Master Your Interview
Top 39 Scala Interview Questions
Entry Junior Mid Senior Expert
Scala Theoretical Questions
Q1:
What are the use of an underscore _ in Scala?
_ in Scala? Entry
Q2:
What is Type Inference in Scala?
Entry
Q3:
What is the difference between Java’s void and Scala’s Unit?
void and Scala’s Unit? Junior
Q4:
What is the difference between class and object in Scala?
class and object in Scala? Junior
Q5:
Is there any difference between ::: and ++ for concatenating lists in Scala?
::: and ++ for concatenating lists in Scala? Junior
Q6:
Give and example of a trait and when are they best used in Scala?
trait and when are they best used in Scala? Junior
Q7:
Explain the difference between for-loop and for-comprehension in Scala?
Mid Q8:
When do we need to avoid Type Inference and declare types implicitly in Scala?
Mid Q9:
What's the difference between Unit and Nothing?
Unit and Nothing? Mid Q10:
How do you append to a list in Scala?
Mid Q11:
What is a companion object in Scala?
Mid Q12:
What is the difference between unapply and apply in Scala, when would you use them?
unapply and apply in Scala, when would you use them? Mid Q13:
What are the differences between a Scala Future and a Java Future?
Future and a Java Future? Mid Q14:
What is difference between Null, Nil and Nothing in Scala?
Null, Nil and Nothing in Scala? Mid Q15:
What are some benefits of using Scala for Data Science?
Mid Q16:
What will be the output of the following code in Scala?
Mid Q17:
Name some purposes that object serves in Scala
object serves in Scala Mid Q18:
What is the difference between Scala's case class and class?
Mid Q19:
What is Type Erasure in Scala?
Mid Q20:
How do you get an element at index i from the List in Scala?
i from the List in Scala? Mid Q21:
What is the difference between def, val and lazy val in Scala?
def, val and lazy val in Scala? Mid Q22:
What is the difference between ArrayBuffer and Array in Scala?
ArrayBuffer and Array in Scala? Mid Q23:
How can we access the value result of a Future?
Future? Mid Q24:
Is there any difference between Case Object and Object in Scala?
Senior Q25:
Explain the difference between TypeTag vs ClassTag vs WeakTypeTag in Scala
TypeTag vs ClassTag vs WeakTypeTag in Scala Senior Q26:
How can we overcome Type Erasure in Scala?
Senior Q27:
Is there any reason to prefer filter+map over collect in Scala?
filter+map over collect in Scala? Senior Q28:
What is the advantage of using Abstract Classes instead of Traits in Scala?
Senior Q29:
What's the difference between Future and Promise in Scala?
Future and Promise in Scala? Senior Scala Practical Challenges
Q1:
What is the difference (if any) between these two statements in Scala?
Junior Q2:
What will be the output of this code in Scala?
Junior Q3:
Rewrite this two variables loop from Java to Scala
Junior Q4:
How to implement the equivalent of Java static methods in Scala?
Junior Q5:
Given a list of tuples List[(A, B)], return a Map[A, List[B]] in Scala. Explain.
List[(A, B)], return a Map[A, List[B]] in Scala. Explain. Mid Q6:
How can you make a List[String] from a List[List[String]] in Scala?
List[String] from a List[List[String]] in Scala? Mid Q7:
Rewrite this Scala code using Feature and Promise
Feature and Promise Senior Q8:
Rewrite this nested for-comprehension loop using functional style code (declarative looping) in Scala
Senior Q9:
Write a function which reverses a List without using loops and the built-in .reverse in Scala
.reverse in Scala Senior Q10:
Calculate the Convex Hull of a given set of points in Scala
Senior 
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