Wrapper Classes in Java

Wrapper Class:

In wrapper class we have Objects which stores primitive data type or which wraps primitive data types.

Advantages:

1. We cannot pass Primitive data type data between two application over the Internet.So Wrapper class needed in that case.
2. When we send data to server then the server expects data to be in object format rather than primitive type of data.
3. Objects in wrapper class can hold primitive data types.

    Syntax:

                    Integer  i = new Integer(123);
                    Float f = new Float(45f);

same for the  remaining wrapper classes.

Primitive Data Types	Wrapper Classes
int	Integer
byte	Byte
char	Character
short	Short
long	Long
float	Float
double	Double
boolean	Boolean

Wrapper  classes have boxing and unboxing.

Boxing:

          boxing means converting primitive data type to objects is boxing. 

 Ex:

                    int i=10;   // primitive type

           

               Integer obj=new Integer(i);   //coverting to objects

          

                System.out.println(obj);

Output:

           10

UnBoxing:

              unboxing means converting objects to corresponding primitive data type is unboxing.

Ex:

               int i=10;   // primitive type

           

               Integer obj=new Integer(i);   //coverting to objects

                int  j = obj.intValue();  //converting to primitive type:unboxing

   

                System.out.println(j);

Output:

          10