On Fri, May 25, 2001 at 09:01:51AM -0400, Leon Palermo wrote:
> Re: problems installing tomcat on linuxHello All,
>
> Let me preface this email by saying that I only put 'EXPERTS ONLY' so you hot shot
>programmers would actually read this email. If you are reading this, it worked!
>
> I have an odd problem that I was hoping someone could help with.
>
> I have a servlet that all jsps in the system are dispatched from. I create a bean
>in this servlet and add it to the request object like so...
>
> com.blah.blah.MyBean abean = (com.blah.blah.MyBean)
>Beans.instantiate(this.getClass().getClassLoader(),"com.blah.blah.MyBean");
> ...
> request.setAttribute("thename", abean);
>
> I have also tried this to create the bean....
>
> com.blah.blah.MyBean abean = new com.blah.blah.MyBean();
>
>
> and also tried to place the object in the request like so....
>
> pageContext.setAttribute("thename", abean, PageContext.REQUEST_SCOPE);
>
> Anywho, I then have the following in my jsp page...
>
> <jsp:useBean id="thename" scope="request" class="com.blah.blah.MyBean" />
>
> I get a java.lang.ClassCastException from the jsp. So, I decided to do a little
>error hunting in a jsp using the following code...
>
> <%try{
> System.out.println(request.getAttribute("thename") == null);
> System.out.println(request.getAttribute("thename") instanceof
>com.blah.blah.MyBean);
> System.out.println(request.getAttribute("thename").getClass().getName());
>
>System.out.println(zedak.docworx.jspsupport.beans.BrandBean)request.getAttribute("thename"));
> }catch (ClassCastException e){
> System.out.println("CLASS CAST EXCEPTION!");
> }
> %>
>
> The results of the code is as follows:
>
> false
> false
> com.blah.blah.MyBean
> CLASS CAST EXCEPTION!
>
> So, the attribute is present in the request object, it is not an instance of
>'com.blah.blah.MyBean'; but the object's class name is 'com.blah.blah.MyBean'. Does
>anyone have an idea what is going on? How can the object's class name be
>'com.blah.blah.MyBean' but not be able to cast to 'com.blah.blah.MyBean'?
>
> Thanks in advance!
>
> Leon Palermo
I'm pretty sure you've got a precedence problem.
this code:
(com.blah.blah.MyBean)request.getAttribute("whatever");
will try to cast request to com.blah.blah.MyBean and then apply the
getAttribute generic function to that (this had better NOT work :).
try this:
(com.blah.blah.MyBean)(request.getAttribute("whatever"));
http://java.sun.com/docs/books/jls/index.html You want section 15.7,
Evaluation order.
hope this helps.
--
-Marco
Ring the bells that still can ring.
Forget the perfect offering.
There's a crack in everything.
It's how the light gets in.
-Isonard Cohen
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