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what are singleton classes in Java API

sirisha makkapati
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Joined: Dec 10, 2006
Posts: 83
Any one Please Tell me

what are singleton classes in Java API

Thanks
Sirisha
Guru dhaasan
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Joined: Sep 13, 2006
Posts: 126

basically singleton class allows only one instance of the class to be created at any time


Thanks, Shiv
SCJP, OCE - JSP & Servlets Developer
David McCombs
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Joined: Oct 17, 2006
Posts: 212
Are you asking what a singleton is or what classes in the API implement that pattern?

If the former, a search on this site should prove useful as it is a often talked about topic.

If the latter, look for a class with a private constructor AND has a static method named something like getInstance() or getNameOfClass. If a constructor is not shown in the API it is private.

A well known singleton is Runtime, but there are many more. Another possibility is MessageDigest. Although that one has a protected constructor, so I am not sure it can be considered a singleton. Anyone know?


"Should array indices start at 0 or 1? My compromise of 0.5 was rejected without, I thought, proper consideration."- Stan Kelly-Bootle
David O'Meara
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Joined: Mar 06, 2001
Posts: 13459

"Gurudhaasan",
Welcome to the JavaRanch.

We're a friendly group, but we do require members to have valid display names.

Display names must be two words: your first name, a space, then your last name. Fictitious names are not allowed.

Please edit your profile and correct your display name since accounts with invalid display names get deleted, often without warning

thanks,
Dave
 
With a little knowledge, a cast iron skillet is non-stick and lasts a lifetime.
 
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