Question

我有一个listBox1，其中收集了项目。

以button1单击开始的timer1。

还有progressBar1

这是完整的代码。

private void button1_Click(object sender, EventArgs e)
{
    timer1.Enabled = true;
    timer1.Interval = 500;
    progressBar1.Maximum = listBox1.Items.Count;
}

private void timer1_Tick(object sender, EventArgs e)
{
    x.Send("<iq type='set' to='" + textBox6.Text + "@conference.jabber.com'>" + 
           "<query xmlns='http://jabber.org/protocol/muc#admin'>" +
           "<item jid='" + listBox1.Items[0].ToString() + 
           "@nimbuzz.com' affiliation='member'/></query></iq>");
    listBox1.Items.RemoveAt(0);
    progressBar1.Value += 1;
    groupBox4.Text = listBox1.Items.Count.ToString();
}

上面的代码运行良好但是当listBox1中剩下0项时，progressBar1停止出现错误

System.ArgumentOutOfRangeException未处理消息： InvalidArgument =＆＃39; 0＆＃39;的值对于＆＃39; index＆＃39;无效。参数名称：index

Answer 1

如何进行简单检查

if (listBox1.Items.Count > 0)
{
    listBox1.Items.RemoveAt(0);
}

Answer 2

试试这个

private void timer1_Tick(object sender, EventArgs e)
{
    if(listBox1.Items.Count > 0) {
 x.Send("<iq type='set' to='" + textBox6.Text + "@conference.jabber.com'><query xmlns='http://jabber.org/protocol/muc#admin'><item jid='" + listBox1.Items[0].ToString() + "@nimbuzz.com' affiliation='member'/></query></iq>");
        listBox1.Items.RemoveAt(0);
        progressBar1.Value += 1;
        groupBox4.Text = listBox1.Items.Count.ToString();
    }
}

Answer 3

我的答案与已发布的内容基本相同，但格式有所改善。最好使用string.Format()来帮助提高代码的可读性。

private void timer1_Tick(object sender, EventArgs e)
{
    if (listBox1.Items.Count > 0)
    {
        x.Send(string.Format(
            "<iq type='set' to='{0}@conference.jabber.com'><query xmlns='http://jabber.org/protocol/muc#admin'><item jid='{1}@nimbuzz.com' affiliation='member'/></query></iq>",
            textBox6.Text,
            listBox1.Items[0].ToString()));

        listBox1.Items.RemoveAt(0);
        progressBar1.Value += 1;
        groupBox4.Text = listBox1.Items.Count.ToString();
    }
}

删除项目时出现InvalidArgument异常

3 个答案: