EventArgs) Handles USBA.TextChanged
    IS_USBA = USBA.Text()
End Sub

Public Sub USBC_TextChanged(sender As Object,e As EventArgs) Handles USBC.TextChanged
    IS_USBC = USBC.Text()
End Sub

Public Sub HDMI_TextChanged(sender As Object,e As EventArgs) Handles HDMI.TextChanged
    IS_HDMI = HDMI.Text()
End Sub

Public Sub DP_TextChanged(sender As Object,e As EventArgs) Handles DP.TextChanged
    IS_DP = DP.Text()
End Sub

Public Sub Results_Click(sender As Object,e As EventArgs) Handles Results.Click
    Results.Text = CStr(Total)
End Sub

Public Sub Calculate_Click(sender As Object,e As EventArgs) Handles Calculate.Click
    Total = 0

    If IS_R54500 And IS_R53500 = True Then
        MessageBox.Show("There is more than one option chosen in a certain category." & vbCrLf & "Please fix this error and then try again.","Error")
        IS_R54500 = False
        IS_R53500 = False
        R54500.CheckState = CheckState.Unchecked
        R53500.CheckState = CheckState.Unchecked
    End If
    If IS_R54500 And IS_R34300 = True Then
        MessageBox.Show("There is more than one option chosen in a certain category." & vbCrLf & "Please fix this error and then try again.","Error")
        IS_R54500 = False
        IS_R34300 = False
        R54500.CheckState = CheckState.Unchecked
        R34300.CheckState = CheckState.Unchecked
    End If
    If IS_R53500 And IS_R34300 = True Then
        MessageBox.Show("There is more than one option chosen in a certain category." & vbCrLf & "Please fix this error and then try again.","Error")
        IS_R53500 = False
        IS_R34300 = False
        R53500.CheckState = CheckState.Unchecked
        R34300.CheckState = CheckState.Unchecked
    End If
    If IS_Gb8 And IS_Gb4 = True Then
        MessageBox.Show("There is more than one option chosen in a certain category." & vbCrLf & "Please fix this error and then try again.","Error")
        IS_Gb4 = False
        IS_Gb8 = False
        Gb4.CheckState = CheckState.Unchecked
        Gb8.CheckState = CheckState.Unchecked
    End If
    If IS_Screen14 And IS_Screen15 = True Then
        MessageBox.Show("There is more than one option chosen in a certain category." & vbCrLf & "Please fix this error and then try again.","Error")
        IS_Screen14 = False
        IS_Screen15 = False
        Screen14.CheckState = CheckState.Unchecked
        Screen15.CheckState = CheckState.Unchecked
    End If
    If IS_SSD128 And IS_SSD256 = True Then
        MessageBox.Show("There is more than one option chosen in a certain category." & vbCrLf & "Please fix this error and then try again.","Error")
        IS_SSD128 = False
        IS_SSD256 = False
        SSD128.CheckState = CheckState.Unchecked
        SSD256.CheckState = CheckState.Unchecked
    End If
    If IS_SSD128 And IS_SSD512 = True Then
        MessageBox.Show("There is more than one option chosen in a certain category." & vbCrLf & "Please fix this error and then try again.","Error")
        IS_SSD128 = False
        IS_SSD512 = False
        SSD128.CheckState = CheckState.Unchecked
        SSD512.CheckState = CheckState.Unchecked
    End If
    If IS_SSD512 And IS_SSD256 = True Then
        MessageBox.Show("There is more than one option chosen in a certain category." & vbCrLf & "Please fix this error and then try again.","Error")
        IS_SSD512 = False
        IS_SSD256 = False
        SSD512.CheckState = CheckState.Unchecked
        SSD256.CheckState = CheckState.Unchecked
    End If

    If IS_R54500 = True Then
        Total += 3
    End If
    If IS_R53500 = True Then
        Total += 2
    End If
    If IS_R34300 = True Then
        Total += 1
    End If
    If IS_Gb8 = True Then
        Total += 2
    End If
    If IS_Gb4 = True Then
        Total += 1
    End If
    If IS_Screen14 = True Then
        Total += 1
    End If
    If IS_Screen15 = True Then
        Total += 2
    End If
    If IS_SSD128 = True Then
        Total += 1
    End If
    If IS_SSD256 = True Then
        Total += 2
    End If
    If IS_SSD512 = True Then
        Total += 3
    End If
    Total += CInt(IS_USBA)
    Total += CInt(IS_USBC)
    Total += CInt(IS_HDMI)
    Total += CInt(IS_DP)

