Groups | Search | Server Info | Login | Register

Groups > comp.lang.java.programmer > #5233

Re: Class.forName().newInstance() vs new

Show all headers | View raw

On 06/11/2011 08:04 PM, Patricia Shanahan wrote:
> On 6/11/2011 10:49 AM, Robert Klemme wrote:
>> On 11.06.2011 19:13, Abu Yahya wrote:
> ...
>>> else { // handle unrecognized
>>> Class<?> k = Class.forName(dbMgrClassName);
>>> db = (DB) k.newInstance();
>>> }
> ...
>> Doing if else cascades is certainly the worst thing - not so much
>> because of the performance but because of the deficiency that you need
>> to touch the code every time you want to add a new class. With the other
>> two approaches you do not have to do that.
> ...
>
> As coded, the forName code was left in as a fall-through handler, so it
> new classes can be handled without touching the code. Of course, that
> also means it has all the complications of both the if-else approach and
> the forName approach.

Thanks for hinting at this detail, Patricia!  Performance of this piece 
of code can vary dramatically with configured class / handler name. 
That adds a level of complication which might make tracking issues 
harder ("It was so fast in our lab, now on production it's awfully slow.").

Also I find the inconsistency about what needs to be configured 
irritating: the string can either be a logical name of a handler *or* a 
class name - and you cannot even distinguish them easily (handler names 
presented so far are also valid class names).  IMHO for this it would be 
better to have two different properties with clear defined precedence 
for logical handler name property.  That would also make it explicit 
that there are two mechanisms involved.  Even though, I still prefer one 
of the two uniform approaches (class name, factory class name).

Kind regards

	robert

Back to comp.lang.java.programmer | Previous | Next — Previous in thread | Next in thread | Find similar

