Kotlin Programming MCQ for Competitive Exams, Interviews, and Certifications
practice.

What is the type of arr in the following code?

val arr = arrayof(1, 2, 3)

From the Supervisor subclass, how do you call the Employee class's display() method?

open class Employee(){
  open fun display() = println("Employee display()")
}
class Supervisor : Employee() {
  override fun display() {
    println("Supervisor display()")
  }
}

The code below shows a typical way to show both index and value in many languages, including Kotlin. Which line of code shows a way to get both index and value more idiomatically?

var ndx = 0;
for (value in 1..5){
  println("$ndx-$value")
  ndx++
}

This code does not print any output to the console. What is wrong?

firstName?.let {
  println("Greeting $firstname!")
}

What is the equivalent of the following Java expression in Kotlin?

int x = a ? b : c 

You have an enum class Signal that represents the state of a network connection. You want to print the position number of the SENDING enum. Which line of code does that?

enum class Signal { OPEN, CLOSED, SENDING }

What is the output of the following code?

val list : List<Int> = listof(1, 2, 3)
list.add(4)
print(list)

What does the following code print?

val listA = mutableListOf(1, 2, 3)
val listB = listA.add(4)
print(listB)

What is the difference between the declarations of COLOR and SIZE?

class Record{
  companion object {
    const val COLOR = "Red"
    val SIZE = "Large"
  }
}

In the file main.kt, you ae filtering a list of integers and want to use an already existing function, removeBadValues. What is the proper way to invoke the function from filter in the line below?

val list2 = (80..100).toList().filter(_____)

What is the difference between a and b?

var a: String? = "KotlinProgramming"
var b: String = 'KotlinProgramming"

Which is true for the following simple class declaration?

class Person (val name: String)

The code below compiled and executed without issue before the addition of the line declaring errorStatus. Why does this line break the code?

sealed class Status(){
  object Error : Status()
  class Success : Status()
}
fun main(){
  var successStatus = Status.Success()
  var errorStatus = Status.Error()
}

The code below is expected to display the numbers from 1 to 10, but it does not. Why?

val seq = sequence { yieldAll(1..20) }
  .filter { it < 11 }
  println(seq)

You have an unordered list of high scores. Which is the simple method to sort the highScores in descending order?

fun main() { val highScores = listOf(4000, 2000, 10200, 12000, 9030)}

What three methods does this class have?

class Person

In this code snippet, why does the compiler not allow the value of y to change?

for(y in 1..100) y+=2

Both const and @JvmField create constants. What can const do that @JvmField cannot?

class Detail {
  companion object {
    const val COLOR = "Blue"
    @JvmField val SIZE = "Really Big"
  }
}

You have two arrays, a and b. Which line combines a and b as a list containing the contents of both?

val a = arrayOf(1, 2, 3) val b = arrayOf(100, 200, 3000)

When the Airplane class is instantiated, it displays Aircraft = null, not Aircraft = C130 why?

abstract class Aircraft {
  init { println("Aircraft = ${getName()}") }
  abstract fun getName(): String
}
class Airplane(private val name: String) : Aircraft() {
  override fun getName(): String = name
}