what is polymorphism?

Answer Posted / ganesh

Overloaded methods are methods with the same name signature
but either a different number of parameters or different
types in the parameter list. For example 'spinning' a
number may mean increase it, 'spinning' an image may mean
rotate it by 90 degrees. By defining a method for handling
each type of parameter you achieve the effect that you want.

Overridden methods are methods that are redefined within an
inherited or subclass. They have the same signature and the
subclass definition is used.

Polymorphism is the capability of an action or method to do
different things based on the object that it is acting
upon. This is the third basic principle of object oriented
programming. Overloading and overriding are two types of
polymorphism . Now we will look at the third type: dynamic
method binding.

Assume that three subclasses (Cow, Dog and Snake) have been
created based on the Animal abstract class, each having
their own speak() method.

Example:
--------
public class AnimalReference
{
public static void main(String args[])
Animal ref // set up var for an Animal
Cow aCow = new Cow("Bossy"); // makes specific objects
Dog aDog = new Dog("Rover");
Snake aSnake = new Snake("Earnie");

// now reference each as an Animal
ref = aCow;
ref.speak();
ref = aDog;
ref.speak();
ref = aSnake;
ref.speak();
}
Notice that although each method reference was to an Animal
(but no animal objects exist), the program is able to
resolve the correct method related to the subclass object
at runtime. This is known as dynamic (or late) method
binding.

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