Programming languages going obsolete and getting replaced by newer and better ones is not anything new. In the last decade, we have witnessed the emergence of several programming languages that have garnered significant popularity. One particular name that has been in the limelight for obviously good reasons is Kotlin.
Developed by Czech software development giant JetBrains, Kotlin was introduced to the world for the first time in 2011. It is a general-purpose programming language statically typed and works well on various platforms, including Android, iOS, Windows, macOS, and Linux.
If you are thinking of choosing Kotlin as your primary programming language, especially for Android development, we must say that you are on the right track. Why? Because Google itself declared Kotlin as the preferred programming language for Android app development back in 2024.
Before you jump to the conclusion that Kotlin is suitable for Android development only, we just want to make it clear that it is also remarkably known for its capabilities as a server-side scripting language.
Nonetheless, if you want to learn Kotlin quickly and effectively so that you can make a career in software or web development, you have landed just at the right place. In this detailed Kotlin learning guide, we will provide you with almost everything you need to get started on your way to becoming a master Kotlin developer. So, let’s get started!
Why Should You Learn Kotlin?
It might be the very first question resonating in your mind when thinking about learning Kotlin. Well, there is more than one reason that reinforces the idea of learning and moving forward in your career with Kotlin.
The demand for Kotlin among developers is increasing day by day. Also, Kotlin is well-known for making it possible to develop cross-platform apps quickly. Several advantages like these make Kotlin one of the best modern programming languages to learn today.
Before discussing the best reasons to learn Kotlin, it is important to understand that, like every other programming language out there, Kotlin also has some shortcomings, such as inconsistent compilation speed and limited learning resources compared to other programming languages. However, to be honest, the pros of Kotlin easily outweigh its cons.
Now, let’s take a look at the most common reasons why many individuals prefer working with Kotlin:
Modern and Powerful
If you consider the most popular programming languages, you will notice that most are quite old. While they have evolved by adding advanced features and capabilities, they can still not be fully compared with a modern programming language like Kotlin.
Kotlin is an innovative programming language, brings together all the finest traits of object-oriented, statically-typed, functional, imperative, and declarative programming paradigms to deliver next-level application and web development experience.
It is a feature-rich and secure general-purpose programming language that allows you to write clean code concisely. Thus, making Kotlin one of the most powerful programming languages out there.
Easy to Learn
As a beginner, you may wonder if you’ll be able to learn Kotlin without facing any significant challenges. Despite being a powerful programming language with many advanced features, it is easy to learn, thanks to its straightforward syntax. Even if you want to enter into the world of coding with Kotlin as your first programming language, you can do that with fair ease.
Also, you will be able to learn Kotlin more quickly if you have experience working with Java or Python. Those inspire several concepts in Kotlin in Java and Python. So understanding these two leading programming languages will boost the process to develop a solid understanding of the Kotlin fundamentals.
Interoperable with Java
It is yet another outstanding feature of Kotlin that makes it a great choice for Java developers. Kotlin is completely interoperable with Java, which means you can use it literally in almost all Java-based applications. Moreover, it is also relatively easy to integrate Java applications to Kotlin, and you can use both the programming languages simultaneously in a single application.
You can consider Kotlin as an enhanced version of Java, and thus shifting to Kotlin would be a great move for Java developers. Moreover, by using Kotlin, it is possible to improve the functionality and performance of Java-based apps.
Supported by Google for Android Development
As we have told you earlier, Kotlin has been Google's preferred programming language for developing Android apps since 2019. However, you’ll be even glad to know that Google had offered its first-class support to Kotlin way back in 2017. Being supported by a tech giant like Google is a clear indication of the potential that Kotlin has.
So, if you are particularly interested in Android development, you need no further than Kotlin. Also, all the latest releases of Android Studio come with Kotlin support. You can create projects that use Kotlin, debug Kotlin code, and even convert Java code into Kotlin code with relative ease. Moreover, developing Android apps with Kotlin requires less time than Java, which is also a huge plus.
High in Demand
The following reason for you to learn and master Kotlin resonates with the fact that Kotlin developers are in high demand in the market. If you scrutinize the IT industry, you will find that several tech companies are leveraging Kotlin to develop high-end applications that can meet their demands effectively.
As Kotlin can be used for developing cross-platform apps and works extremely well in back-end development, companies are actively looking for individuals who are comfortable working with Kotlin. It eventually drives the opportunities in the market, and also, the pay scale offered to Kotlin developers is quite impressive.
So, if you master Kotlin, you are likely to build a prosperous career as you will be able to work in some of the most reputable companies in the world.
Multiplatform and Extremely Flexible
Talking about the multiplatform nature of Kotlin, you can run Kotlin code on almost all the popular platforms such as Windows, macOS, Android, and iOS. Kotlin has become a weapon of choice for many developers who want to create cross-platform mobile applications.
You can create and used business logic across different platforms without any issues. Also, as we have mentioned earlier, Kotlin gives you the flexibility to use it for developing high-performance web apps.
One thing that you need to note is that the multiplatform capability of Kotlin is still in its initial stages. However, it is quite easy to anticipate that Kotlin will become more powerful with upcoming releases.
Extensive Community Support
The widespread adoption of a programming language is considerably dependent on its community. When we talk about Kotlin, it also has a large community that works to better the programming language. It helps developers with their everyday issues regarding the usage of Kotlin. Developers can put forward ideas to improve its functionality since it is an open-source programming language.
According to JetBrains, there are approximately 200 Kotlin user groups and numerous online forums where Kotlin enthusiasts can discuss ideas and help each other. Also, more than 450 developers are contributing directly to improve the overall ecosystem of Kotlin. Having such an extensive community that is highly active makes Kotlin stand out firmly among the most valuable programming languages of the 21st century.
Now, if you are motivated enough to get going on your journey to learn and master Kotlin, it’s time to take a leap forward and discuss everything important that will help you learn Kotlin comprehensively.
Prerequisites for Learning Kotlin
Kotlin is a beginner-friendly language, and you can learn it even if you have little to no prior knowledge of programming. However, anyone having experience working with Python or Java will be able to master Kotlin quickly. Java highly inspires Kotlin; thus, switching to Kotlin will likely be a cakewalk if you are a Java developer.
Nonetheless, if you are a complete beginner, ensure to meet the following prerequisites to learn Kotlin efficiently:
- Basic knowledge of computers and their functionality.
- Ability to install and manage multiple software on a computer system.
- Familiarity with Android and iOS (for mobile app development).
- Basic understanding of web development, especially back-end development.
Now, if you are ready to move forward with your endeavour of learning Kotlin, you may need to get yourself familiar with an IDE that will make it convenient for you to write code and manage Kotlin projects with ease.
Usually, the simplest way to start writing code is by making use of a source code editor. If you are unfamiliar with a source-code editor, we must tell you that it is a text editor with specialized features that allows you to read, write, and edit code productively.
Now, you can consider an Integrated Development Environment as a superior choice to source code editors. In general, an IDE brings together several tools that’ll assist you with creating applications and lets you test and deploy them.
An IDE will provide you with an in-built source-code editor, a debugger, a compiler, and various advanced features, such as syntax highlighting auto code completion and code refactoring.
When working with Kotlin, choosing an IDE over a source-code editor is a better option because the former will make it much easier for you to maintain complete control over your projects. Moreover, several big firms prefer IDEs to develop and manage their Kotlin projects. Here is our pick of the three top-rated IDEs that are ideal for working with Kotlin:
IntelliJ IDEA is the best Kotlin IDE available out there, and there’s a notable reason for this. Jet Brains, which is the company behind the creation of Kotlin, is also the developer of IntelliJ IDEA.So, you could easily guess how smoothly this IDE can work with Kotlin.
Interestingly, IntelliJ IDEA is a dedicated IDE for Java. Nonetheless, it works equally well for Kotlin and has several features capable of accelerating the development process.
- Intuitive user interface that is easy to understand.
- Smart code completion enables you to write code faster.
- Code refactoring and detection of duplicate code help you to make your code readable and easy to maintain.
- Inline debugging makes the process of debugging fast and efficient.
- Access terminal and database tools and operate major version control systems like Git, Mercurial, and SVN within the IDE’s interface.
- It offers a free and open-source community edition suitable for individuals and small teams.
Another exceptional choice that you have for working with the Kotlin programming language is Eclipse IDE. This IDE was released for the first time in 2001 and was developed by the Eclipse Foundation.
- It supports coding shortcuts to speed up the development.
- The auto-correction feature helps you to keep your code error-free.
- You can use code refactoring and one-click source code formatting to ensure superior readability.
- Offers Kotlin compiler and Kotlin builder to track changes and compile Kotlin files with ease.
- You’ll be able to access several advanced features like code completion, debugging, and linting.
- Allows you to integrate several third-party plugins to expand the overall functionality.
- The IDE is available as open-source software that is free to use under the Eclipse Public License 2.0.
While both the IDEs mentioned earlier need to be installed on your system, the Kotlin IDE offered by Coding Rooms works completely online. This cloud-based IDE is an apt choice for you if you want to bypass the process of downloading and set up an IDE locally on your system. Also, this IDE allows you to write, compile, share, and collaborate on Kotin code.
Being available online doesn’t mean that this IDE isn’t powerful; you can create and manage complex projects. Also, the best thing about this IDE is that you can write Kotlin code without any signup.
- Simple and easy-to-use interface.
- It allows real-time collaboration on projects.
- You can test and run Kotlin code in your private workspace.
- It offers a free version.
How to Learn Kotlin? [A Step by Step Guide]
Today, it’s quite easy to get access to a wide range of resources that can help you learn Kotlin. The web is full of guides, tutorials, etc., that will help you get familiar and even build expertise in Kotlin development. Nowadays, comprehensive tutorials have become the first choice for learners. Thus, you can also consider a popular Kotlin tutorial to get started on your journey of becoming an expert Kotlin developer.
However, when you search the internet for Kotlin tutorials, you will likely get overwhelmed by the sheer number of tutorials available over there. Doing comprehensive research to find the most valuable and effective tutorials would consume a lot of your time.
To help you out, we have simply cherrypicked the best online Kotlin tutorials that have successfully gained positive responses from a large number of learners. Also, we will give a brief overview of each tutorial so that it may become easier for you to decide which one to choose.
5 Top Kotlin Tutorials
Here are the five best tutorials that offer great value when it comes to learning Kotlin effectively:
It is a full-length course available on Udemy that consists of several video tutorials. It majorly focuses on the Kotlin concepts used in Android development, and thus, it is an apt course for anyone interested in becoming an Android developer. Dr Hussein Alrubaye is the creator of this course, and he currently works at Microsoft as a senior software engineer.
The tutorial is explicitly curated here for individuals new to Kotlin and with almost zero prior knowledge of Android app development. Also, this tutorial is among the top-rated tutorials available on Udemy, with more than 145K students enrolled for it.
- Average rating of 4.2 stars out of 5.
- Suitable for beginners.
- It is divided into 23 sections that have a collective completion time of approximately 27 hours.
- Include development of various projects, including online games and Android apps.
You can signup here.
Udacity is a well-known online learning platform that helps individuals to learn and develop new skills. The Kotlin tutorial offered by Udacity is ranked among the most trusted tutorials available online to get onto the path of becoming a Kotlin expert. The instructors for this tutorial are Aleks Haecky and Asser Samak. Both are professional Kotlin developers.
The estimated duration of this course is two weeks, and the ideal skill level is intermediate. It means that your learning experience would be best if you have at least some knowledge of programming in general and familiarity with the basic OOP (object-oriented programming) concepts. The Kotlin course will guide you in Kotlin fundamentals, the concept of classes and use of OOP in Kotlin, the importance of functions, and functional manipulation.
- Short video lectures facilitate productive learning.
- It comes with interactive quizzes to test your knowledge.
- Concepts are taught with examples to ensure that you understand how things work.
- It is divided into six distinct lessons to streamline the learning process.
You can signup here.
It is yet another remarkable online tutorial that will help you get familiar with Kotlin. At the end of this tutorial, you will be able to use various concepts of Kotlin to create fully functional applications.
While the tutorial is created by Matt Greencroft, a big data expert, it is made available to individuals by Manning Publications. However, you need to note that this tutorial is ideal for individuals who already have some working experience with Java, though no prior knowledge of Kotlin is required.
Talking about what this tutorial offers will help you understand topics like strings, variables, nullable variables, functions, classes, collection, and looping. Also, you will get to know how the Java-Kotlin interoperability works. In all, this tutorial attempts to cover almost everything important for you to build a solid foundation for becoming a skilled Kotlin developer.
- The whole course is divided into 20 modules, with each module having multiple short-length video lessons.
- You will be able to write meaningful Kotlin code as you will learn concepts with practical exercises.
- You will be using Kotlin alongside the Hibernate framework of Spring Boot and Thymeleaf template engine.
You can signup here.
If you are looking to learn the fundamentals of Kotlin and jump straight into Android app development, this Kotlin tutorial can be a great choice. While the desired skill level for this tutorial is intermediate, you can completely trust it for a fruitful learning experience even if you are a newbie developer.
Your instructor for this tutorial will be Ben Deitch, a professional Android developer and one of the highly ranked teachers at Treehouse. The whole tutorial is divided into four modules to ensure that you learn and grasp concepts well. You will get access to video lessons for learning various topics and quizzes to assess your knowledge.
- You can view video lessons online and also download them on your device to watch them offline.
- You will develop a solitaire game application that is purely written in Kotlin.
You can signup here.
If you can read lengthy write-ups without getting too bored, you can go with this tutorial on the leading online publishing platform - Medium. Even if you favor reading text to learn Kotlin, you should check out how the author has managed to divide the whole tutorial into several parts rather than discussing everything in a single post.
To be precise, there are 11 parts of this tutorial, excluding the introduction and the conclusion parts. Also, this tutorial helps you learn Kotlin concepts by developing an Android app using Android Studio.
If you want to learn Kotlin exclusively for web development, this may not be the tutorial you should opt for. Nonetheless, the topics covered in this tutorial include data classes, functions, and Lambda expressions. Also, the app you will be developing is inspired by Reddit, and you will be dealing with the process of rendering data from Reddit’s public API.
- All the Kotlin concepts are clearly expressed, which ensures a productive learning experience.
- Snapshots and code snippets ensure a firm understanding of the topics under discussion.
- The content of the tutorial is crafted by an experienced Android developer - Juan Ignacio Saravia.
You can signup here.
If you have a tight budget or simply do not want to spend money on buying a Kotlin tutorial, you need not worry, as there are numerous free tutorials available online. However, not every free tutorial is good enough to help you out with learning Kotlin effectively. The most common reason for most free tutorials to be ineffective is that they are loosely structured.
Nonetheless, this particular Kotlin tutorial available on YouTube is completely free and offers an exceptional learning experience. Let us see some free tutorials:
This is a YouTube playlist containing several video lessons on the Kotlin programming language. The tutorial covers all the fundamentals of Kotlin that you need to get familiar with if you want to pursue a career in Android development. There are a total of 64 videos in this tutorial that will help you learn various Kotlin concepts systematically.
For learning Kotlin with this tutorial, you need not have any prior knowledge of Kotlin as it is fully designed for beginners. Through this tutorial, you will understand various concepts such as variables and data types, functions, classes, string interpolation, loops, and primary and secondary constructors. Moreover, you’ll get exposure to functional programming that is essential for building high-performance applications.
- The tutorial covers nearly all the basics of Kotlin.
- It discusses Kotlin-Java interoperability.
- It is one of the most popular Kotlin tutorials on YouTube, with more than 1.6 million views at writing.
If you are interested in developing an in-depth knowledge of Kotlin, the best bet for you is to leverage the official Kotlin documentation. The documentation will come in handy for learning Kotlin from the start and help you develop a solid understanding of its advanced concepts.
