Method overloading is one of the ways that Java implements
polymorphism. It allows related methods to be accessed by
use of a common name. Use it when you actually do need
multiple methods with different parameters, but the methods
do the same thing.

overloading is used to achieve reusability and extensibility

Overloading is actually belongs to the concept of 
Polymorphism the most important feature of OOP.
And it simply means "Ability to take more than one form".

In a Progarm when a same method(having ame name, return 
type,argument list) is used to perform multiple or 
different tasks its called as method overloading.

Suppose u write a method having two parameter and name of
that method is sum..................that is

public void sum(int a, int b)
{

}
Now suppose later the requirement is modified and u have to
told now sum method should pass three parameter in subclass,
and both the parameter which is called in superclass should
be same............what u gonna do .........

So u have to write to method in subclass one with two
parameter and another with three parameter and suppose again
the parameter increased and due to which u have to write 100
method like that...........that is sucide attempt for a
developer.

So sun told dont worry use the concept of overloading....
same class name with different parameter.......no need to
write the different method........for the same task....

use same method with different parameter is called overloading.

Some times same Object should act differently in differnet 
places and in different time . In that case java goes with 
overloading.