Question

我尝试根据我combobox（包含combobox列中的第一个datagridview的选择，为我的第二个textbox添加值）。

这是我的代码：

Private Sub DataGridView1_EditingControlShowing(sender As Object, e As System.Windows.Forms.DataGridViewEditingControlShowingEventArgs) Handles DataGridView1.EditingControlShowing
    Try
        'Sub Recurrence combobox is selected
        If DataGridView1.CurrentCell.ColumnIndex = 4 Then
            'Verify what is chosen in the Recurrence textbox
            Dim rowIndex = DataGridView1.CurrentCell.RowIndex
            Dim FirstComboboxValue = DataGridView1(3, rowIndex).Value

            If Not IsNothing(FirstComboboxValue) Then
                Dim cmb As ComboBox = TryCast(e.Control, ComboBox)
                RemoveHandler cmb.SelectedIndexChanged, New EventHandler(AddressOf ComboBox_SelectedIndexChanged)
                AddHandler cmb.SelectedIndexChanged, New EventHandler(AddressOf ComboBox_SelectedIndexChanged)
            End If
        End If
    Catch ex As Exception
        MsgBox(ex.ToString())
    End Try
End Sub

我的处理程序触发朝向ComboBox_SelectedIndexChanged事件的触发器：

Private Sub ComboBox_SelectedIndexChanged(ByVal sender As Object, ByVal e As EventArgs)
    If DataGridView1.CurrentCell.ColumnIndex = 4 Then
        Dim comboBox As ComboBox = CType(sender, ComboBox)
        Dim cbCell As DataGridViewComboBoxCell = DirectCast(DataGridView1.Rows(DataGridView1.CurrentCell.RowIndex).Cells(4), DataGridViewComboBoxCell)
        Dim rowIndex = DataGridView1.CurrentCell.RowIndex
        Dim FirstComboboxValue = DataGridView1(3, rowIndex).Value

        'Clear items so they don't keep adding on each other
        cbCell.Items.Clear()

        Select Case FirstComboboxValue
            Case "Choice1"
                cbCell.Items.Add("Item1")
                cbCell.Items.Add("Item2")
            Case "Choice2"
                cbCell.Items.Add("Item3")
                cbCell.Items.Add("Item4")
            Case "Choice3"
                cbCell.Items.Add("Item5")
            Case "Choice4"
                cbCell.Items.Add("Item6")
                cbCell.Items.Add("Item7")
        End Select

        'Remove event handler to prevent memory leak
        RemoveHandler comboBox.SelectedIndexChanged, AddressOf ComboBox_SelectedIndexChanged
    End If
End Sub

出于某种原因，当我使用断点并逐步执行该程序时，只有在第二次尝试打开＆＃34;项目＆＃34时，才会在第二个combobox中添加这些项目; combobox。

如果我尝试在没有调试的情况下运行程序，则不显示任何内容。知道我做错了吗？

Answer 1

如果您在ComboBox中使用SelectedIndexChanged，即使您没有单击ComboBox，也可能遇到触发事件的问题。

当您打开和关闭Windows窗体时会发生这种情况。

使用 SelectionChangeCommitted 事件为此更好。

当所选项目发生更改并且组合框中显示更改时，会发生SelectionChangeCommitted事件。

通过使用SelectionChangeCommitted事件，您无需声明RemoveHandler和AddHandler语句。

另一种可能性：

尝试使用处理cmb.SelectedIndexChanged

有几种方法可以在VB.NET中声明事件。通常使用的是handle关键字。

Private Sub ComboBox_SelectedIndexChanged(ByVal sender As Object,
            ByVal e As EventArgs) Handles cmb.SelectedIndexChanged

Datagridview Control修改另一个

1 个答案: