Scala Interview Questions and Answers

What is Scala?
Scala is a type-safe JVM language that incorporates both object oriented and functional programming into an extremely concise, logical, and extraordinarily powerful language.
Scala is written to run in the JVM.

Scala combines object-oriented and functional programming in one concise, high-level language. Scala static types help avoid bugs in complex applications, and its JVM and JavaScript runtimes let you build high-performance systems with easy access to huge ecosystems of libraries.

Is Scala open source?
Yes! Scala is an open source project.

What are the advantages of Scala?
Among various other benefits of the language, here are few-
1.      It is easy to write, compile, debug and run the program
2.      It is highly scalable, testable, maintainable and productive
3.      Your code is more concise, readable and error-free
4.      It facilitates concurrent programming
5.      It is both object-oriented and functional
6.      It has no boilerplate code
7.      Singleton objects are a cleaner solution than static
8.      Scala arrays use regular generics
9.      Scala has native tuples and concise code

What is the Main drawback of Scala Language?
1.      Hard to learn
2.      Scala has a limited developer pool.
3.      Limited community presence
4.      Lack of ease of adoption
5.      Limited backward compatibility

When to use Scala?
1.      Solve concurrency problems
2.      Perform DSL related tasks
3.      Implement functional solutions
4.      Integrate with shared resources, files, databases or multiple backend processes and services
5.      Learn a new development paradigm

Is Scala easy to learn?
It is harder to learn than Java but easy to learn for a Java programmer.

Which is the latest version?
The latest version of Scala 2.12.7

Which keyword is used to define a function in Scala?
The “def” keyword is used to define Scala function.

What is Type Inference in Scala?
Scala has a built-in type inference mechanism which allows the programmer to omit certain type annotations.

Why Scala is used in spark?
Spark is written in Scala and because of its scalability on JVM.
Scala is better than many other traditional data analysis tools like R or Python.

Why do we need App in Scala?
App is a helper class that holds the main method.

Is Scala a functional language?
Scala is a multi-paradigm programming language; it supports imperative and functional style.

What is the Default access modifier in Scala?
The “Public” is the default access modifier in Scala.

What are Scala Identifiers?
Four types of Scala Identifiers-
1.      Alphanumeric identifiers
2.      Operator identifiers
3.      Mixed identifiers
4.      Literal identifiers

What is functional programming?
Functional programming is a style of programming where pure functions and immutable values are the basic building blocks.

Scala vs. Java?
1.      Java complex syntax but Scala simple syntax
2.      Java requires lengthy codes to be written but Scala shorter codes for the same purpose.
3.      Java rewriting is needed but Scala rewriting is not required.
4.      Java dynamics in nature but Scala statically-typed
5.      Java no assurance of bug-free codes but Scala assurance of lesser defects

The Java example looks like -
List<String> list = new ArrayList<String>();

The Scala example looks like -
val list = List("11", "12", "13")

What is the superclass of all classes in Scala?
The “Any” class is the superclass of all classes in Scala.

What is similar between Scala Int and Java’s  java.lang.integer?
Both are used to define Integers, both are classes and both are 32-bit signed integer.

What is Scala Seq?
Scala Seq or Scala sequence is a quality that signifies the indexed sequencing in Scala and which is immutable.

What is REPL in Scala?
REPL stands for Reading Evaluate Print Loop and most of people called “Ripple”. It is an interpreter to execute Scala code from the command prompt.

What do you mean by Option in Scala?
It is used for wrapping the missing value.

What makes it so special over other available programming languages?
1.      It is object-oriented in nature
2.      Includes functional programming features as well
3.      Reflects concurrent and synchronize processing ability

What is the difference between ‘val’ and ‘var’?
If the variable is declared with the keyword “val” it means it’s immutable, cannot be reassigned to a new value.  Mutable variables are declared with the keyword “var“.

Give some examples of JVM Language?
Java, Scala, Groovy, and closure are very popular for JVM language.

What is Null in Scala?
Null is a Type in Scala. It is available in Scala package as “scala. Null”.

What is Scala Trait?
Scala Trait is use to enables the Multiple Inheritance.

What are different types of Literals in Scala?
1.      Integer
2.      Floating point
3.      Boolean
4.      Symbol
5.      Character
6.      String
7.      Multi-Line Stings

What companies use Scala?
1.      LinkedIn
2.      Twitter
3.      Foursquare
4.      Netflix
5.      Tumblr

What are the popular JVM Languages available now?
The most common JVM languages are-
1.      Clojure
2.      Scala
3.      Groovy
4.      JRuby
5.      Jython
6.      Kotlin

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