Runtime polymorphism in Java - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a method that can be overridden.

Java

public class Animal {
    public void [1]() {
        System.out.println("Animal sound");
    }
}

Drag options to blanks, or click blank then click option'

AmakeSound

Bspeak

Csound

Dnoise

Attempts:

3 left

💡 Hint

Common Mistakes

Using a method name that is not descriptive or inconsistent with subclass methods.

The method name makeSound is used to demonstrate runtime polymorphism by overriding it in subclasses.

2fill in blank

medium

Complete the code to override the method in the subclass.

Java

public class Dog extends Animal {
    @Override
    public void [1]() {
        System.out.println("Bark");
    }
}

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AmakeSound

Bnoise

Cspeak

Dsound

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different method name that does not override the superclass method.

The subclass Dog overrides the makeSound method to provide its own implementation.

3fill in blank

hard

Fix the error in the code to call the overridden method at runtime.

Java

Animal myAnimal = new Dog();
myAnimal.[1]();

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Asound

BmakeSound

Cspeak

Dnoise

Attempts:

3 left

💡 Hint

Common Mistakes

Calling a method name that does not exist in the superclass reference.

Calling makeSound() on the Animal reference invokes the overridden method in Dog at runtime.

4fill in blank

hard

Fill both blanks to complete the code that demonstrates runtime polymorphism with two subclasses.

Java

Animal myAnimal1 = new Dog();
Animal myAnimal2 = new Cat();
myAnimal1.[1]();
myAnimal2.[2]();

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AmakeSound

Bsound

Cspeak

Dnoise

Attempts:

3 left

💡 Hint

Common Mistakes

Using different method names for each call that do not exist in the superclass.

Both Dog and Cat override the makeSound() method, so calling it on Animal references demonstrates runtime polymorphism.

5fill in blank

hard

Fill all three blanks to complete the code that uses runtime polymorphism with method overriding and dynamic method dispatch.

Java

class Animal {
    public void [1]() {
        System.out.println("Animal sound");
    }
}

class Dog extends Animal {
    @Override
    public void [2]() {
        System.out.println("Bark");
    }
}

public class Test {
    public static void main(String[] args) {
        Animal myAnimal = new Dog();
        myAnimal.[3]();
    }
}

Drag options to blanks, or click blank then click option'

AmakeSound

Bsound

Cspeak

Dnoise

Attempts:

3 left

💡 Hint

Common Mistakes

Using different method names in declaration, override, or call causing compile errors.

The method makeSound() is declared in Animal, overridden in Dog, and called on an Animal reference holding a Dog object to demonstrate runtime polymorphism.