To help you with your interview, here are six Scala interview questions with example answers to help you prepare your own responses while interviewing for a role as a Scala Software Engineer.
1. What is Scala?
An interviewer may ask this type of question at the start of your interview. General questions like this can help a prospective employer gain a better understanding of your overall comprehension of various programming languages. This type of question also assesses how well you can explain programming concepts or terms using simplified language. In your answer, use specific but easy-to-understand language that professionals from a range of both tech and non-tech fields can understand.
Example: "Scala is the abbreviated term for a coding language called Scalable Language. This multi-paradigm language supports both object-oriented and functional programming, which means that it supports data values with either fixed or permanent values. Scala's motto is, "Do more with less," because the primary goal of this language is to express coding solutions and features as concisely as possible."
2. What is a Scala map?
You may get asked this question during the first part of your interview to gauge your understanding of various Scala components. Provide a concise definition of what the feature is and a brief explanation of what it does. You may also want to mention if there are different categories related to the definition.
Example: "A Scala map refers to a group of key or value pairs. Coders can use unique keys to access the values present within the map. The two chief types of Scala maps are mutable and immutable. In an immutable map, you can't change the objects' values after you've set them, but with a mutable one, you can. The default map for Scala is the immutable one."
3. Explain how function currying works.
Some interviewers may ask you to describe how a feature of Scala operates. You may get asked this question to evaluate your understanding of when to use unique elements of Scala coding. Use your answer as an opportunity to demonstrate your knowledge of both how Scala features work and when coders can benefit from using them.
Example: "Scala currying allows programmers to transform a function consisting of multiple arguments into a series of arguments that contain one argument each. Currying may be a good idea if you want to design a program capable of frequently calling some of the same functions with identical parameters. Currying a function makes it easier to refactor, meaning that you can change the structure of the code without modifying its performance features for the end-user. "
4. What are some advantages of using Scala?
This shows your knowledge of and ability to use this coding language compared to other languages. In your answer, focus on the positive aspects of Scala rather than the potential drawbacks of other coding languages.
Example: "One of the primary advantages of Scala is that it allows coders to program with concise language. Because of this coding efficiency and ease in scalability, programmers can often reach the software development or testing stages faster with Scala. Since Scala's designed to handle immutability, another advantage of this program is that it can offer both coders and users greater flexibility in executing functions with changing data. Also, since Scala uses a simplified language with, for example, no explicit punctuation, Scala tends to be less susceptible to errors."
5. What's the difference between a statically typed language and a dynamically typed language? Which type is Scala?
This type of interview question usually aims to assess your knowledge of and ability to use various coding languages. In your answer, you can explain not only the key differences between the two languages you're comparing, but also highlight the benefits that each can offer.
Example: "Scala is a statically typed programming language. This means that the compiler performs type-checking as it's compiling. Dynamically typed language is the opposite. With dynamically typed language, the program performs its type check at run-time instead, as this type of code eliminates the compiling step entirely. Statically typed programming languages like Scala can help minimize the number of errors that programmers encounter prior to runtime. However, dynamically typed languages might support more polymorphic functions, meaning that it may allow more objects or functions to take on different forms."
6. How does a Unit in Scala differ from a void in Java?
Since Scala coders often use Java bytecodes or virtual machines, a prospective employer may ask you interview questions comparing Java features to Scala ones. When you provide an answer, show that you understand both the differences and similarities between Java and Scala.
Example: "Both Units in Scala and voids in Java represent functions or methods that return nothing. However, there are several key differences between them. One of those differences is that Java's void possesses no value, whereas a Unit in Scala has one value consisting of simply two parentheses. Another distinction between the two is that Java's void is a keyword. A Scala Unit, however, is a final class."