Real World Example of Singleton Pattern

[Vineela Devi]

Hi,

Can anyone please give me a real world example of using singleton pattern.

Regards,
Vineela

[Vinny Menon]

Hi Vineela,
one real world example would be:
in one of my earlier projects,we had used the business delegate design pattern.i.e.
we had used struts framework and within the action class ,we made call to the business delegate classand from the business delegate class we made the call to the session bean.


we didnt want multiple instances of the business delegate and wanted to control the instance of the Business Delegate.hence we made it a singleton
class.

the flow is like this..

Jsp-->action class-->Business Delegate(Singleton)-->Session Beans-->entity bean-->Database.



hth
cheers
vinny m

[Reid M. Pinchback]

Many services in a J2EE server are arguably instances of the singleton pattern. At any one time only one variation of a specific service will be in use by the server, but different configurations of the server will allow different choices of service. For example, there will only be one global JNDI tree to search (one in the sense that there is a unique root starting point), but the implementation of that JNDI could be something vendor-specific, an external LDAP, Active Directory, etc.

[Stan James]

I've used them frequently for caches, factories and statistics utilities like a hit counter.

[B.Sathish]

Thread pools, connection pools, registry objects, objects handling user preferences, caches