Scala - LinkedIn Skill Assessments Quizzes with Answers


Q1. 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.

Q2. What value does this code return?

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

Q3. What is one way to avoid low-level parallelization details?

  • monads
  • literal functions
  • partially applied functions
  • parallel collections

Q4. What do you use in ScalaTest to see a detailed diagram of error messages when a test fails?

  • ArgumentExceptions
  • AssertionException
  • DiagrammedAssertions
  • JUnit

Q5. 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

Q6. After defining a function in the interpreter, Scala returns the following. What does the () indicate?

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.

Q7. What type of number is 1234.e5?

  • hexadecimal
  • short
  • floating point
  • long

Q8. 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[(Collection, Collection)]
  • List

Q9. What type of object does this code create?

val x = (1234, "Active")
  • List
  • Map
  • Tuple
  • Array

Q10. Which is a subclass of all classes?

  • AnyVal
  • AnyRef
  • Method
  • Null

Null in Scala Standard library. The question is a bit incorrect - Null is a subtype of every type except those of value classes

Q11. 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.
  • 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.

Example: yield-body has access to the e variable from the for-body

val a = Array(1, 2, 3, 4, 5)
for {
     e <- a if e > 2
} yield e

Q12. What is one way to implement pattern matching on methods?

  • using regex
  • using monads
  • using string matching
  • using case classes

Note: ambiguous question, it’s not clear what kind of pattern matching is meant here.

Q13. 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))

Q14. What term is used to specify a precondition?

  • assert
  • require
  • precondition
  • mustHave

Q15. Which Scala type may throw an exception or a successfully computed value, and is commonly used to trap and propagate errors?

  • scala.util.ExceptionHandling
  • scala.Catch.Throw
  • scala.exception.TryFinally
  • scala.util.Try


Q16. What is the data type of y after this code is executed?

val y = (math floor 3.1415 * 2)
  • short
  • double
  • int
  • bigInt

Q17. When using pattern matching, which character matches on any object?

  • %
  • _
  • ^
  • -

Pattern Matching

Q18. 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.


val a1 = Array(1, 2, 3)
a1{1} = 3 // OK
a1 = Array(1, 3, 3) // error: reassignment to val

Q19. 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

Q20. What do you call objects with immutable state?

  • singletons
  • stationary objects
  • functional objects
  • fixed objects

Note: singletons may have mutable state

Q21. 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

Q22. What does this code return? val x = 3; if (x > 2) x = 4 else x = x*2

  • 4
  • an error
  • 6
  • 3

Q23. 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)

Q24. To denote a parameter that may be repeated, what should you place after type?

  • %
  • &
  • _
  • -

Q25. What is called when a superclass has more than one subclass in Scala?

  • polyinheritance
  • multilevel inheritance
  • multimode inheritance
  • hierarchical inheritance

Q26. One way to improve code reliability is to use __ , which will evaluate a condition and return an error if the condition is violated.

  • packages
  • polymorphisms
  • assertions
  • traits

Q27. 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.

Q28. What do you call the process of changing the definition of an inherited method?

  • recursive methods
  • currying methods
  • redefining methods
  • overriding methods

Q29. To denote a parameter that may be repeated, what should you place after the type?

  • _
  • *
  • %
  • &

Repeated Parameters in Scala

Q30. 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))

Q31. 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.

Q32. 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

Q33. What can you use to make querying a database more efficient, by avoiding the need to parse the SQL string every time a query is executed from Scala?

  • database driver
  • connection
  • prepared statement
  • SQL view

PreparedStatement from Java which is also used in Scala

Q34. Which is not a member of the collections hierarchy?

  • Set
  • Seq
  • Hash
  • Map

Q35. Which term makes the contents of packages available without prefixing?

  • use
  • include
  • import
  • assertion

Q36. If you wanted to find the remainder after division, what operator would you use?

  • %
  • DIV
  • //
  • /

Q37. What are defined inside a class definition?

  • method
  • fields and methods
  • fields, methods, and packages
  • fields

Q38. What defines methods and fields that can then be reused by mixing into classes?

  • singleton
  • assertion
  • trait
  • monad

Q39. When do you need to explicitly state the return type in a function definition?

  • when the function has no side effects
  • when the function returns a Unit type
  • when the function is recursive
  • when the function has side effects

Q40. Why would you make a field private?

  • so only methods in the same file can access the field
  • so only methods in the same package can access the field
  • so only methods in the same class could access the field
  • so only methods defined in a Java class can access the field

Q41. What’s the difference between .equals and ==?

  • They do the exact same thing
  • == won’t work on objects
  • == cannot be applied to String
  • == is a wrapper of .equals() and checks for nulls


Q42. What is denotes the intersection between two sets?

  • ||
  • &&
  • &
  • %


Q43. What’s the best way to execute code in the background in a separate thread?

  • AltFuture
  • Future
  • AltProcess
  • AltThread

Q44. What do you call a function defined in a block?

  • private function
  • block function
  • local function
  • method

Q45. What do you call a Scala method that is parametrized by type as well as by value?

  • multimode method
  • polymorphic method
  • closure
  • collection method

Q46. What type of exception is thrown when a precondition is violated?

  • IllegalArgumentException
  • NumberFormatException
  • NullPointerException
  • MalformedParameterException

Q47. In scala what is precondition?

  • a constraint on where a method may be called from
  • a constraint on values passed to a method constructor
  • a class of predefined error messages
  • a class of Boolean operators

Q48. What would you change in this code to make it execute in parallel?

 val myNums = (1 to 500).toList + 1)
  • Change to
  • Change toList to toListPar
  • Change val to val.par
  • Change toList to toParallelList

Q49. What is a free variable?

  • a variable defined outside a function
  • a variable referenced in a function that is not assigned a value by that function
  • a variable that has a global scope
  • a variable defined in a class and available to all methods in that class

Q50. What is the difference between .equals() and == ?

  • == is wrapper of .equals() and checks for Nulls
  • They do the exact same thing.
  • == cannot be applied to String.
  • == won’t work on objects

Q51. What’s the best way to execute code in the background in a separate thread?

  • AltThread
  • AltFuture
  • AltProcess
  • Future

Q53. What value does this code return?

x= List(1,2,4); x(1)?
  • (1,2,4)
  • 1
  • Nil
  • 2

Hope you find this helpful!

Keep smiling 😄

Darsh Jariwala
Darsh Jariwala

A web geek, game lover residing in India 🇮🇳