Scala MCQ: Scala Multiple Choice Questions and Answers

Scala MCQ with answers and explanations for placement tests and job interviews. These solved Scala MCQs are useful for the campus placement for all freshers including Engineering Students, MCA students, Computer and IT Engineers, etc.

Our Scala MCQ (Scala Multiple Choice Questions ) focuses on various parts of the Scala programming language and its concept. It will be useful for anyone learning Scala Basics, Essentials, and/or Fundamentals. We will regularly update the quiz and most interesting thing is that questions come in a random sequence. So every time you will feel new questions.

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Guideline of Scala MCQ:

This Scala MCQ is intended for checking your Scala programming knowledge. It takes 40 minutes to pass the Scala MCQ. If you don’t finish the Scala MCQ within the mentioned time, all the unanswered questions will count as wrong. You can miss the questions by clicking the “Next” button and return to the previous questions by the “Previous” button. Every unanswered question will count as wrong. MCQ on Scala has features of randomization which feel you a new question set at every attempt.

In this Scala MCQ, we have also implemented a feature that not allowed the user to see the next question or finish the Scala quiz without attempting the current Scala MCQ.

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Scala MCQ

Scala MCQ: Scala Multiple Choice Questions and Answers

1 / 35

Which is not a member of the collections hierarchy?

Set

Seq

Hash

Map

2 / 35

What is one way to avoid low-level parallelization details?

monads

literal functions

partially applied functions

parallel collections

3 / 35

What is one way to implement pattern matching on methods?

using regex

using monads

using string matching

using case classes

4 / 35

What is the value of z after executing this code?

val y = List('a','b')
val z = y::List('c')

List(a,b,c)

List(List(a, b), c)

List(c,a,b)

List(c,List(a,b))

5 / 35

You have created an array using val. Can you change the value of any element of the array—and why or why not?

Yes, the reference to the array is immutable, so the location that the array points to is immutable. The values in the array are mutable.

The 0th element is immutable and cannot be modified. All other elements can be modified.

Yes, val does not make arrays immutable.

No, val makes the array and values of the array immutable.

6 / 35

Which statement returns a success or a failure indicator when you execute this code?

val MyFuture = Future {runBackgroundFunction() }

myFuture.onComplete

myFuture(status)

myFuture.Finished

complete(myFuture)

7 / 35

What is the data type of y after this code is executed?

val y = (math floor 3.1415 * 2)

short

double

int

bigInt

8 / 35

What is the code below equivalent to?

myClass.foreach(println _)

myClass.foreach(println ())

myClass.foreach(print NIL)

myClass.loop(println ())

myClass.foreach(x => println(x))

9 / 35

You want to create an iteration loop that tests the condition at the end of the loop body. Which iteration would you use?

do-while loop

while loop

for loop

do-until loop

10 / 35

What type of object does this code create?

val x = (1234, "Active")

List

Map

Tuple

Array

11 / 35

For the for-yield construct, is the scope separate between for-body and yield-body?

Yes and no. It is different depending on the for construct and what it does. NOT SURE

Yes, because the for section does not expose its scope.

No, because for-yield shares the same scope, even though they are within separate curly braces.

Yes, because they are within different curly braces.

12 / 35

If you wanted to find the remainder after division, what operator would you use?

DIV

13 / 35

What value does this code return?

val m1 = Map("a"->1,"b"->2,"c"->3)
m1("a")

14 / 35

What are defined inside a class definition?

method

fields and methods

fields, methods, and packages

fields

15 / 35

What do you call the process of changing the definition of an inherited method?

recursive methods

currying methods

redefining methods

overriding methods

16 / 35

After defining a function in the interpreter, Scala returns the following. What does the

myfnc: ()Unit

The function has no side effects.

The function takes no parameters.

The function returns no value.

Returning unit types to the function is a closures.

17 / 35

What is the output of this function?

def main () {
     var a = 0
     for (a<-1 until 5){println(a)}

1,2,3,4,5

0,1,2,3,4

1,2,3,4

2,3,4,5

18 / 35

What term is used to specify a precondition?

assert

require

precondition

mustHave

19 / 35

When you convert a map to a list using the toList method of the map, the result will be of which type?

List[(String, String)]

List[(Array, Array)]

List

20 / 35

Which term makes the contents of packages available without prefixing?

use

include

import

assertion

21 / 35

One way to improve code reliability is to use _, which will evaluate a condition and return an error if the conditions is violated.

packages

polymorphisms

assertions

traits

22 / 35

What does this code return? val x = 3; if (x >2) x = 4 else x = x*2

an error

23 / 35

What do you use in ScalaTest to see a detailed diagram of error messages when a test fails?

ArgumentExceptions

AssertionException

DiagrammedAssertions

JUnit

24 / 35

To denote a parameter that may be repeated, what should you place after type?

25 / 35

Which statement about if-else-if-else statements is true?

If the first else-if does not succeed, then no other else-ifs are tested.

If an else-if does not succeed, then none of the remaining else-if statements or elses will be tested.

All else-if statements are tested in all cases.

If an else-if succeeds, then none of the remaining else-if statements or elses will tested.

26 / 35

Scala bytecode can run on top of Java VM. What is the fundamental difference between Java object.clone() and Scala object.copy()?

One is a Java object, the other is a Scala object.

clone() will copy class structures but not the data, while copy() will also copy data into new objects.

There is no difference.

copy() allows you to change values during the copying process; clone() does not.

27 / 35

What do you call objects with immutable state?

singletons

stationary objects

functional objects

fixed objects

28 / 35

What type of number is 1234.e5?

hexadecimal

short

floating point

long

29 / 35

What is called when a superclass has more than one subclass in Scala?

polyinheritance

multilevel inheritance

multimode inheritance

hierarchical inheritance

30 / 35

When using pattern matching, which character matches on any object?

31 / 35

What data type would you use to store an immutable collection of objects that contain a fixed number of varying types?

Array

ImmutableCollection

List

Tuple

32 / 35

Which is a subclass of all classes?

AnyVal

AnyRef

Method

Null NOT SURE

33 / 35

What is an advantage of an immutable object?

Immutable objects use less memory than their mutable counterparts.

Immutable objects do not require error handling.

Immutable objects can be used in classes, mutable objects cannot.

Immutable objects are threadsafe.

34 / 35

What defines methods and fields that can then be reused by mixing into classes?

singleton

assertion

trait

monad

35 / 35

You have written a Scala script. How would you access command-line arguments in the script?

use array named args

use tuple named args

use numbered variables with a _ prefix for example _ 1, _ 2, _ 3

use numbered variables with a $ prefix - for example $1, $2, $3

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Scala MCQ: Scala Multiple Choice Questions and Answers

Guideline of Scala MCQ:

You have 40 minutes to take the Scala MCQs

Your time has been Over.

When you convert a map to a list using the toList method of the map, the result will be of which type?

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