Eventhandler is fired more than once - events

Question

I have a problem with two of my EventHandlers, they work the same, so here is one:
private void Form1_Load(object sender, EventArgs e)
{
webBrowserWebsite.Url = new System.Uri(textBoxURL.Text, System.UriKind.Absolute);
webBrowserWebsite.DocumentCompleted += new WebBrowserDocumentCompletedEventHandler(webBrowserWebsite_DocumentCompleted);
}
void webBrowserWebsite_DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e)
{
StreamWriter(Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData) + #"\CurrentData.wfd");
sw.Write(webBrowserWebsite.Document.Body.InnerText);
sw.Close();
}
The problem is, that the EventHandler fires multiple times, it doesn't stop!
Why is it doing this?
Thanks in advance

Answer 1

The code that you have written won't compile (your StreamWriter in your EventHandler isn't assigned to anything) and without more context as to how you are calling this, it is difficult to say for certain.
But the most likely reason is you are calling Form1_Load multiple times, but using the same webBrowserWebsite object. Each time the form loads, you are adding a new Event Handler. And since you aren't showing any code showing where you removing the event handler, I'm guessing it fires once for each time you call Form_Load.
Depending on your design, you are better off adding the event handler in the constructor so it is only added once regardless of the number of times you load the form.
public Form1()
{
webBrowserWebsite.DocumentCompleted += new WebBrowserDocumentCompletedEventHandler(webBrowserWebsite_DocumentCompleted);
}
private void Form1_Load(object sender, EventArgs e)
{
webBrowserWebsite.Url = new System.Uri(textBoxURL.Text, System.UriKind.Absolute);
}
Or remove the event handler in the event handler:
void webBrowserWebsite_DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e)
{
StreamWriter(Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData) + #"\CurrentData.wfd");
sw.Write(webBrowserWebsite.Document.Body.InnerText);
sw.Close();
webBrowserWebsite.DocumentCompleted -= webBrowserWebsite_DocumentCompleted;
}
Also, since StreamWriter implements IDisposible, you should be putting it inside of a using block or at least calling sw.Dispose() at the end of the method