Kotlin Interview Questions

In this article, we will discuss top Kotlin Interview Questions in most simplified ways with examples.

Introduction

In this article, we will discuss the Kotlin Interview Questions

According to PYPL(Popularity of Programming Language), in 2022 Kotlin is among the top 10 programming languages. It is officially supported by Google. Kotlin is the future of android app development. It has more than 8M of lines of code on GitHub with more than 165 thousand repositories.

Table of Content

1. What is Kotlin?
2. What are the main features of Kotlin?
3. What are the different data types in Kotlin?
4. What are the variables in Kotlin?
5. What is the difference between Var and Val?
6. What are Data Classes in Kotlin?
7. What are the different operators in Kotlin?
8. What are the different functions in Kotlin?
9. What are the different types of Constructors available in Kotlin?
10. What is the difference between Kotlin and Java?
11. Why should we use Kotlin?
12. Does Kotlin allows to use primitive type such as int, double and float?

Top 10 Basic Kotlin Interview Questions

Q1. What is Kotlin?

A1. Kotlin is a cross-platform, statically typed, general-purpose programming language. It is a language for Java Virtual Machine. 

Kotlin is used in server, client, web and android development. It suits multi-platform development and allows writing fewer codes.

Some of the top companies like Pinterest, Coursera, basecamp etc. use Kotlin.

Click Here: Kotlin Bootcamp for Programmers

Q2. What are the main features of Kotlin?

A2. Kotlin has some advanced features for web and android development like

• Clean, compact Syntax
• Efficiency
• Extension Function
• Interoperability with Java
• Reducing crashes at run-time

Q3. What are the different data types in Kotlin?

A3. In Kotlin, everything is an object in the sense that we can call member functions and properties on any variable:

Data Type in Kotlin:

• Numbers
  • Integer
    • Byte
    • Short
    • Int
    • Long
  • Floating
    • Float
    • Double
• Boolean

Boolean represent boolean objects that can have only 2 values: TRUE and FALSE.

Built-in operation on boolean includes:

• && – conjunction (logical AND)
• || – disjunction (logical OR)
• ! – Negation (logical NOT)

• Characters

Characters in Kotlin are represented by Char and are used to store single characters. The value of the char must be surrounded by single inverted commas.

• String

Strings are the sequence of characters in double quotes. String in Kotlin is represented by a String. Elements are accessed by indexing operations. A string is immutable in nature. String values must be double-quoted.

• Arrays

It is used to store multiple-value into a single variable. They are represented by the Array class. An array is invariant, which prevents possible run-time failure.

Q4. What are the variables in Kotlin?

A4. Variables are used to store the data, it refers to a memory location. To declare a variable in Kotlin, either the var or val keyword is used.

var name = “Shiksha Online”

val employee = 50

The main advantage of Kotlin over other programming languages is that it does not need to be declared with a specified type. It is smart enough to understand the string or int variable.

Q5. What is the difference between Var and Val?

A5. Val: Val is immutable i.e. we can’t change the value of a variable once it is assigned.

var name = “Shiksha Online”

name = “Naukri” // error

Var: Var is mutable in nature i.e. the value of the variables can be changed after assigning too.

var employee = “50”

employee = 15 // execute

Q6. What are Data Classes in Kotlin?

A6. The main purpose of the data classes is to hold the data. In kotlin, data classes are marked with data

Requirements to create data classes:

• The primary constructor should have at least one parameter
• Parameters of the Primary constructor should be marked as var or val
• Data classes can’t be abstract, inner, open or sealed.

The compiler automatically derives the following member from the properties declared in the primary constructor:

• equal()
• hashcode()
• tostring()
• componentN()
• Copy

Q7. What are the different operators in Kotlin?

A7.  In a programming language, operators are the symbols that are used to perform specific mathematical and logical manipulations.

Similar to other programming languages, Kotlin has different operators:

• Arithmetic
• Relational
• Assignment
• Unary 
• Bitwise
• Logical

Q8. What are the different functions in Kotlin?

A8. The function is a set of codes that are used to perform a special task. You can pass data, into a function. Kotlin functions are declared using the fun keyword.

Depending upon whether a function is defined or inbuilt, Kotlin has two types of functions:

Standard Library Function

Kotlin has lots of builtin function, here are some of them:

• arrayOf()
• sum()
• printIn()
• sqrt()
• rem()
• compareTo()

User-defined Function

Q9. What are the different types of Constructors available in Kotlin?

A9. Constructors are special member function that is called when an object is created. It is a concise way to initialize class properties.

There are two types of constructors are available in Kotlin:

Primary: 

• It is used to initialize the class and declared it in the class header after the class name.
• Declared using constructor Keyword
• Codes are surrounded by parentheses with optional parameters

Secondary: 

• In Kotlin, a class can contain more than one secondary constructor
• There are not common in Kotlin.
• Secondary constructors are created using the “constructor” keyword.

Q10. What is the difference between Kotlin and Java?

Features	Java	Kotlin
Object-oriented programming	Not pure OOP	Fully OOP
Extension Functions	No	Yes
Inline Functions	No	Yes
NullPointer Exceptions	Yes	No
Lambda Expression	No	Yes
Invariant Array	No	Yes
Non-private Fields	Yes	No
Singletons Objects	Yes	Yes
Static Members	Yes	No

Click Here: Kotlin vs Java: Why You Should Choose Kotlin Over Java

Q11. Why should we use Kotlin?

A11. Kotlin is concise, null-safe and interoperable.

Q12. Does Kotlin allows to use primitive types such as int, double, float?

A12. No, Kotlin does not allow to use primitive types directly. We can use the class like int, double, float as an object wrapper for primitive but the compiled bytecode has these primitives.

Conclusion

In this article, we have discussed Kotlin Interview Questions in most simplified ways with example.

Hope this article will help you to ace Kotlin interview.

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