singleton method in collections class

[saikrishna cinux]

what sake the Collections class is meant for and what is the actual use of Singleton method ?
where it is used?
advantages?


thanks in advance

[Jeanne Boyarsky]

Saikrishna,
The Collections class provides utility methods for dealing with different types of Collections (Lists, Maps and Sets.)

The singleton method gives you a set with one object. (there are also list and map versions of this method.) Since the set is immutable (cannot be changed), Java is free to give you the exact same set if you later make the same method call.