Actually, I wanted to pass this list from within a Tag to be used inside
another Servlet class, (i.e. the tag class after finishing rendering its
elements, goes to a servlet, so, i need to pass this list to that servlet.
As i have stated above, i used the following to store the list in the
request object:
[code]pageContext.getRequest().setAttribute("QList", list);[/code]
In the servlet, i used the following to retrive the list:
List<Integer> list = (List<Integer>)request.getAttribute(
"QList");
I tried to access the above list by a small code snippet that prints its
size:
[code]out.println( list.size() );[/code]
But i got an exception stating that a NullPointerException has occured at
the size printing statement. That's mean, i think, the list didn't stored
correctly in the request object, am I true?
On 7/23/07, David Smith <[EMAIL PROTECTED]> wrote:
Typical design is servlet forwarding to jsp for view. Tags being jsp
elements occur after servlets have executed. So you can see how your
problem is a little curious in that jsps don't typically forward to
servlets. If you are forwarding a request from jsp to servlet, let us
know.
However if you are storing a object in a request during jsp execution
intending it to be available to the servlet on the next request, that
doesn't work. The request is cleared and recycled when jsps finish
writing to the client. When a new request comes in, the request
attribute list is empty. If you need this list to live between
requests, you need to place it in the session.
--David
Mohammed Zabin wrote:
> Thank you Johnny,
> To be specific this is my question
> Hi all
>
> I am trying to pass an object from a tag to a servlet. i did the
> following,
>
> 1. In the tag class, i put:
>
> pageContext.getRequest().setAttribute("QList", list);
>
>
>
> The above Tag will go to a servlet, i need to read the above request
> attribute in the servlet, how can i do this?, i tried
>
> List<Integer> list = (List<Integer>)request.getAttribute("QList");
>
> , but when i tried to access the read list, it gave me
> NullPointerException...What do u think?
>
>
> On 7/23/07, Johnny Kewl <[EMAIL PROTECTED]> wrote:
>
>>
>> Hi Mohammed,
>> Cant say I really understand the question....
>>
>> In general this is what the Session Objects are for....
>> So say you have a servlet and a JSP page.... and say the servlet
>> makes the
>> bean with the Array List in it.... then if you
>>
>> session.setAttribute("MyBean", MyBean);
>>
>> you can get it (MyBean) back when the next call comes into say the JSP
>> page....
>>
>> Now if you read up on this you will see you can also set 'request'
>> objects.... and these are good for when you say dispatch a request to a
>> JSP
>> page from the servlet and want to pass a bean across.
>>
>> Anyway... if you just google for "servlet session and
setAttribute"....
>> you
>> will be on your way... I think ;)
>> This area of servlet programming is one of the things that make it
>> such a
>> powerful technology.
>> Have fun...
>>
>> ----- Original Message -----
>> From: "Mohammed Zabin" <[EMAIL PROTECTED]>
>> To: "Tomcat Users List" <users@tomcat.apache.org>
>> Sent: Monday, July 23, 2007 11:18 AM
>> Subject: Bean and Servlet
>>
>>
>> > Hi All
>> > What is the best way to pass a list collection from a Bean to a
>> Servlet?
>> > Thank you
>> >
>>
>>
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>
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