Todd Mytkowicz wrote:
> Hello Tyler,
>
> I am glad you brought up the Collections point. I am using a Hashtable as
> an instance variable in my servlet. That Hashtable is itself synchronized.
> (Implemented inside the Hashtable class). I am guessing that because of the
> Hashtable being synchronized I should not have to worry about synchronizing
> access to it. Could you back me up?
>
The synchronization inside Hashtable means that you don't have to worry about
having two threads do a get() or put() or remove() at the same time and
corrupting the internal state of the Hashtable itself. The objects that you
retrieve from the Hashtable may have their own thread-related issues, however,
because they can now be accessed simultaneously by two threads that do a get()
on the same key.
>
> I am not using the session object because we are using JSDK2.0 and that
> object did not exist with that release. ( Upgrade is in the near future...I
> hope :) )
>
Don't tell that to all the Apache JServ application developers who are happily
using sessions! :-)
HttpSession has been around a long time -- including in JSDK 2.0. Other things
(such as request dispatchers) were added in 2.1, but sessions are there. In the
2.0 servlet API, you use HttpSession.getValue(), HttpSession.putValue(), and
HttpSession.removeValue() to manipulate user attributes of the session.
>
> Any other suggestions out there for using a non static global variable???
>
> -Todd
>
Craig McClanahan
>
> >From: TKV Tyler VanGorder <[EMAIL PROTECTED]>
> >Reply-To: "A mailing list for discussion about Sun Microsystem's Java
> > Servlet API Technology." <[EMAIL PROTECTED]>
> >To: [EMAIL PROTECTED]
> >Subject: Re: Non static global variables
> >Date: Thu, 6 Jul 2000 13:32:23 -0700
> >
> >Hi Todd,
> >
> >Only one instance of the servlet will be created and it will service
> >multiple client requests. So if client 'A' changes the variable to true,
> >then Client 'B' will see that. Also note, that since it is a boolean value
> >you do not need to synchronize your variable because the assignment of the
> >boolean is atomic. If you
> >were using something like a hash map or other collection, you would need to
> >synchronize around access to that instance variable because multiple
> >threads
> >of execution could be accessing it concurrently.
> >
> >If you want the variable to be on a "per-user" basis you will need to store
> >that variable in the Session object for each user.
> >
> >
> >Tyler Van Gorder
> >[EMAIL PROTECTED]
> >
> >
> >
> >
> > > -----Original Message-----
> > > From: Todd Mytkowicz [mailto:[EMAIL PROTECTED]]
> > > Sent: Thursday, July 06, 2000 1:08 PM
> > > To: [EMAIL PROTECTED]
> > > Subject: Non static global variables
> > >
> > >
> > > Hello all,
> > >
> > > In my servlet, I create an instance variable as such...
> > >
> > > private boolean temp = false;
> > >
> > > ...
> > >
> > > An instance of this servlet is created the first time the
> > > servlet is called.
> > > My understanding is that this variable is only initialized
> > > that first time.
> > >
> > > Is this temp variable implicitly static? ie, if one user changes the
> > > variable, will other servlets see that change?
> > >
> > > In more general terms, I want this variable to act as a
> > > global variable with
> > > a seperate value to each request.
> > >
> > > If user A requests my servlet and changes the temp to true,
> > > will subsequent
> > > users see a value of true?
> > >
> > > Thanks for the help.
> > >
> > > Todd Mytkowicz:
> > > [EMAIL PROTECTED]
> > > ______________________________________________________________
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