Thread

Class.forName().newInstance() vs new Abu Yahya <abu_yahya@invalid.com> - 2011-06-11 22:43 +0530
  Re: Class.forName().newInstance() vs new David Lamb <dalamb@cs.queensu.ca> - 2011-06-11 13:46 -0400
  Re: Class.forName().newInstance() vs new Robert Klemme <shortcutter@googlemail.com> - 2011-06-11 19:49 +0200
    Re: Class.forName().newInstance() vs new Patricia Shanahan <pats@acm.org> - 2011-06-11 11:04 -0700
      Re: Class.forName().newInstance() vs new Abu Yahya <abu_yahya@invalid.com> - 2011-06-11 23:52 +0530
      Re: Class.forName().newInstance() vs new Robert Klemme <shortcutter@googlemail.com> - 2011-06-12 14:05 +0200
        Re: Class.forName().newInstance() vs new Patricia Shanahan <pats@acm.org> - 2011-06-12 07:10 -0700
          Re: Class.forName().newInstance() vs new Martin Gregorie <martin@address-in-sig.invalid> - 2011-06-12 14:37 +0000
            Re: Class.forName().newInstance() vs new Robert Klemme <shortcutter@googlemail.com> - 2011-06-12 18:17 +0200
              Re: Class.forName().newInstance() vs new Joshua Cranmer <Pidgeot18@verizon.invalid> - 2011-06-12 15:25 -0400
            Re: Class.forName().newInstance() vs new lewbloch <lewbloch@gmail.com> - 2011-06-15 06:58 -0700
              Re: Class.forName().newInstance() vs new Nigel Wade <nmw-news@ion.le.ac.uk> - 2011-06-16 10:16 +0100
          Re: Class.forName().newInstance() vs new Robert Klemme <shortcutter@googlemail.com> - 2011-06-12 18:10 +0200
    Re: Class.forName().newInstance() vs new Abu Yahya <abu_yahya@invalid.com> - 2011-06-11 23:53 +0530
      Re: Class.forName().newInstance() vs new "John B. Matthews" <nospam@nospam.invalid> - 2011-06-11 15:43 -0400
        Re: Class.forName().newInstance() vs new "John B. Matthews" <nospam@nospam.invalid> - 2011-06-11 15:50 -0400
          Re: Class.forName().newInstance() vs new lewbloch <lewbloch@gmail.com> - 2011-06-15 06:49 -0700
            Re: Class.forName().newInstance() vs new Michael Wojcik <mwojcik@newsguy.com> - 2011-06-16 11:21 -0400
              Re: Class.forName().newInstance() vs new lewbloch <lewbloch@gmail.com> - 2011-06-17 06:45 -0700
                Re: Class.forName().newInstance() vs new Michael Wojcik <mwojcik@newsguy.com> - 2011-06-17 12:29 -0400
                Re: Class.forName().newInstance() vs new Lewis Bloch <lewisbloch@google.com> - 2011-06-17 11:07 -0700
                Re: Class.forName().newInstance() vs new "John B. Matthews" <nospam@nospam.invalid> - 2011-06-18 02:01 -0400
                Re: Class.forName().newInstance() vs new Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2011-06-18 10:19 -0300
                Re: Class.forName().newInstance() vs new Robert Klemme <shortcutter@googlemail.com> - 2011-06-18 20:16 +0200
                OT language stuff (was Re: Class.forName().newInstance() vs new) blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-06-20 19:19 +0000
                Re: OT language stuff (was Re: Class.forName().newInstance() vs new) Martin Gregorie <martin@address-in-sig.invalid> - 2011-06-20 20:46 +0000
                Re: OT language stuff (was Re: Class.forName().newInstance() vs new) blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-06-21 20:42 +0000
                Re: OT language stuff (was Re: Class.forName().newInstance() vs new) Gene Wirchenko <genew@ocis.net> - 2011-06-21 14:22 -0700
                Re: OT language stuff (was Re: Class.forName().newInstance() vs new) Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2011-06-20 18:55 -0300
                Re: OT language stuff (was Re: Class.forName().newInstance() vs new) Tom Anderson <twic@urchin.earth.li> - 2011-06-21 23:29 +0100
                Re: OT language stuff (was Re: Class.forName().newInstance() vs new) Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2011-06-21 20:39 -0300
                Re: OT language stuff (was Re: Class.forName().newInstance() vs new) "John B. Matthews" <nospam@nospam.invalid> - 2011-06-21 23:00 -0400
                Re: OT language stuff (was Re: Class.forName().newInstance() vs new) Tom Anderson <twic@urchin.earth.li> - 2011-06-22 20:02 +0100
                Re: OT language stuff (was Re: Class.forName().newInstance() vs new) blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-06-22 20:03 +0000
                Re: OT language stuff (was Re: Class.forName().newInstance() vs new) Michael Wojcik <mwojcik@newsguy.com> - 2011-06-23 12:04 -0400
                Re: OT language stuff (was Re: Class.forName().newInstance() vs new) Michael Wojcik <mwojcik@newsguy.com> - 2011-06-23 11:58 -0400
                Re: Class.forName().newInstance() vs new Gene Wirchenko <genew@ocis.net> - 2011-06-20 14:01 -0700
                Re: Class.forName().newInstance() vs new Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2011-06-20 18:53 -0300
                Re: Class.forName().newInstance() vs new Michael Wojcik <mwojcik@newsguy.com> - 2011-06-21 19:53 -0400
                Re: Class.forName().newInstance() vs new blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-06-22 20:01 +0000
                Re: Class.forName().newInstance() vs new Michael Wojcik <mwojcik@newsguy.com> - 2011-06-23 12:16 -0400
                OT language stuff (was Re: Class.forName().newInstance() vs new) blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-06-20 19:18 +0000
                Re: OT language stuff (was Re: Class.forName().newInstance() vs new) Martin Gregorie <martin@address-in-sig.invalid> - 2011-06-20 20:52 +0000
        Re: Class.forName().newInstance() vs new Robert Klemme <shortcutter@googlemail.com> - 2011-06-12 14:14 +0200
  Re: Class.forName().newInstance() vs new Patricia Shanahan <pats@acm.org> - 2011-06-11 11:01 -0700
  Re: Class.forName().newInstance() vs new Roedy Green <see_website@mindprod.com.invalid> - 2011-06-13 06:16 -0700
  Re: Class.forName().newInstance() vs new Ian Shef <invalid@avoiding.spam> - 2011-06-14 20:07 +0000

csiph-web