LinkedIn Scala Assessment Answers 2022

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)
m1("a")

  •  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

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 closure.

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[(Array, Array)]
  •  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 NOT SURE

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. 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.

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

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

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?

answers missing

The answer should be Option: Some or None


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?

  •  %
  •  \_
  •  ^
  •  -

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.

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

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
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