If I change private to public,will it act same?
Thanks,
chris
Bo Xu wrote:
> Rajesh Kumar wrote:
>
> > Hello all,
> > Please go through this code to understand the problem
> >
> > public class testServlet extends HttpServlet{
> >
> > private String UserName=null;
> >
> > public void init()....{
> > ...}
> > public void doPost(..)..{
> > {
> > PrintWriter out=res.getWriter();
> > out.println("First:"+UserName);
> > ..
> > ..
> > UserName="somevalue";
> > out.println("Second:"+UserName);
> > }
> > }
> >
> > When I run this Servlet ,output->First: null Second:somevalue
> > Run this Servlet in another browser(second time), I got the output as ,
> > First:somevalue Second:somevalue.
> > How the old value is retained.Each time the servlet is called,it is
> > initiated and so the First value should be null.
> > Kindly let me know the reason for this behaviour.
> >
> > This I avoided by declaring the UserName inside the doPost method.
> >
> > Thanks,
> > Rajesh
>
> [...]
>
> Hi :-) I am not sure, but from Servlet spec2.2 and several emails from
> Servelt-List:
>
> # UserName is a private instance field in your Servlet class, so the line
> *private String UserName=null;* will only work when Servlet container makes
>
> a new instance of your Servlet class.
>
> # if we have n Servlet definitions, then normally, we will have n instances of
> our
> Servlet class. Servlet container will use these instances to make threads
> for
> client accessing, and after this client accessing has been responsed,
> normally
> this instance will not be *destroyed* -> it can be used in next time. so
> now your
> UserName is also there, and still refrences to a String whose value is
> "somevalue"
>
> # Servlet container will make a new thread from one of these instances for
> every
> client accessing, if it happens that the two threads for your two client
> accessings
> are from the same instance, then perhaps we will get the result mentioned in
> your
> email. hope my guessing is right :-)
>
> Bo
> Dec.01, 2000
>
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