第二个Listview不显示任何信息(但具有滚动条) [英] Second Listview doesn't show any information (But it has a scrollbar)

问题描述

大家好，

我遇到了一个选项卡式Windows窗体的问题，该窗体应该在两个选项卡下显示不同的信息.该代码很好地填充了第一个列表视图，但是第二个仅显示了一个滚动条.到目前为止，这是我的代码.谢谢任何帮助这个新角的人.

我确实收到此错误:Microsoft.VisualBasic.dll中出现了类型为"System.ArgumentException"的第一次机会异常

Hi Everyone,

I am having trouble with a tabbed windows form that is supposed to display different information under two tabs. The code populates the first listview fine but the second one only shows a scroll bar. Here is my code so far. Thank you anyone who helps this greenhorn.

I do get this error: A first chance exception of type ''System.ArgumentException'' occurred in Microsoft.VisualBasic.dll

    Dim sCompanyID As String
    Dim sNameID As String

    Private ColumnsSet As Boolean = False
    Private Const ConnString As String = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=S:\Tracker\Tracker_Tables.mdb"
    Private cn As OleDbConnection = New OleDbConnection(ConnString)

    Private Sub frmCompanyProfile_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Me.CompanyTypesTableAdapter.Fill(Me.Tracker_TablesDataSet.CompanyTypes)
        Call FillForm()
        Call lvEmployeesFill()
        Call lvSalesFill()
    End Sub

    Private Sub lvEmployeesFill()

        Dim cmd As OleDbCommand
        cmd = New OleDbCommand("SELECT [NameID], [First], [Last] FROM [CustomerNames] WHERE [CompanyID]=" & sCompanyID, cn)
        Filllistview(lvEmployees, cmd)
    End Sub

    Private Sub lvSalesFill()

        Dim cmd As OleDbCommand
        cmd = New OleDbCommand("SELECT [CompanyID] FROM [Sales] WHERE [CompanyID]=" & sCompanyID, cn)
        Filllistview(LVSales, cmd)
    End Sub

Private Sub Filllistview(ByVal objListView As ListView, ByRef cmd As OleDbCommand)

        cn.Open()
        Dim RowList As ArrayList = New ArrayList()
        Dim reader As OleDbDataReader = cmd.ExecuteReader()
        Do While Reader.Read()
            Dim Values(Reader.FieldCount) As Object
            Reader.GetValues(Values)
            RowList.Add(Values)
        Loop

        If Not ColumnsSet Then
            Dim schema As DataTable = Reader.GetSchemaTable()
            SetColumnHeaders(objListView, schema)
        End If
        Reader.Close()
        cn.Close()

        PopulateList(objListView, RowList)
    End Sub

    Private Sub SetColumnHeaders(ByVal objListView As ListView, ByVal schema As DataTable)
        Dim row As DataRow

        objListView.View = View.Details
        For Each row In schema.Rows
            objListView.Columns.Add(row("ColumnName"), 100, HorizontalAlignment.Left)
        Next
        ColumnsSet = True
    End Sub

    Private Sub PopulateList(ByVal objListView As ListView, ByVal RowList As ArrayList)
        objListView.Items.Clear()

        Dim row As Object()
        For Each row In RowList
            Dim OrderDetails(row.Length) As String
            'Dim col As Object
            Dim ColIdx As Integer

            For ColIdx = 0 To row.Length - 1
                OrderDetails(ColIdx) = Convert.ToString(row(ColIdx))
            Next

            Dim NewItem As ListViewItem = New ListViewItem(OrderDetails)
            objListView.Items.Add(NewItem)
        Next
    End Sub

推荐答案

在"SetColumnHeaders(..)"中，为列表视图创建列.
这仅适用于第一个列表视图，因为您设置了ColumnsSet
填充第一个变量时将class变量设置为true.然后，当
填充第二个变量，此变量已设置为true，您
不要在第二个列表视图中再次执行此操作.

因此，您的listview可能有数据(您看到滚动条)，但是没有列.

那该例外呢?它在哪里抛出，什么为空?

Hi,

in "SetColumnHeaders(..)" you create the columns for your listviews.
That only works for the first listview, as you set the ColumnsSet
class variable to true while filling the first one. Then, when
filling the second one, this variable is already set to true and you
dont do it again for the second listview.

So, your listview may have data (you see scrollbars), but it has no columns.

And what about that exception? Where is it thrown, what is null?

非常感谢！！！我的学习还在继续.

〜杰克

Thank you so much!!! My learning continues.

~Jack

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