Question

帮助，我得到“InvalidArgument ='-1'的值对'index'无效。参数名称：索引“。我不知道哪个部分搞砸了。希望你们能帮帮我。谢谢你的进步。

  private void bankerCard_DrawItem(object sender, DrawItemEventArgs e)
   {
        e.DrawBackground();
        Brush myBrush = Brushes.Black;

        if (bankerCard.Items[e.Index].ToString().Contains("♥"))
            myBrush = Brushes.Red;
        else if (bankerCard.Items[e.Index].ToString().Contains("♦"))
            myBrush = Brushes.Red;
        else
            myBrush = Brushes.Black;

        e.Graphics.DrawString(((ListBox)sender).Items[e.Index].ToString(),
            e.Font, myBrush, e.Bounds, StringFormat.GenericDefault);

        e.DrawFocusRectangle();
    }

以上代码测试，没问题。问题发生在下面。任何线索？

   private void playerCard_DrawItem(object sender, DrawItemEventArgs e)
    {
        e.DrawBackground();
        Brush myBrush = Brushes.Black;

        switch (e.Index)
        {
            case 0:
                myBrush = Brushes.Red;
                break;
            case 1:
                myBrush = Brushes.Orange;
                break;
            case 2:
                myBrush = Brushes.Purple;
                break;
        }

        e.Graphics.DrawString(((ListBox)sender).Items[e.Index].ToString(),
            e.Font, myBrush, e.Bounds, StringFormat.GenericDefault);  `error over here`

        e.DrawFocusRectangle();
    }

Answer 1

错误是自解释的，可能此处e.Index值为-1，您尝试访问(ListBox)sender).Items[-1]

((ListBox)sender).Items[e.Index].ToString()

要解决此问题，您可以添加if语句来检查index是否大于-1：

if(e.Index >= 0)
{
   e.Graphics.DrawString(((ListBox)sender).Items[e.Index].ToString(),
        e.Font, myBrush, e.Bounds, StringFormat.GenericDefault)
}

InvalidArgument ='-1'的值对'index'无效。参数名称：index

1 个答案: