When we need to store primitive datatypes as objects, we use
wrapper classes.MEans in utility classes all the utility
classes stores Objects.So when we need to store a primitive
datatype.We make an object of theat primitive data and store it.

   Thats why we use Wrapper classes in Java.

Wrapper classes are classes that allow primitive types to 
be accessed as objects.

wrapper class allows us to make use of primitive datatypes 
as objects

Wrapper classes are classes that allow primitive types to 
be accessed as objects.

Say supposing there is a requirement to store only the
object in an array A.The Primitive types cannot be stored in
the same array as the array can accommodate only Objects
here is where Wrapper Class come into picture.ie, we create
wrapper for the primitive types.One such example is as below

Ex:int i;
Wrapper class for the primitive type(int) is created as below:

INTEGER i = new INTEGER();

wrapper classes is nothing but the primitive datatypes make
as a class name is called a wrapper class

we can't store the different types of objects(primitive 
datatypes can not be stored) in the same array(same types 
of objects can be stored). so, we can crate a primitive 
data type for int i; 
              as INTEGER i = new INTEGEr();
This is the procedure actually going on.

ExAMPLE:

int i=100  // declaration of primitive type.

/* wrapping the primitive data type to corresponding wrapper
class object */

Integer i1=new Integer(i);

A primitive wrapper class in the Java programming language
is one of eight classes provided in the java.lang package to
provide object methods for the eight primitive types. All of
the primitive wrapper classes in Java are immutable. J2SE
5.0 introduced autoboxing of primitive types into their
wrapper object, and automatic unboxing of the wrapper
objects into their primitive value—the implicit conversion
between the wrapper objects and primitive values.

Wrapper classes are used to represent primitive values when
an Object is required. The wrapper classes are used
extensively with Collection classes in the java.util package
and with the classes in the java.lang.reflect reflection
package.

The primitive wrapper classes and their corresponding
primitive types are:

    Primitive type 	Wrapper class 	Constructor Arguments
    byte 	Byte 	byte or String
    short 	Short 	short or String
    int 	Integer 	int or String
    long 	Long 	long or String
    float 	Float 	float, double or String
    double 	Double 	double or String
    char 	Character 	char
    boolean 	Boolean 	boolean or String

The Byte, Short, Integer, Long, Float, and Double wrapper
classes are all subclasses of the Number class.