Why does not work

Question

animal class will be inheited by dog and cat class
THIS IS THE CONCEPT

when did i need to declare object like this declaration.this is a compilation error rised...
Dog a=new Dog();
based on the polyporphism concept
example says
animal a=new Dog(); correct!!!

Answer 1

I barely understand what you are saying, but I think your example is about interfaces

Answer 2

bro....based on polymorphism concept,i have a doubt to declare object....
class animal
class dog extends animal
class cat extends animal

in main
animal a=new Dog();
this is concept for declare object for that....

In this , why they use" animal "word

Answer 3

My opinion is this...

The normal way to instantiate class dog would be:
Dog d = new Dog();

But since we know that Dog inherits from Animal, we can upcast an instance of our subclass (Dog) to the superclass (Animal). Hence;
Animal a = new Dog();

I hope that was helpful :-)