Question

尝试在我的组合框上运行.Clear（）时出现以下错误消息：

类型＆＃39; System.ArgumentOutOfRangeException＆＃39;的第一次机会异常。发生在System.Windows.Forms.dll中 {＆＃34; InvalidArgument =＆＃39; -1＆＃39;的值对于＆＃39; index＆＃39;无效。参数名称：index＆＃34;}

奇怪的是，在进入新的＆＃39;页面之前，它会执行.Clear（）。在应用程序中，它没有问题。进入＆＃39;页面＆＃39;后，在组合框中绘制项目，然后尝试转到下一页＆＃39;在应用程序中，它再次调用带有clear的函数，当它到达.Clear（）时会爆炸。如果我在下面的代码中注释掉cbo.DrawMode = DrawMode.OwnerDrawFixed它也会正常运行，所以问题肯定是在组合框中绘制字符串（我在绘制字符串以改变它们的颜色）。无论如何，完全难以理解如何解决这个问题，任何帮助将不胜感激。

代码如下：

- 我清楚的方法

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

Comboboxes 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

看起来这不应该发生，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()

尝试将分配从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，你可以用if来解决它，以确保e.Index是非负的。

尝试清除组合框时ArgumentOutOfRangeException

1 个答案: