interfce and implementation of method

[psachin joshi]

we use getParameter() and other methods of httpServletRequest interface but we dont implement it so i want to know where and who implement these methods.
also we make httpServletRequest object pass in doget method to call these methods how it is possible to make an object of an interface.

[Amol Nayak]

It is implemented by vendor whose container you are using, it is the container's responsibility to pass an appropriate instance of the classes implementing the ServletRequest and ServletResponse interfaces to service method.

[sudhir nim]

It is the servlet container who implements this interface.
Whenever there is a request to a servlet or jsp, servlet container parses the incoming request, prepares a request object and passes it to service method.

[Stan James]

Hey, welcome to the ranch, psachin joshi!

If you start looking you'll see you do this kind of thing all the time. Say you write a method:

public void myMethod( List input )
{
   Iterator it = list.iterator();
   while( it.hasNext() )
   {
       etc.
   }
}

When somebody calls that method, you don't know what kind of List they will pass. It might be a familiar one from the Java library, or some totally new List implementation they made up. That's the goodness of abstraction: you can ignore the parts you don't need to know about and focus on the parts you do need. For example, you know the List will give you an Iterator but you don't have to know how it works.

[paritosh ranjan]

It really makes the task easy as you don't need to explore the request object to get the parameter you need.