If you're looking for Apache Scala Interview Questions & Answers for Experienced or Freshers, you are at the right place. There are a lot of opportunities from many reputed companies in the world. According to research Apache Scala has a market share of about 0.1%. So, You still have the opportunity to move ahead in your career in Apache Scala Engineering. Mindmajix offers Advanced and most asked Apache Scala Interview Questions 2020 to help candidates crack interviews & acquire a dream career as Apache Scala Engineer.
|Types of Scala Interview Questions|
Scala is a general-purpose programming language that supports both functional and object-oriented programming. Its source code is compiled into Java bytecode and executable code runs on Java virtual machine.
There are four types of identifiers are used in Scala -
These are different literals used in scala -
Following are the advantages of Scala -
Scala set is a group of pairwise different elements of the same type. This set contains no duplicate elements. There are two types of sets - mutable and immutable. By default, scala uses immutable sets.
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Scala map is a group of unique value (Key) pairs. Maps are also called as hash tables and they are categorized into two - mutable and immutable. The main difference between mutable and immutable is that an immutable object cannot be changed by itself.
Variables are the reserved memory location used to store values. When you create a variable, based on the data type of the variable, the compiler allocates memory for it. reserved.
A class is a user-defined prototype that contains variables and methods. An object is an instance of a class using which methods and variables can be accessed.
Recursion is a function that calls itself again and again. The last operation performed by this function is to call itself. This technique is used in functional programming.
A trait consists of method and field definitions which can be reused by mixing them into classes. A trait definition looks exactly like a class definition, the only difference is that it uses the word Trait.
Case classes are the regular classes that can export their constructor parameter and allow recursive decomposition via pattern matching. These constructor parameters are considered as public and can be accessed directly.
In order to format a string, we can use .format() method.
Val formatted= “%s %i”.format (mystring.myInt)
Scala prefers immutability by default and helps to deal with concurrent programs and equality issues.
In Scala, we can ":+" single value. Check out the below given example to understand better.
var myList = List.empty[String]
myList :+= "a"
myList :+= "b"
myList :+= "c"
use++ for appending a list
var myList = List.empty[String]
myList ++= List("a", "b", "c")
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In Scala, val defines a constant, a fixed value which cannot be modified once declared and assigned while var defines a variable, which can be modified or reassigned.
No language is perfect, but Scala brings many advantages that make it better than other programming languages. Some of those features are -
Tuples are used to combine a fixed number of items together in a group so that they can be passed as a single item. A tuple is immutable which can hold different types of objects, unlike an array or list.
Currying is a simple process of transforming a function that takes multiple arguments into a function that takes a single argument. This function is commonly used in multiple functional languages.
When no value or parameter is passed to a method or function, then the compiler looks for implicit parameters and executes it further. A method can contain only one implicit keyword.
Scala closures are the functions that use multiple free variables and the return value of the function is dependent on these variables. Free variables are defined outside the closure function and are not bound to a function with a valid value.
Scala high order functions are the functions that contain other functions as parameters and also return a function as an output. In easy words, a function that operates with other functions is called a higher-order functions.
Scala anonymous function is a function that does not contain any name and provides a lightweight function definition. It is useful when a user has to create an inline function.
Some of the most common framework supported by Scala is -
In scala, two types of variables are used most commonly and they are -
Mutable Variables declared using the var keyword.
Values in the Mutable Variables support Changes
Immutable Variables declared using the val keyword.
Values in Immutable Variables do not support changes.
Scala stream is a list that can be infinitely long because its elements are computed lazily.
Operators in Scala are -
Scala offers a helper class called 'App' that contains the main method and its members. Instead of writing your own main method, you can extend the App class and produce executable applications in Scala.
In Scala, we have three types of scopes for variables as follows-
Fields: Fields are the variables declared within an object which can be accessed anywhere in the program depending upon the access modifiers. Fields are declared using var as well as val.
Method Parameters: Method parameters are strictly Immutable. Method parameters are mainly used to Pass values to the methods. These are accessed inside a method, but it is possible to access them from outside the method provided by a Reference.
Local Variables: Local variables are declared inside a method and they are accessible only inside the method. They can be accessed if you return them from the method.
Some of the scenarios where Scala differs from Java are as follows:
Scala treats each and every single value as an object including functions. Hence, scala is a fusion of both functional as well as to object-oriented features.
We have mainly three access modifiers in Scala and they are -
Private: a private member is accessible only in the Class or the Object in which it declared.
Protected: a protected member can be accessed from Subclasses of the class it is declared in.
Public: Public members can be accessed from anywhere.
Yield is used in a loop and produces a value for every iteration.
A Monad is an object that wraps up another object in it. It allows chaining the operations together.
The most common and default Packages in Scala are -
Option in Scala is used to Wrap the Missing value.
First of all, the code is written in Scala REPL or a Scala IDE, then it is converted into a Byte code and sent to the JVM for compilation.
Auxiliary constructor is used for constructor overloading. It calls either the previously defined auxiliary constructor or primary constructors present in the body. A scala class may contain zero or more auxiliary constructors.
An extractor is an object which contains a method 'unapply' as one of its members. unapply method is used to match the values and take them apart.
Scala evaluates y*z first and then adds (y*z) with x.
Like other programming languages, Scala also follows Presidency and Priority table rules.
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