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.