what are singleton classes in Java API

[sirisha makkapati]

Any one Please Tell me

what are singleton classes in Java API

Thanks
Sirisha

[Guru dhaasan]

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

[David McCombs]

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?

[David O'Meara]

"Gurudhaasan",
Welcome to the JavaRanch.

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thanks,
Dave