    ''MessageBox.Show("There is more than one option chosen in a certain category." & vbCrLf & "Please fix this error and then try again.","Error")

    Results.Text = Total
End Sub

结束课程

解决方法

尝试更换

Public Sub SSD512_CheckedChanged(sender As Object,e As EventArgs) Handles SSD512.CheckedChanged
    IS_SSD512 = True
End Sub

与

Public Sub SSD512_CheckedChanged(sender As Object,e As EventArgs) Handles SSD512.CheckedChanged
    IS_SSD512 = SSD512.Checked
End Sub

我认为问题是当表单加载时，它会调用取消选中框，因此您的变量变为 TRUE。

如果您使用正确的控件，您可以为自己节省大量代码。 RadioButton 只允许在容器中进行单个选择。容器可以是分组框或表单。

使用 NumericUpDown 将确保您获得端口区域的编号。用户可以将任何内容放入 TextBox。

我在按钮代码中多次使用了 GetSelectedRadioButton。此函数接受一个包含单选按钮的容器并返回选定的单选按钮。它通过一点 Linq 魔法来实现这一点，它检查容器中的每个单选按钮，直到在 .Checked = True 处找到一个。此单选按钮分配给 rb 并返回到调用代码。如果未找到选中的单选按钮，则返回 Nothing。

如果我们试图在单选按钮的 .Name 属性为 Nothing 时检查它，我们会得到可怕的 NRE（空引用异常）所以，我们要做的第一件事是检查返回的单选按钮 Is Nothing。如果用户没有做出选择，我们会显示一个消息框并退出子。

如果用户进行了选择，我们将使用 Select Case 或 If 语句来增加 Total。

当涉及到端口时，我们通过控件循环获取 Value 属性（Decimal）。要将其添加到 Total，必须先将其转换为 Integer。

最后显示总计。

Private Sub btnCalculate_Click(sender As Object,e As EventArgs) Handles btnCalculate.Click
    Dim Total As Integer
    Dim rb = GetSelectedRadioButton(gbProcessor)
    If rb Is Nothing Then
        MessageBox.Show("Please select a Processor.")
        Exit Sub
    Else
        Select Case GetSelectedRadioButton(gbProcessor).Name
            Case "rb545"
                Total += 3
            Case "rb535"
                Total += 2
            Case "rb343"
                Total += 1
        End Select
    End If
    Dim rb1 = GetSelectedRadioButton(gbMemory)
    If rb1 Is Nothing Then
        MessageBox.Show("Please select Memory")
        Exit Sub
    Else
        If rb1.Name = "rb4" Then
            Total += 1
        Else
            Total += 2
        End If
    End If
    Dim rb2 = GetSelectedRadioButton(gbScreenSize)
    If rb2 Is Nothing Then
        MessageBox.Show("Please select a Screen Size.")
        Exit Sub
    Else
        If rb2.Name = "rb14" Then
            Total += 1
        Else
            Total += 2
        End If
    End If
    Dim rb3 = GetSelectedRadioButton(gbStorage)
    If rb3 Is Nothing Then
        MessageBox.Show("Please select Storage size.")
        Exit Sub
    Else
        Select Case rb3.Name
            Case "rb128"
                Total += 1
            Case "rb256"
                Total += 2
            Case "rb512"
                Total += 3
        End Select
    End If
    For Each ctrl As NumericUpDown In gbPorts.Controls.OfType(Of NumericUpDown)
        Total += CInt(ctrl.Value)
    Next
    lblCalculate.Text = Total.ToString
End Sub

Private Function GetSelectedRadioButton(Container As Control) As RadioButton
    Dim rb = Container.Controls.OfType(Of RadioButton)().FirstOrDefault(Function(r) r.Checked = True)
    Return rb
End Function

logic-error messagebox messagebox user-interface vb.net vb.net