尝试清除组合框时出现 ArgumentOutOfRangeException

Question

我在组合框上尝试运行.Clear() 时出现以下错误消息：

'System.ArgumentOutOfRangeException' 类型的第一次机会异常发生在 System.Windows.Forms.dll {"InvalidArgument='-1' 的值对 'index' 无效。参数名称：index"}

奇怪的是，它在转到应用程序中的新 'page' 之前执行了 .Clear()，并且没有问题。一旦我在 'page' 上，在组合框中绘制项目并尝试转到应用程序的下一个 'page'，它再次调用带有 clear 的函数并在到达时爆炸.Clear()。如果我在下面的代码中注释掉 cbo.DrawMode = DrawMode.OwnerDrawFixed 它也会像往常一样运行s ，所以问题肯定是在组合框中绘制字符串（我正在绘制字符串改变它们的颜色）。无论如何，完全不知道如何解决这个问题，我们将不胜感激。

代码如下：

-我的清除方法

Public Sub ClearCombos()
    'Clear Applicant Combos

    cboPrimary.Items.Clear() 'crashes when it hits this line
    cboJoin1.Items.Clear()
    cboJoin2.Items.Clear()
    cboJoin3.Items.Clear()
    cboJoin4.Items.Clear()
End Sub

在组合框中绘制字符串

Sub CheckForAgeOverage()

c_applicants = {cboPrimary, cboJoin1, cboJoin2, cboJoin3, cboJoin4}

Dim curdate As Date = Date.Now
Dim age As Integer

counter = 0
'Check age of applicants
For Each cbo As ComboBox In c_applicants
    If CKeyValuePair.GetComboBoxSelectedKey(c_applicants(counter), True) = instApplicant.applicantId Then
        age = Math.Floor(DateDiff(DateInterval.Month, DateValue(instApplicant.BirthDate), curdate) / 12)
        If age >= 70 Then
            overArray.Add(CKeyValuePair.GetComboBoxSelectedValue(c_applicants(counter)))
        End If
        cbo.DrawMode = DrawMode.OwnerDrawFixed

    Else
        For Each j As JoinsBU In instJoins
            If CKeyValuePair.GetComboBoxSelectedKey(c_applicants(counter), True) = j.Applicant.applicantId Then
                age = Math.Floor(DateDiff(DateInterval.Month, DateValue(j.Applicant.BirthDate), curdate) / 12)
                If age >= 70 Then
                    overArray.Add(CKeyValuePair.GetComboBoxSelectedValue(c_applicants(counter)))
                End If
                cbo.DrawMode = DrawMode.OwnerDrawFixed
            End If
        Next
    End If
    counter += 1
Next
End Sub

组合框 DrawItem 事件：

Private Sub cbo_DrawItem(sender As System.Object, e As System.Windows.Forms.DrawItemEventArgs) Handles cboPrimary.DrawItem, cboJoin1.DrawItem, cboJoin2.DrawItem, cboJoin3.DrawItem, cboJoin4.DrawItem

Dim brush As Brush = Brushes.Black

Dim text As String = (CType(sender, ComboBox)).Items(e.Index).ToString()
counter = 0

For Each s As String In overArray
    If text = overArray(counter) Then
        brush = Brushes.Red
    Else
        brush = Brushes.Black
    End If
    counter += 1
Next

e.Graphics.DrawString(sender.Items(e.Index).ToString(), e.Font, brush, _
e.Bounds, StringFormat.GenericDefault)
counter = 0

End Sub

Answer 1

这看起来不应该发生，但显然是这样。实际错误可能在 DrawItem 处理程序的这一行中：

Dim text As String = (CType(sender, ComboBox)).Items(e.Index).ToString()

尝试将赋值从 Dim 语句中分离出来，并检查 e.Index 的值以确保它是非负的。如果这是问题所在，您可能可以使用 if 来解决它，以确保 e.Index 是非负数。

尝试清除组合框时出现 ArgumentOutOfRangeException

ArgumentOutOfRangeException when trying to clear combobox

vb.net

combobox

exception