Comments on: A Spring Singleton is not a Singleton

By: Spring singleton created multiple times

Spring singleton created multiple times — Thu, 27 Oct 2011 20:25:57 +0000

[...] have read: http://www.digizenstudio.com/blog/2006/09/14/a-spring-singleton-is-not-a-singleton/ but I don’t think I am dealing with the same class defined twice with two different bean [...]

By: hansi

hansi — Wed, 19 Oct 2011 13:48:42 +0000

hey!

yes, a very old post and still interresting. just so i get this right, is there any noticeable difference to this plain java variant:

class Foo{
… instance methods …
}

class MyApplicationThings{
public final static FOO1 = new Foo();
public final static FOO2 = new Foo();
}

is there any functional difference?
(and please don’t get into an argument about aesthetics, a library-less solution with fewer lines of code simply wins).

(p.s. i’m putting aside the fact here that i’ve never ever had the need for having multiple instances of a singleton; and another note to that note: having multiple singletons makes my oxymoron-alarm go off, loudly).

By: Ramya

Ramya — Thu, 18 Aug 2011 11:01:16 +0000

I am wondering about the example above. The foo1 and foo2 create 2 instances. Does that really work? If so, then doesnt the whole concept of the ’singleton’ in spring terms become invalid?

By: Deepesh

Deepesh — Fri, 03 Jun 2011 11:51:08 +0000

Five year old post but still useful.

By: Paul

Paul — Fri, 12 Nov 2010 07:19:39 +0000

here is a best differentiation of the singleton vs. the prototype scopes of Spring Framework

http://www.adobocode.com/spring/springs-scopes-singleton-vs-prototype

By: lwpro2

lwpro2 — Fri, 01 Oct 2010 06:16:55 +0000

They are two different implementations. Spring is using bean factory load instance from start up, then cache it; which behaves as single instance for all. Strict singleton pattern is static class variable, and never the instance can be publicly created.

By: Sravan

Sravan — Mon, 27 Sep 2010 14:26:16 +0000

Thanks Jing.
Thats a very useful article.
One question.
When a bean is singleton for “Spring IoC container”, the entire application will have access to only the same SINGLE instance of the bean(as most applications contain only one ApplicationContext).
So, what is the advantage we see here by making all of our beans Singleton (other than configuring) ? (as, for our application its still a Singleton, can see just like a class loader singleton) ?

By: Anonymous

Anonymous — Tue, 31 Aug 2010 13:35:12 +0000

good~ thanks!

By: Amal

Amal — Mon, 11 Jan 2010 02:26:43 +0000

Very well explained. Always wondered about the fine differences between the two. Thanks for the explanation!

By: JEx

JEx — Fri, 30 Oct 2009 08:03:11 +0000

Perfectly nice One!!!

By: Thamayanthi

Thamayanthi — Thu, 25 Jun 2009 12:22:43 +0000

Nice Explanation!!!

By: shan

shan — Mon, 22 Jun 2009 05:27:39 +0000

I it very nice explanation. So you are gonna say Spring developers have to take a special consideration in this regard.

By: jaa

jaa — Tue, 09 Jun 2009 05:49:32 +0000

In this context, it’s also useful to note that by default Spring beans are singleton – i.e even if you don’t specify singleton=”true” or scope=”singleton”, it’s created as a Spring-Singleton. So, there are certain cases where we need to explicitly say scope=”prototype” to avoid multithreaded issues.

By: Pawan

Pawan — Thu, 16 Apr 2009 19:44:00 +0000

Very Nicely Explained !

By: Parag Soman

Parag Soman — Thu, 28 Aug 2008 20:57:05 +0000

Thanks a lot for this article and removing my confusion.

By: Raish

Raish — Fri, 04 Apr 2008 13:59:37 +0000

Good explanation, thnk!

By: pwu

pwu — Wed, 12 Sep 2007 20:42:13 +0000

very well explained! thanx

By: freizl

freizl — Fri, 22 Sep 2006 09:03:15 +0000

good article about this confusion!
and there is a section in the RD J Chapter 4,’Avoid a Proliferation of Singletons by Using an Application Registry’, seem to also talk about this issue.