Ravi,
How much data are you talking about here? Using either a file or the
session to store the data is not a very good idea. Using a file limits the
scaleability and would be relatively slow. Maintenance of the temporary
files also becomes an issue. Use of files is also problematic if server
clusters are used b/c it ties the session to a particular machine. Large
amounts of data should not be stored in the user's session either b/c it
limits the scaleability again and eats up the server's memory.
For a large # of records, I'd recommend just connecting to the database
again and use the database to sort for you using the ORDER BY clause. The
database is highly optimized for this purpose. An EJB is a great solution
if you can use them.
Regards,
Richard
At 10:14 AM 7/19/01 -0700, you 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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