Hi again Ravi,
as far as i got the initial problem, you want to sort the same data more than
once with different criteria, don't you?
With the TreeMap approach and any other sortable collection you can sort only
once with only one comparator by building a new Collection. You can't swap
comparators on the fly for resorting! So what are you going to do: You must have
a source collection because you don't want to ask db more than once. Then for
each sorting request you build a sorted destination collection, which you
immediatly throw away after you generated html.
Array.sort approach on the other hand can sort a given array of objects more
than once with different comparators and I suppose it sorts by moving objects
from one index to another without any superfluous object creation.
Peter
Ravi Shankar Jagarapu wrote:
> Kevin,
>
> Thanks a lot for gving me such useful pointers.
> Though aware of Lists and Comparators, I didn't know
> TreeMaps.
>
> From my original question of sorting, the data needs
> to be stored somewhere, right either in a file using
> TreeMaps or in the session.
>
> Performance wise which would be better?
>
> Thanks,
> Ravi.
>
> --- Kevin Baynes <[EMAIL PROTECTED]> wrote:
> > Ravi-
> >
> > You need to look at the Collections API for storing
> > your data. This will
> > teach you about TreeMaps, Lists and Comparators:
> >
> >
> http://developer.java.sun.com/developer/onlineTraining/collections/Collectio
> > n.html
> >
> http://developer.java.sun.com/developer/technicalArticles/Collections/Using/
> > index.html
> >
> > You will also need to understand Serialization and
> > the Serializable
> > interface:
> >
> >
> http://java.sun.com/docs/books/tutorial/essential/io/serializing.html
> >
> http://java.sun.com/products/jdk/1.2/docs/guide/serialization/
> > be sure to look at the examples and FAQ in the above
> > link.
> >
> > Kevin Baynes
> > SEAGULL Software
> >
> >
> >
> > > -----Original Message-----
> > > From: A mailing list for discussion about Sun
> > Microsystem's Java Servlet
> > > API Technology.
> > [mailto:[EMAIL PROTECTED]]On Behalf Of
> > Ravi
> > > Shankar Jagarapu
> > > Sent: Wednesday, July 18, 2001 11:01 PM
> > > To: [EMAIL PROTECTED]
> > > Subject: Re: Sorting using servlets
> > >
> > >
> > > Hi Mark,
> > >
> > > It would be great if you could give me an example
> > > code. I did not understand what you wrote? is
> > there
> > > any article where I could read about that?
> > >
> > > I don't know what is a TreeMap. Could you
> > enlighten
> > > me?
> > >
> > > Thanks,
> > > Ravi.
> > >
> > > --- Mark Galbreath <[EMAIL PROTECTED]> wrote:
> > > > Nah...that would not be efficient. Better to do
> > it
> > > > on the server by sending
> > > > the data into a TreeMap (implements SortedMap)
> > and
> > > > make it available to all
> > > > clients through a serialized download.
> > > >
> > > > Cheers!
> > > > Mark
> > > >
> > > > ----- Original Message -----
> > > > From: "Mike Peyvandi" <[EMAIL PROTECTED]>
> > > > Sent: Tuesday, July 17, 2001 11:39 PM
> > > >
> > > >
> > > > > Another option would be an applet in the
> > response
> > > > to take care of sorting
> > > > at
> > > > > the client side. This way you can omit some
> > extra
> > > > calls to the server for
> > > > > sorting purpose.
> > > > >
> > > > > Mike
> > > > >
> > > > >
> > > > > -----Original Message-----
> > > > > From: Kevin Baynes
> > > > > Sent: Tuesday, July 17, 2001 2:43 PM
> > > > >
> > > > > Ravi-
> > > > >
> > > > > You could make the database call, save the
> > results
> > > > into a temporary
> > > > > structure, put it where you can access it on
> > the
> > > > next call. You can do
> > > > this
> > > > > by either saving it to the Session, or by
> > > > serializing it to a file and
> > > > > accessing it by some key that you save to the
> > > > Session.
> > > > >
> > > > > You could use Arrays, Vectors, Lists, or a
> > custom
> > > > built object.
> > > > >
> > > > > I suggest you use Lists and Comparators for
> > > > storage and sorting.
> > > > >
> > > > > Kevin Baynes
> > > > > Seagull Software
> > > > >
> > > > > > -----Original Message-----
> > > > > > From: Ravi Shankar Jagarapu
> > > > > > Sent: Tuesday, July 17, 2001 12:39 PM
> > > > > >
> > > > > > I am retrieving data from the database with
> > > > several
> > > > > > fields, like for example first name, last
> > name,
> > > > > > join date, salary.
> > > > > >
> > > > > > This data is displayed by the servlet.
> > > > > > Now my requirement, is that, if anyone
> > clicks on
> > > > first
> > > > > > name, the data should now be displayed
> > sorted on
> > > > that
> > > > > > field and if on salary then sorted on
> > salary.
> > > > > >
> > > > > > I don't want to connect to the database each
> > > > time and
> > > > > > retrieve the same information just to sort
> > the
> > > > data
> > > > > > which is already available to me.
> > > > > >
> > > > > > Can anyone suggest a better method? Would be
> > > > great if
> > > > > > you could give an example code.
> > > > > >
> > > > > > Many Thanks,
> > > > > > Ravi.
> > > >
> > > >
> > >
> >
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