How can I update the value of a Label control periodically?

问题

I'm trying to make a label display some text, and then after a short while refresh itself and be able to re-display something else later. At the moment however I don't know how to make a label pause (if at all possible).

My code so far:

foreach (var x in mod)
{
      labelWARNING.Visible = true;
      labelWarningMessage.Text = "This module has a prerequisite module: " + x;
      //need a pause here to give user sufficient time to read the above text
      //labelWarningMessage.Text = "";
}

回答1:

From your questions, it seems you need to change the value of something like a status label to display information periodically to the user. If you are using winforms, you can use a timer and a delegate like this:

//First create a delegate to update the label value
public delegate void labelChanger(string s);

//create timer object
Timer t = new Timer();

//create a generic List to store messages. You could also use a Queue instead.
List<string> mod = new List<string>();

//index for list
int cIndex = 0;

//add this in your Form Load event or after InitializeComponent()
t.Tick += (timer_tick);
t.Interval = 5000;//how long you want it to stay.
t.Start();

//the timer_tick method
private void timer_tick(object s, EventArgs e)
{
     labelWarningMessage.Invoke(new labelChanger(labelWork), mod[cIndex]);
     cIndex++;
}

//the method to do the actual message display
private void labelWork(string s)
{
     labelWARNING.Visible = true;
     labelWarningMessage.Text = "This module has a prerequisite module: " + s;
}

I hope that helps. Good Luck.

EDIT: Thought I posted this code long ago only to come back and find out I didn't...but maybe someone might find it useful.

Also, this method will be redundant in this case, since creating the Timer alone will work without the use of a delegate and is only useful for the delegate usage and UI thread access part.

回答2:

I would use another thread for it:

labelWARNING.Visible = true;
labelWarningMessage.Text = "This module has a prerequisite module: " + item;
new Thread(() => {
    Thread.Sleep(5000);
    Dispatcher.BeginInvoke((Action)(() => { labelWARNING.Visible = false; }));
}).Start();

(this is for WPF, for WinForms should be essentially the same)

回答3:

I used a timer.

private void timer1_Tick(object sender, EventArgs e)
{        
      labelWarningMessage.Text = "";
      labelWARNING.Visible = false;
}

回答4:

Updated for async/await. This will

// Update all text with warning message
foreach (var x in mod)
{
      labelWARNING.Visible = true;
      labelWarningMessage.Text = "This module has a prerequisite module: " + x;
}

// Wait 1 second or 1000ms    
await Task.Delay(1000);

// Now dismiss the message
foreach (var x in mod)
      labelWarningMessage.Text = "";

The surrounding function needs to be an public async Task SomeMethod() or
public async void buttonClick(object sender, RoutedEventArgs e)
to use the await keyword

来源：https://stackoverflow.com/questions/9964555/how-can-i-update-the-value-of-a-label-control-periodically

标签

winforms

delay