Why inheritance is used in Java - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a class that inherits from another class.

Java

class Dog extends [1] {}

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ACar

BHouse

CTree

DAnimal

Attempts:

3 left

💡 Hint

Common Mistakes

Using a class unrelated to the child class as the parent.

Forgetting to use the 'extends' keyword.

In Java, a class inherits from another class using the extends keyword followed by the parent class name. Here, Dog inherits from Animal.

2fill in blank

medium

Complete the code to call the parent class constructor from the child class.

Java

class Dog extends Animal {
    Dog() {
        super[1];
    }
}

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A()

B{}

C[]

D;

Attempts:

3 left

💡 Hint

Common Mistakes

Using curly braces instead of parentheses.

Omitting parentheses after super.

The super() call invokes the parent class constructor. Parentheses are needed to call it as a method.

3fill in blank

hard

Fix the error in the code to override a method from the parent class.

Java

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

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Aspeak

Bbark

Crun

Djump

Attempts:

3 left

💡 Hint

Common Mistakes

Changing the method name when overriding.

Forgetting the @Override annotation.

The method speak() is overridden from the parent class Animal. The method name must match exactly to override.

4fill in blank

hard

Fill both blanks to create a subclass that inherits and adds a new method.

Java

class [1] extends Animal {
    public void [2]() {
        System.out.println("Runs fast");
    }
}

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ACheetah

Bfly

CrunFast

DBird

Attempts:

3 left

💡 Hint

Common Mistakes

Using unrelated class names.

Using method names that don't describe the action.

The class Cheetah inherits from Animal and adds a new method runFast() to show its behavior.

5fill in blank

hard

Fill all three blanks to complete the code that demonstrates inheritance and method overriding.

Java

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

class [2] extends [3] {
    @Override
    public void sound() {
        System.out.println("Meow");
    }
}

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

AAnimal

BCat

DDog

Attempts:

3 left

💡 Hint

Common Mistakes

Using different class names that don't match inheritance.

Not overriding the method correctly.

The Cat class inherits from Animal and overrides the sound() method to print "Meow" instead of the generic animal sound.