Actionform auto population

When a property on ActionForm matches a request parameter, struts framework automatically sets the property to the value of the request paramter. How does this auto population happen ? I would like to know what happens in the background.

Struts is an open-source project--have you considered just reading the code?

If you were going to implement that kind of functionality, how do you think you might go about doing it? For instance, when I think of a simple example, letting processing a form with a "firstName" element, I'd start by thinking about what's in the request parameters: a parameter named "firstName". If I wanted to initialize an instance property, my first assumption would be that I'd look for a setter named "setFirstName()" that takes a String.

There are more details than that, but you get the idea. Plus you have access to the source code--use it!

Ok ,thanks for your response... I got to know that there is something called as Reflection that's used which is responsible for the autopopulation.

Where all do we use Reflection concept in java ?

Any good websites that you can point me to ?

Thanks.

http://java.sun.com/docs/books/tutorial/reflect/

There's a whole book written about reflection (Java Reflection in Action). It's used all over the place, for a myriad of reasons.