How can add Event Handlers to controls in ASP.NET 2.0?
Most of the code in an ASP.NET web page is placed inside event handlers that react to web control
events. Using Visual Studio, you can add an event handler to your code in three ways:
Type it in by hand: In this case, you add the method directly to the page class. You must specify
the appropriate parameters so that the signature of the event handler exactly matches the signature
of the event you want to handle. Youll also need to edit the control tag so that it links
the control to the appropriate event handler. (Alternatively, you can use delegates to wire this
up programmatically.)
Double-click a control in design view: In this case, Visual Studio will create an event handler
for that controls default event (and adjust the control tag accordingly). For example, if you
double-click the page, it will create a Page.Load event handler. If you double-click a Button
control, Visual Studio will create an event handler for the Click event.
Choose the event from the Properties window: Just select the control, and click the lightning
bolt in the Properties window. Youll see a list of all the events provided by that control. Doubleclick
in the box next to the event you want to handle, and Visual Studio will automatically
generate the event handler in your page class and adjust the control tag.
The second and third options are the most convenient. The third option is the most flexible,
because it allows you to select a method in the page class that youve already created. Just select the
event in the Properties window, and click the drop-down arrow at the right. Youll see a list that
includes all the methods in your class that match the signature this event requires. You can then
choose a method from the list to connect it. The only limitation of this technique
is that it works exclusively with web controls, not server-side HTML controls.