Scala Interview Questions
In this article, see a list of Scala interview questions and answers.
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Let me guess, you are having your Scala interview scheduled and you are here to know what's in store for you in the interview. Well.....that would be the probable reason you opened this blog. So, without further ado, I'll start the topic.
What Is Scala?
Scala is a high-level language, statically typed language that supports OOPS concepts as well as functional programming concepts. The language Scala is written in Java(optional).
This might persuade the interviewer to ask about the difference between the statically typed language and the dynamically typed language.
In a statically typed language, the type checking is done at the compile-time, and in dynamically typed languages the type checking is done at the run time.
This would be one of the first questions in any Scala interview. Please keep in mind that the interviewer is not looking for a brilliant out of the box answer for this one. A simple answer like this would be good.
What is Scala REPL?
Scala REPL is Read-Evaluate-Print-Loop. It is the command-line interpreter designed for Scala.
What is the difference between Val and var types of variables?
Val - Immutable
var - Mutable
Is switch statements available in Scala?
No, instead of switch Scala uses match statements, which is similar to switch statements.
Does Scala support the use of frameworks?
Yes, Scala supports the use of frameworks like Play Framework, Akka Framework, etc.
What are Streams in Scala?
As Scala supports lazy evaluation, Streams are nothing but lazy lists. The elements in a stream are evaluated lazily(only when they are needed). A stream is constructed by the #:: operator.
What are Tuples in Scala? How can we access the elements of a Tuple?
- A tuple is a collection of heterogeneous elements.
- It can store data of different types.
- It is immutable in nature.
- The type of tuple is defined by the type of elements it has.
- To access the elements of a tuple underscore syntax is used. Eg. tup._1, i._2, etc.
Explain the Syntax for the method definition in Scala
- def keyword to define a method
- name of the method in camel_case
- Method parameters
- The return type of the parameters
- The return type of the method
- Body of the method
What is the tail() method in Scala?
tail() method is just opposite to the head() method. It returns all the elements except the first one.
Define higher-order functions
Higher-order functions take other functions as parameters or return a function as a result.
The map function is one of the most commonly used built-in higher-order functions in Scala.
Define traits in Scala? Give an example.
A trait resembles an interface with a partial implementation. In scala, the trait is a collection of abstract and non-abstract methods.
A trait can have all abstract methods or some abstract and some non-abstract methods.
A variable that is declared in a trait gets internally implemented in the class that implements the trait but if the variable which is declared but not initialized is considered abstract.
What is an Anonymous Function? How to declare one?
An anonymous function is a function that does not have a name. Scala uses a lightweight syntax to declare an anonymous function.
What is the role of Options in Scala? How Options are used in the map's get method?
The option represents optional values. Instances of option are either an instance of Some or None.
The get method of Scala's Map produces Some(value) if a value corresponding to a given key has been found, or None if the given key is not defined in the Map.
How to run a simple Scala program?
1. Compile the code using scalac - scalac Dzone.scala
2. Run the code using scala - scala Dzone
How yield is used with the for loop?
For each iteration of the for loop, yield generates a value which is remembered. When the for loop finishes running, it will return this collection of all the yielded values. The type of the collection that is returned is the same type that you were iterating over i.e. if the iteration is done on a Map, a Map will be returned and if the iteration is done on a List a list will be returned.
Define Nil, None, and Nothing in Scala?
- Nil - It represents an empty list.
- None - Option has exactly 2 subclasses- Some and None. None signifies no result from the method.
- Nothing - It is a Trait. It is a subtype of everything. There are no instances of Nothing.
Where do we get the name Scala?
According to Scala's official documentation:
The name comes from two sources. First, "Scala" is the Italian word for stairway, which is appropriate since Scala helps you ascend to a better programming language. The Scala logo is an abstraction of a stairway. Also, Scala stands for scalable language, because Scala's concepts scale well to large programs.
What is the super class of all classes in Scala?
The superclass of all classes is scala.Any
What is the difference between Function and Method in Scala?
Scala supports both functions and methods. The syntax for a method and a function is identical.
Major difference in the two:
- A method can be defined in a Scala class or trait which means that a method is associated with an object. We can call a method by using an instance of a Class. A method cannot be used directly without an object.
- Functions are defined in a Scala Package. They are not associated with a class or a trait. Just like Java's static methods, they can be called without using an object.
Thanks for reading..... and best of luck for your interviews.
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