Help me detect my error

Question

I was going through polymorphism in Java tutorials of Sololearn wherein I found this code snippet.
class Animal {
public void makeSound() {
System.out.println("Grr...");
}
}
class Cat extends Animal {
public void makeSound() {
System.out.println("Meow");
}
}
class Dog extends Animal {
public void makeSound() {
System.out.println("Woof");
}
}

class Program {
public static void main(String args[ ]) {
Animal a = new Dog();
Animal b = new Cat();

a.makeSound();
b.makeSound();
}
}

the above one is the code snippet provided by the Sololearn.

If i add object c for class Animal, the code snippet doesn't work and is showing error. Please help me out

class Animal {
public void makeSound() {
System.out.println("Grr...");
}
}
class Cat extends Animal {
public void makeSound() {
System.out.println("Meow");
}
}
class Dog extends Animal {
public void makeSound() {
System.out.println("Woof");
}
}

class Program {
public static void main(String args[ ]) {
Animal a = new Dog();
Animal b = new Cat();
Animal c = new Animal();

a.makeSound();
b.makeSound();
c.makeSound();
}
}

Answer 1

https://code.sololearn.com/ckMn7mZQVaci/?ref=app

Answer 2

i copied and pasted the code. no edits. it works for me

Answer 3

odd. could you show this in codeplayground?

Answer 4

what error? line number?

Answer 5

The first code snippet gave output as
Woof
Meow
which was as expected. But after adding the object c of class Animal and calling the makeSound() , it didn't work/
using the second code snippet, I wasn't getting any output whereas I expected output for second code snippet to be
Woof
Meow
Grrr....
But the compiler showed some error to me.
Help me out where is the fault in logic.

Answer 6

By adding
Animal c = new Animal();
and c.makeSound();

to the first code snippet , i am receiving error.

Answer 7

It's fine....maybe there is a bug...If it's working fine in ur playground then it's fine. I just wanted to know whether I am committing any logical error or not.
Thanks all of you for your kind concerns. :)