将项目添加到列表框，然后在30秒后删除

Question

I am trying to add a tag ID (RFID) to a listbox and then remove it after 30 seconds. What is the best way to do this?

txtTagID.Text = s1.Replace(" ", "").ToLower();
if (lstTagsHold.Items.Contains(txtTagID.Text) == false)
{
   lstTagsHold.Items.Add(txtTagID.Text);
}

Answer 1

尝试使用计时器控件（如果使用的是winforms）

Answer 2

// Declare the timer
private static System.Timers.Timer objTimer = new System.Timers.Timer(30000);

// Attach the event handler
objTimer.Elapsed += OnTimedElapsed;


private static void OnTimedElapsed(Object source, System.Timers.ElapsedEventArgs e)
    {
        lstTagsHold.Items.Remove(txtTagID.Text);
    }

Answer 3

Drop a System.Windows.Forms.Timer on your form and set the interval to around 1 second (or less depending on accuracy required). Declare the ExpiringItem class to store the time the entry was added. In your timer_click event check for expired items and remove.

class ExpiringItem
{
    private string text;
    public ExpiringItem(string text)
    {
        this.text = text;
        this.Added = DateTime.Now;
    }
    public DateTime Added { get; private set; }
    public override string ToString()
    {
        return text;
    }
}

private void timer1_Tick(object sender, EventArgs e)
{
    for (int i = listBox1.Items.Count -1; i > -1; i--)
    {
        var exp = (ExpiringItem)listBox1.Items[i];
        var timeVisible = DateTime.Now - exp.Added;
        if (timeVisible.TotalSeconds > 30)
            listBox1.Items.RemoveAt(i);

    }
}

To add items to your ListBox do

lstTagsHold.Items.Add(new ExpiringItem(txtTagID.Text));