Solved

Factory Design Pattern Template

Posted on 2012-04-02
3
280 Views
Last Modified: 2012-08-14
I came across the following code

public class MessageSupportFactory
{
    private static MessageSupportFactory instance = null;

    private MessageSupportFactory()
    {
     .....
    }

   static { 
         instance = new MessageSupportFactory(); 
         }

   public static MessageSupportFactory getInstance()
   {
      return instance;
   }

.....
}

Open in new window



The question is when should we use a template like this and what does it accomplish?
Thank you.
0
Comment
Question by:skiabox
  • 2
3 Comments
 
LVL 12

Assisted Solution

by:Sharon Seth
Sharon Seth earned 333 total points
ID: 37799813
The code(template) in MessageSupportFactory class is more about singleton pattern . Singleton pattern is where you want a single instance of the class . The constructor is made private here , so that clients cannot instantiate it .The only way to get an instance of this class is the getInstance() method.  Singletons are used mostly for resources like connectionfactories , applicationcontexts etc.
0
 
LVL 12

Assisted Solution

by:Sharon Seth
Sharon Seth earned 333 total points
ID: 37799861
If you are looking for the Factory design pattern -  As its name implies classes implementing this pattern act as factories that produce instances . Suppose you want to get a connection object to an underlying database . Instead of directly using the new operator and instantiating the connection object , you would approach the factory class (say , ConnectionFactory) to give you an instance of the connection object.

The advantage of using factory pattern . Tomorrow , if you move to a different database vendor , you need not change client code to implement connection logic for that specific vendor . Instead , the connectionFactory (which would have been coded to return specific instances for specific DB vendors) , would handle that

So , in simpler terms , this pattern  creates an abstraction over how classes(in our example , connections) are created
0
 
LVL 37

Accepted Solution

by:
zzynx earned 167 total points
ID: 37800281
0

Featured Post

Is Your Active Directory as Secure as You Think?

More than 75% of all records are compromised because of the loss or theft of a privileged credential. Experts have been exploring Active Directory infrastructure to identify key threats and establish best practices for keeping data safe. Attend this month’s webinar to learn more.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
What is JNDI datasource in spring 1 50
Java Timer (static) 9 36
servlet doXXX methods 3 31
servlet example issue 6 27
Are you developing a Java application and want to create Excel Spreadsheets? You have come to the right place, this article will describe how you can create Excel Spreadsheets from a Java Application. For the purposes of this article, I will be u…
Introduction This article is the second of three articles that explain why and how the Experts Exchange QA Team does test automation for our web site. This article covers the basic installation and configuration of the test automation tools used by…
Viewers will learn about basic arrays, how to declare them, and how to use them. Introduction and definition: Declare an array and cover the syntax of declaring them: Initialize every index in the created array: Example/Features of a basic arr…
Viewers will learn about the regular for loop in Java and how to use it. Definition: Break the for loop down into 3 parts: Syntax when using for loops: Example using a for loop:

947 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

16 Experts available now in Live!

Get 1:1 Help Now