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

From:
Robert Klemme <shortcutter@googlemail.com>
Newsgroups:
comp.lang.java.programmer
Date:
Sun, 12 Jun 2011 14:14:10 +0200
Message-ID:
<95josjFf62U1@mid.individual.net>
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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