wrapper class used access the primitive data types as objects.
we cant store primitive data in arraylist,hashtable  so we
using wrapper class used to store primitive data types as
objects,caz objects only can store in collections

A class enclosed or Wrapped the primitive data type is
called wrapper class.

Number class is the super class for Wrapper class. subclass
of Number classes are   Byte,Short,Intger,Long,Float,Double,
Character

primitive values              Wrapper class

byte                          Byte
short                         Short
int                           Integer
long                          Long
float                         Float
char                          Character  

Mostly the wrapper classes are used to pass the date thru
networks/serializable.