在winform应用程序中,如果列表框为空或项小于0,如何停止计时器
本文关键字:小于 何停止 计时器 应用程序 winform 如果 列表 | 更新日期: 2023-09-27 18:06:03
我正在制作一个windows应用程序。
- 一个按钮1,从服务器开始获取listBox1中的项目。
- 启动定时器的按钮2。
- 从listBox1中删除项的计时器。
- 显示进程进度的progressBar1。
代码如下:
private void button1_Click(object sender, EventArgs e)
{
jabber.Send("<iq type='get' to='" + textBox1.Text + "@conference.jabber.com' id='qip_1026'><query xmlns='http://jabber.org/protocol/muc#admin'><item affiliation='outcast' /></query></iq>");
}
private void button2_Click(object sender, EventArgs e)
{
progressBar1.Maximum = listBox1.Items.Count;
timer1.Start();
timer1.Interval = 4000;
}
private void timer1_Tick(object sender, EventArgs e)
{
if (listBox1.Items.Count > 0)
{
jabber.Send("<iq type='set' to='" + textBox7.Text + "@conference.jabber.com'><query xmlns='http://jabber.org/protocol/muc#admin'><item jid='" + listBox1.Items[0].ToString() + "' affiliation='none'/></query></iq>");
listBox1.Items.RemoveAt(0);
progressBar1.Value += 1;
label.Text = listBox1.Items.Count.ToString();
}
else
{
timer1.Enabled = False;
}
}
上面的代码工作得很好,直到listBox1中还剩下一个项目。
错误是:
系统。未处理ArgumentOutOfRangeExceptionMessage=InvalidArgument= '0'的值对'index'无效。参数名称:index
当listBox1达到0时抛出错误。我想在listbox1为空或没有项或0项时停止计时器
问题在这段代码中:
private void timer1_Tick(object sender, EventArgs e)
{
if (listBox1.Items.Count > 0)
{
jabber.Send("<iq type='set' to='" + textBox7.Text + "@conference.jabber.com'><query xmlns='http://jabber.org/protocol/muc#admin'><item jid='" + listBox1.Items[0].ToString() + "' affiliation='none'/></query></iq>");
listBox1.Items.RemoveAt(0);
progressBar1.Value += 1;
label.Text = listBox1.Items.Count.ToString();
}
else
{
timer1.Enabled = False;
}
}
所以正在发生的事情是,你正在使用count检查>0,然后调用jabber来做工作,如果调用变得缓慢-你会看到多个计时器被解雇。所以那里会排起长队。您需要在这里稍微修改一下代码,使用lock来保存列表,并允许jabber执行其工作:
private void timer1_Tick(object sender, EventArgs e)
{
lock (listBox1)
{
if (listBox1.Items.Count > 0)
{
jabber.Send("<iq type='set' to='" + textBox7.Text +
"@conference.jabber.com'><query xmlns='http://jabber.org/protocol/muc#admin'><item jid='" +
listBox1.Items[0].ToString() + "' affiliation='none'/></query></iq>");
listBox1.Items.RemoveAt(0);
progressBar1.Value += 1;
label.Text = listBox1.Items.Count.ToString();
}
else
{
timer1.Enabled = False;
}
}
}
Lock也将确保项目被正确删除。按照下面的注释保存文件:
public class ChatHistoryManager
{
private readonly RichTextBox richTextBox;
private Timer timer = new Timer();
public ChatHistoryManager(RichTextBox richTextBox)
{
this.richTextBox = richTextBox;
this.InitializeTimer();
}
public string Location { get; set; }
private void InitializeTimer()
{
this.timer.Tick += timer_Tick;
this.timer.Enabled = true;
this.timer.Interval = (int) TimeSpan.FromHours(1).TotalMilliseconds;
}
void timer_Tick(object sender, EventArgs e)
{
this.SaveFile();
}
public void SaveFile()
{
//Save the file to the location
this.richTextBox.SaveFile(this.Location,RichTextBoxStreamType.RichText);
}
public void Stop()
{
this.timer.Stop();
}
}
现在我们需要这样设置格式:
private void Form1_Load(object sender, EventArgs e)
{
ChatHistoryManager chatHistoryManager = new ChatHistoryManager(this.richTextBox1);
chatHistoryManager.Location = @"C:'Development'test.txt";
}
try this
int count = City.Items.Count - 1;
for (int i = count; i > 0; i--){
City.Items.RemoveAt(i);
}
我是这么做的。
private void button1_Click(object sender, EventArgs e)
{
jabber.Send("<iq type="get" to="" + textBox1.Text + "@conference.jabber.com" id="qip_1026"><query xmlns="http://jabber.org/protocol/muc#admin"><item affiliation="outcast" /></query></iq>");
}
private void button2_Click(object sender, EventArgs e)
{
progressBar1.Maximum = listBox1.Items.Count;
progressBar1.Value = 0;
// Set the timer interval to four seconds
timer1.Interval = 4000;
// Start the timer
timer1.Start();
}
private void timer1_Tick(object sender, EventArgs e)
{
// Disable the timer while we are working in this procedure so
// it doesn't tick while we are working in this procedure
timer1.Enabled = False;
// Send only if there are items in the ListBox
if (listBox1.Items.Count > 0)
{
jabber.Send("<iq type="set" to="" + textBox7.Text + "@conference.jabber.com"><query xmlns="http://jabber.org/protocol/muc#admin"><item jid="" + listBox1.Items[0].ToString() + "" affiliation="none" /></query></iq>");
listBox1.Items.RemoveAt(0);
progressBar1.Value += 1;
label.Text = listBox1.Items.Count.ToString();
}
// Re-enable only if there are items left in the ListBox
if (listBox1.Items.Count > 0)
{
timer1.Enabled = True;
}
}