Question

I am confused with the concept interface in Servlet. I want to make sure i understand what i am working on. So any explanations will be much appreciated.

public class Testing implements Servlet 
{
    public void init(ServletConfig arg0) throws ServletException
   {
       /* getting some values from web.xml } */
   }

}

(i) init will be called by tomcat
(ii) ServletConfig is an interaface, How can an interface object can be created ?

Answer 1

arg0 might be a reference of ServletConfig but it is pointing to an object of class implementing ServletConfig..

Eg: –

public interface A {
}

public class B implements A {
}

public class C {
    public static void main(String args[]) {
        A obj = new B();
    }
}

Assume here that interface A is ServletConfig, and class B is the class implementing ServletConfig.. Now you can pass obj which is of type A and point to object of class B, to any method..