Scala Aptitude Test - MCQ Questions with Answers

This post presents a Scala programming aptitude test with 25 multiple-choice questions for beginners. These beginner-level MCQ questions cover essential aspects of Scala programming and are designed to test fundamental understanding and basic syntax.

1. Which is the correct way to declare a variable in Scala?

a) var x = 10
b) var x: Int = 10
c) int x = 10
d) x = 10: var

2. What does the val keyword signify in Scala?

a) That the variable can be reassigned
b) That the variable cannot be reassigned
c) That the variable is mutable
d) That the variable is a type of function

3. How do you define a method in Scala?

a) def methodName {}
b) def methodName() = {}
c) methodName() def = {}
d) def methodName: () = {}

4. What is the output of the following Scala code: println("Hello, Scala".length())?

a) Hello, Scala
b) 11
c) 12
d) 13

5. Which collection in Scala is immutable?

a) ArrayBuffer
b) ListBuffer
c) List
d) MutableList

6. What is the Scala construct for iterating over collections?

a) for loop
b) foreach
c) Both a and b
d) loop

7. Which keyword is used to handle exceptions in Scala?

a) try
b) catch
c) exception
d) try and catch

8. What is the Scala feature that allows the creation of anonymous functions?

a) Lambda
b) Closure
c) Function
d) Method

9. How do you create an array with 5 elements of type Int in Scala?

a) Array
b) new Array
c) Array(5)
d) new Array(5)

10. What does the trait keyword define in Scala?

a) An interface
b) A class
c) A special function
d) A data type

11. How is a constant defined in Scala?

a) const name = value
b) val name = value
c) final name = value
d) fix name = value

12. Which method would you use to concatenate two lists in Scala?

a) ++
b) concat
c) +
d) append

13. How do you define a class in Scala?

a) class ClassName {}
b) new ClassName {}
c) ClassName class {}
d) create class ClassName {}

14. What is pattern matching in Scala?

a) Switching between different patterns
b) A method to search for specified patterns in the text
c) A feature that allows checking a value against a pattern
d) A type of data declaration

15. How do you access the first element of a list in Scala?

a) list[0]
b) list(0)
c) list.first
d) list.get(0)

16. What is an implicit parameter in Scala?

a) A parameter that is passed automatically by the compiler
b) A parameter that must be explicitly passed
c) A hidden parameter that cannot be accessed
d) A parameter passed implicitly by the user

17. What are case classes used for in Scala?

a) Pattern matching
b) Switch statements
c) Defining variables
d) Declaring classes that are mutable

18. What is the Scala REPL used for?

a) Compiling Scala code
b) Running Scala scripts
c) Interactive Scala programming
d) Reporting errors in Scala code

19. What does the object keyword in Scala define?

a) An instance of a class
b) A static class
c) A singleton object
d) A new type

20. How is immutability achieved in Scala?

a) Using private variables
b) Using the immutable keyword
c) Using val instead of var
d) All variables are immutable by default

21. What is the use of the sealed keyword in Scala?

a) To prevent a class from being extended
b) To seal methods within a class
c) To allow classes to be extended in the same file
d) To make a class abstract

22. How do you declare a higher-order function in Scala?

a) func x()
b) def x(f: Int => Int)
c) highorder(f: => Int)
d) function x(f: (Int) => Int)

23. What does the lazy keyword in Scala do?

a) Delays variable initialization until it is accessed
b) Makes code execution faster
c) Creates asynchronous computations
d) Declares a lazy class

24. What is the difference between var and val in Scala?

a) var is mutable, val is immutable
b) var is immutable, val is mutable
c) Both are mutable
d) Both are immutable

25. How do you handle exceptions in Scala?

a) Using the exception block
b) Using the try-catch block
c) Using the error block
d) Using the fault block