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

From	Robert Klemme <shortcutter@googlemail.com>
Newsgroups	comp.lang.java.programmer
Subject	Re: Class.forName().newInstance() vs new
Date	2011-06-12 14:14 +0200
Message-ID	<95josjFf62U1@mid.individual.net> (permalink)
References	<it07on$ilc$1@speranza.aioe.org> <95ho4qFd7cU1@mid.individual.net> <it0brg$s3t$2@speranza.aioe.org> <nospam-BA6E1B.15432711062011@news.aioe.org>

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On 06/11/2011 09:43 PM, John B. Matthews wrote:
> In article<it0brg$s3t$2@speranza.aioe.org>,
>   Abu Yahya<abu_yahya@invalid.com>  wrote:
>
>> Could you give an example of how the factory method might look like?
>
> There's some good examples here:
>
> <http://en.wikipedia.org/wiki/Factory_method_pattern>
>
> And in the linked article, "Item 1: Consider static factory methods
> instead of constructors."
>
> <http://drdobbs.com/java/208403883?pgno=1>

If Class.forName() is the bottleneck then a static factory method does 
not help in this particular case.  You would have to configure the 
method name or a class name anyway and use reflection to get at the 
instance or method.

Abu, to answer your question (pseudo code):

interface com.your.company.db.DbManager {
  // methods
}

interface com.your.company.db.DbManagerFactory {
   DbManager create(/* args if needed */) throws WhateverException
}

class com.your.company.db.ora.OraDbManager implements DbManager {
   // ...
}

class com.your.company.db.ora.OracleDbManagerFactory implements 
DbManagerFactory {
   public DbManager create() {
     return new OraDbManager();
   }
}


Kind regards

	robert

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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

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