Some help with a sample SCWCD question based on Listeners.

[Abhijit Ghatnekar]

Hi All,

I'm very much confused by the following question and it's answer. It's a program actually.

Assume the below to be a valid HTTP Servlet that has been registered with a HTTPServletRequestAttribute Listener class.

public void doGet(HTTPServletRequest req, HTTPServletResponse res) throws ServletException, IOException {
   
     req.setAttribute("a","b");
     req.setAttribute("a","c");
     req.removeAttribute("a);
}

public void attributeAdded(ServletAttributeRequestEvent ev) {
    System.out.print("A"+ev.getName()+"=>"+ev.getValue());
}

public void attributeRemoved(ServletAttributeRequestEvent ev) {
    System.out.print("M"+ev.getName()+"=>"+ev.getValue());
}

public void attributeReplaced(ServletAttributeRequestEvent ev) {
    System.out.print("P"+ev.getName()+"=>"+ev.getValue());
}

And the output is this..

=======================
A:a->b P:a->b M:a->c
=====================

Now how is it that we get the old value of the attribute "a" even if we replace the value of the attribute a?
Is there a way, I could get the new, latest value of "a" the moment it is replaced? This could lead to a potential bug in a production code, not sure why it has to work like this.

Any thoughts?

Regds,
Abhijit.

[Roel De Nijs]

Please QuoteYourSources

[Ankur Gargg]

HI

You can use ev.getServletRequest().getAttribute("a") to get the new value thus the getValue() method has been coded to return the old value.


Regards
Ankur Garg