Why bark method can not be called

Question

class Animal{
    void run() {
    }
}
class Dog extends Animal {
    void bark() {
    }
}
class Testing{
    public static void main(String[] args)  {
        Animal d         


        

Answer 1

This is how its work.

When compiler try to detect who is d.? its see.

Animal d

Compiler doesn't know know how its created, look at the reference type. So, d is an Animal.

Now the reference is Animal. Does Animal have a bark() method? no. ERROR.

May be d is a Dog inside but compiler doesn't know that and compiler shouldn't know, Compiler translate what you said about d in that case. That's why you getting the error.

Now you can tell that I want d to act as Dog because I know d is a Dog by,

((Dog) d);

and then call bark()

((Dog) d).bark();

So compiler will take d as a Dog only for this operation.