Kotlin: Cannot create an instance of an abstract class

Kotlin: Cannot create an instance of an abstract class

In this tutorial, we shall learn to fix Kotlin: Cannot create an instance of an abstract class.

Following is a sample of the error you might get during compilation.

Error:(2, 27) Kotlin: Cannot create an instance of an abstract class

Solution

In Kotlin, we cannot create an instance of an abstract class.

Abstract class could only be inherited by a class or another Abstract class. So, to use abstract class, create another class that inherits the Abstract class.

Following is an example that demonstrates the usage of kotlin abstract class.

Kotlin Program – example.kt

/**
 * Abstract Class
 */
abstract class Vehicle {
    // regular variable
    var name : String = "Not Specified"
    // abstract variable
    abstract var medium : String
    // regular function
    fun runsWhere() {
        println("The vehicle, $name, runs on $medium")
    }
    // abstract function
    abstract fun howItRuns()
}

/**
 * inheriting abstract class
 */
class Aeroplane : Vehicle() {
    // override abstract variables and functions of the
    // abstract class that is inherited
    override var medium: String = "air"

    override fun howItRuns() {
        println("Aeroplane fly based on buoyancy force.")
    }

}

fun main(args: Array<String>) {
    var vehicle1 = Aeroplane()
    vehicle1.howItRuns()
}

Output

Aeroplane fly based on buoyancy force.