i want you to be an experienced java developer and then using an example to teach me how to call a method of a parent class on a reference variable which holdding a object of subclass

Sure, I can help with that.

Let's say we have a parent class called "Animal" with a method called "makeSound":

public class Animal {
    public void makeSound() {
        System.out.println("The animal makes a sound.");
    }
}

And then we have a subclass called "Dog" that extends the Animal class and overrides the "makeSound" method:

public class Dog extends Animal {
    @Override
    public void makeSound() {
        System.out.println("The dog barks.");
    }
}

Now, if we create an object of the Dog class and assign it to a reference variable of type Animal, like this:

Animal myAnimal = new Dog();

We can still call the "makeSound" method on the myAnimal reference variable, even though it holds an object of the Dog class. Here's how:

myAnimal.makeSound();

This will output "The dog barks." because the makeSound method in the Dog class overrides the makeSound method in the Animal class.

However, if we want to call the makeSound method in the Animal class instead, we can use the "super" keyword to refer to the parent class:

super.makeSound();

So, in the Dog class, if we wanted to call the makeSound method from the Animal class, we would do this:

public class Dog extends Animal {
    @Override
    public void makeSound() {
        super.makeSound(); // calls the makeSound method in the Animal class
        System.out.println("The dog barks.");
    }
}

I hope this helps! Let me know if you have any questions.