Singleton class

The singleton design pattern allows to have one and only one instance of an object to be created within the whole application.

Singleton class

Singleton class

     

Singleton Design Pattern:

The singleton design pattern allows to have one and only one instance of an object to be created within the whole application. This can be achieved in java by making a Singleton  class

Benefits: 
Singleton pattern provides 
-- access only to the unique instances,
-- permits a variable number of instances, 
-- provides more flexibility than class operations. 
-- it reduces name space, and 
-- allows refinement of operations and representations, 

Usage: 
-- It is used only at those places where the user requires only one instance of a class to be operating through out the application. 
-- It is mostly used in the multi-threaded environments.
-- They often work as global variables permitting the allocation and initialization whenever required. 

Read more at:

www.roseindia.net/java/beginners/SingletonPattern.shtml