In Java 1.0 and 1.1, the two primary collection classes were Vector and Hashtable, and the Iterator design pattern was implemented in a class called Enumeration.

Guava brings filtering and transformation on collections to standard Java and that is the subject of this post. Guava’s Collections2 class features two public methods, both of which are static.

Collection in Java represents a single unit of the group. Using Java collection you can perform all the operations on the data like searching, sorting, inserting, manipulation, deletion, etc.