Abstract classes and methods in Kotlin - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare an abstract class named Vehicle.

Kotlin

abstract class [1] {
    abstract fun start()
}

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AVehicle

BCar

CDrive

DStart

Attempts:

3 left

💡 Hint

Common Mistakes

Using a function name instead of a class name.

Forgetting to use the abstract keyword.

The keyword abstract is used to declare an abstract class. Here, Vehicle is the class name.

2fill in blank

medium

Complete the code to declare an abstract method named drive inside an abstract class.

Kotlin

abstract class Vehicle {
    abstract fun [1]()
}

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Arun

Bdrive

Cstop

Dstart

Attempts:

3 left

💡 Hint

Common Mistakes

Adding a method body to an abstract method.

Using a method name unrelated to the class.

The abstract method drive is declared without a body inside the abstract class.

3fill in blank

hard

Fix the error in the subclass that inherits from an abstract class and implements the abstract method.

Kotlin

abstract class Vehicle {
    abstract fun drive()
}

class Car : Vehicle() {
    override fun [1]() {
        println("Car is driving")
    }
}

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Amove

Brun

Cstart

Ddrive

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different method name than the abstract method.

Forgetting the override keyword.

The subclass Car must override the abstract method drive from the superclass Vehicle.

4fill in blank

hard

Fill both blanks to create an abstract class with an abstract method and a concrete method.

Kotlin

abstract class [1] {
    abstract fun [2]()
    fun stop() {
        println("Stopping")
    }
}

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AMachine

Bstart

Cdrive

DVehicle

Attempts:

3 left

💡 Hint

Common Mistakes

Using a concrete method name as abstract.

Naming the class with a verb instead of a noun.

The abstract class is named Machine. It has an abstract method start and a concrete method stop.

5fill in blank

hard

Fill all three blanks to implement an abstract class and override its abstract method in a subclass.

Kotlin

abstract class [1] {
    abstract fun [2]()
}

class [3] : [1]() {
    override fun [2]() {
        println("Running")
    }
}

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ARunner

Brun

CAthlete

Dstart

Attempts:

3 left

💡 Hint

Common Mistakes

Using the same name for class and subclass.

Not overriding the abstract method correctly.

The abstract class is Runner with an abstract method run. The subclass Athlete overrides run.