Inheritance limitations in Java - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a class that cannot be extended.

Java

public [1] class Vehicle {}

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

Astatic

Bfinal

Cabstract

Dprivate

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'abstract' instead of 'final' to prevent inheritance.

Using final before a class means it cannot be inherited by other classes.

2fill in blank

medium

Complete the code to prevent a method from being overridden in subclasses.

Java

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

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

Aabstract

Bstatic

Cprivate

Dfinal

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'static' which changes method behavior but does not prevent overriding.

The final keyword before a method means subclasses cannot override it.

3fill in blank

hard

Fix the error in the code by choosing the correct keyword to allow inheritance.

Java

[1] class Shape {}

public class Circle extends Shape {}

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

Apublic

Babstract

Cfinal

Dprivate

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'final' which prevents inheritance.

The class must be public (or default) and not final to allow inheritance.

4fill in blank

hard

Fill both blanks to declare an abstract class with an abstract method.

Java

public [1] class Device {
    public [2] void start();
}

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

Aabstract

Bfinal

Dstatic

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'final' for abstract methods or classes.

An abstract class can have abstract methods without body.

5fill in blank

hard

Fill all three blanks to override a method and prevent further overriding.

Java

public class Parent {
    public void greet() {
        System.out.println("Hello from Parent");
    }
}

public class Child extends Parent {
    @Override
    public [1] void greet() {
        System.out.println("Hello from Child");
    }
}

public class GrandChild extends Child {
    @Override
    public void greet() {
        [2].greet();
        System.out.println("Hello from GrandChild");
    }
}

// To prevent GrandChild from overriding greet(), add [3] keyword in Child class method.

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

Afinal

Bsuper

Dstatic

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to override a final method causes a compile error.

Marking the Child's greet() method as final prevents GrandChild from overriding it. The super keyword calls the parent's method.