5 Frequently Asked Questions about Scala and Their Answers

With support for functional programming and a strong static type system, Scala is a general-purpose programming language. It has been used quite a lot in the IT world and according to StackOverflow, it is amongst the top 20 most popular programming languages in the world. This is the main reason why people learn Scala for a successful career in the IT industry. Below are some important questions, the answers for which you should know for cracking the job screening process:

Question 1. What is Scala? What are the pros and cons of Scala Language?

Answer. Scala is a general-purpose programming language. It comes with support for functional, object oriented, and imperative programming approaches

Below are some of the benefits of using the Scala Language:

1. 1. High Productivity
2. 2. Distributed Applications
3. 3. Concise and Simple Code
4. 4. Option of Reusable Code
5. 5. High Modularity
6. 6. More Action with Minimum Code
7. 7. Supports Entire OOP Features
8. 8. Enough Flexible Syntax
9. 9. Full Java Interoperability
10. 10. Availability of Powerful Scala DSLs
11. 11. Expressive and Readable Code
12. 12. Highly Functional and Supports all FP Features
13. 13. Lower Vulnerability of Code 
14. 14. Improved Parallel and Concurrency Programming
15. 15. Completely Type-Safe Language
16. 16. Immutability and No Side-Effects

Some of the disadvantages of Scala Language:

1. 1. Complicated Syntax to learn
2. 2. Less Backward Compatibility
3. 3. Code is difficult to read
4. 4. Tough Language to Learn

Question 2. How is function different from methods in Scala Language?

Answer. Scala has the capability to store both functions and methods. There is one minor difference between functions and methods in Scala, which is listed below:

It is possible to describe a method in a Scala class or trait. This method is associated with an object (an instance of a Class). A method can be called by using an instance of a Class. Scala Method cannot be used directly, making use of an object.

The function has no attachment with either a trait or a class. It is defined in a Scala Package. This function can be accessed without utilizing objects like Java’s Static Methods.

Question 3. Describe Scala Map and its functions.

Answer. Scala Map comprises of key value pairs, in which the value in the map can be retrieved by using the key. The values in a Scala Map are different; however, the keys are exclusive.

Two kinds of maps in Scala are supported - mutable and immutable. It is by default that Scala supports immutable map. In order to utilize the mutable map, programmers have to import the scala.collection.mutable.Map class explicitly. In case, a developer wants to use both mutable and immutable maps at the same time in a module, then he can access a mutable map by using mutable.map and the immutable map can be accessed with the name of the map.

Question 4. What is the difference between Val and Var in Scala?

Answer. Just like in Java, Var keyword is used for variable declaration. It refers to the mutable declaration of variables. On the other hand, Val is slightly different. Val is an immutable declaration of variable in Scala and once it is declared, its reference cannot be shifted to point to another reference.

Question 5. Differentiate between ‘Nil’, ‘Null’, and ‘None’ in Scala.

Answer. We can differentiate between these terms as mentioned below:

Null – Null is a sub-type of AnyRef type in Scala Types hierarchy. The fact that, Scala runs on JVM, NULL is used to provide the compatibility with Java null keyword. Besides, in the Scala terms, to provide the type for null keyword, Null type exists. Null represents the lack of type information for complex types inherited from AnyRef.

Nothing – Nothing is a sub-type of all the existing types in Scala hierarchy. It offers the return type of the operations that can affect the flow of a normal program. This sub-type can only be used as a type, as an instantiation of nothing cannot be done. It includes all types under AnyRef and AnyVal. Nothing is generally used as a return type for methods, which have unusual termination and result in an exception.

Nil – It can be used for initializing an empty list.

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