What is a Wrapper class?

Wrapper classes wrap primitive values in a class and offers utility to access them through objects. Some of the primitive wrapper data types are:
Byte, short, int, long, float, double, char, Boolean.
Example:
Create a class name VectorAdd to populate it with integer values using the add(int, object) method.
public class VectorAdd
{
       public static void main(String argv[])
       {
             Vector v = new Vector();
             v.add(0,new Integer(10));
             v.add(1,new Integer(20));
             v.add(2,new Integer(30));
             for(int i=0; i < v.size();i ++)
             {
                  Integer iw =(Integer) v.get(i);
                  System.out.println(iw);
             }
       }
}