Attributes Doubt??

[Joe Harry]

Hi Guys,

I'm not able to understand the following question from the HFSJ book!,

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

public void attributeAdded(ServletRequestAttributeEvent ev){
System.out.println("A:" + ev.getName() + "->" + ev.getValue());
}

public void attributeAdded(ServletRequestAttributeEvent ev){
System.out.println("M:" + ev.getName() + "->" + ev.getValue());
}

public void attributeAdded(ServletRequestAttributeEvent ev){
System.out.println("P:" + ev.getName() + "->" + ev.getValue());
}

How will this print A:a->b P:a->b M:a->c??

Please help me guys??

Thanks in advance!

[Micheal John]

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

public void attributeAdded(ServletRequestAttributeEvent ev){
System.out.println("A:" + ev.getName() + "->" + ev.getValue());
}

public void attributeAdded(ServletRequestAttributeEvent ev){
System.out.println("M:" + ev.getName() + "->" + ev.getValue());
}

public void attributeAdded(ServletRequestAttributeEvent ev){
System.out.println("P:" + ev.getName() + "->" + ev.getValue());
}

How will this print A:a->b P:a->b M:a->c??

If your are taking from HFSJ, then It should be like this:

public void doGet(HttpServletRequest req, HttpServletResponse res) throws IOException, ServletException{
req.setAttribute("a", "b");
req.setAttribute("a", "c");
req.removeAttribute("a");
}
 
public void attributeAdded(ServletRequestAttributeEvent ev){
System.out.println("A:" + ev.getName() + "->" + ev.getValue());
}
 
public void attributeRemoved(ServletRequestAttributeEvent ev){
System.out.println("M:" + ev.getName() + "->" + ev.getValue());
}
 
public void attributeReplaced(ServletRequestAttributeEvent ev){
System.out.println("P:" + ev.getName() + "->" + ev.getValue());
}
 
How will this print A:a->b P:a->b M:a->c??
 

NO surprise in the o/p:
First your adding the attribute so A:a->b
Then your replacing the value for the same attribute "a", so P:a->b
Finally removing..

I think the problem for you is with P:a->b instead of P:a->c..the getValue() method returns the old value of the attribute if the attribute was replaced
[ January 06, 2007: Message edited by: Micheal John ]

[Joe Harry]

Michael,

Thanks for the help, I was dubious about the way attributes work with respect to the above question. Could you tell me where I can find a suitable explanation for the question given on that page in the HFSJ book??