calling sub class' method from super class

[ankur rathi]

Hi,

This line is with reference to page 294 of HFS&J.

"Builds the service() method. This service method's actual name is _jspService(). It's called by the servlet superclass' overridden service() method....."

So in case of tomcat, the super class of this servlet (which was JSP before) is HttpJspBase. This HttpJspBase is also servlet (extends HttpServlet) and has overriding service() method. Now this overriding service() method calls our _jspService() method...

I am confused, how can we call sub class' method from super class without even knowing the name of sub class???

Hope my question is clear.
Thanks.

[ May 16, 2006: Message edited by: rathi ji ]

[Christophe Verré]

Because HttpJspBase defines the _jspService method as abstract.

for example:

class HttpJspBase extends HttpServlet {
  ...
  public final void service(...) {
     _jspService(...);
  }
 
  public abstract void _jspService(...);
}
 
class MyJspFile extends HttpJspBase {
  public void _jspService(...) {
  }
}

The container is going to instanciate your jsp with something like:
HttpJspBase servlet = new MyJspFile();

I hope this is clear enough.

[Ben Souther]

It says:

from the superclass' overridden service() method

[ankur rathi]

Thanks Ben and Satou.
I got the point Ben.

[ May 16, 2006: Message edited by: rathi ji ]