Also, whenever a new Kotlin release is out with some new features, the first place you’ll be able to learn about the same is the official docs. Check out the official Kotlin documentation here.
Like every other programming language, you need to work on relevant and challenging projects to strengthen your understanding of various concepts and become efficient in writing Kotlin code.
After learning Kotlin fundamentals from a tutorial, ensure that you use them practically so that they don't get erased from your brain after some time. While some tutorials may guide you to work with multiple projects while learning Kotlin, it is always better to take up some projects completely on your own to hone your development skills.
If you are thinking to get yourself involved in developing some Kotlin projects, here are some project ideas that you will find useful:
A Simple Calculator Application
If you are interested in developing Android apps, then this project would be a great pick for you to put the knowledge of several Kotlin concepts into practice. While developing a simple calculator application is quite easy, it can help you polish your understanding of Kotlin fundamentals.
The calculator app you need to build simply allows users to enter two different numbers and then apply a mathematical operation by clicking on one of the four buttons for addition, subtraction, multiplication, and division. The challenging part of this project would be to design the application’s front-end and place all the elements neat and organized.
Suppose you want to make this project challenging. In that case, you can add numeric keys to your calculator app and enhance the app’s functionality by introducing advanced arithmetic operations like square root and logarithmic functions.
An App Login Page
It is another beginner-friendly Kotlin project that you can develop easily after developing a fair understanding of the Kotlin basics. The login page you need to develop is pretty much the same as that of other apps you use almost every day.
First, a user needs to be directed to a signup page, which requires basic user information like name and phone number. Also, users would need to provide their email addresses and choose a password that will let them log in securely.
The login page would be quite simple with two input fields: the registered email address and the password. Also, there needs to be a login button, which users will have to click after entering the credentials in the input fields. Additionally, you can provide two links on the login page, with one link allowing users to create a new account/sign up and the other link for changing their account’s password.
A Basic To-Do List Application
Building a to-do list application requires you to go beyond the basic Kotlin concepts. It is an intermediate-level project that you should develop after working on some basic Kotlin projects. Although you need to develop a basic to-do list application, you have to make a significant effort to ensure that the app works smoothly without breaking down.
The to-do app you need to develop should allow users to add various tasks to a list. Also, a reminder feature needs to be there, which will help users be reminded about the functions so that each task can be accomplished on time. You can also add a feature that allows users to mark a task as complete.
You can either program the to-do application to store all the tasks-related data on the local device or use a cloud database to access their tasks from different devices.
Tic Tac Toe Game
If you want to advance your Kotlin development skills, you need to get your hands dirty working on a project like the Tic Tac Toe game. While this game is extremely easy to play, developing its application is quite challenging for entry-level developers. The concept of this game is known to many and is straightforward. It is a game that requires the involvement of 2 players at a time, with players choosing the ’X’ and ‘O’ symbols.
Both players act turn by turn to put their symbol in one of the nine boxes. The first player to arrange their symbol three times in a horizontal, vertical, or diagonal line will win the game. However, if none of the players can achieve that before all the boxes are filled with ‘X’ and ‘O’ symbols, the game will result in a tie.
There will be a lot to do both on this game application’s front-end and back-end sides. You get to design the interface thoughtfully and place elements to make the game board and information easily visible to players. You can also add a reset button to allow players to restart the game with ease.
These are a few of the popular Kotlin project ideas that one can develop. You can also search for more Kotlin projects on the web and choose those that seem interesting to you.
To get your dream job as a Kotlin developer, ensure that both your knowledge and practical experience are visible to recruiters. To make that happen, Kotlin certification on your resume is what you need.
Let us help you understand by giving you a clear idea of what Kotlin certification is all about. A certification is a learning program, just like a tutorial or a course. Still, it also offers you a certificate of completion that attests to your skills and achievements during the learning phase.
A certificate is issued in your name when you complete the Kotlin certification program successfully. It highlights whatever you have learned and also certifies that you have a sufficient understanding of a subject (which, in this case, is Kotlin) to work in a professional environment.
The most prominent advantage of having a certification in your resume is that it’ll help you stand out. Usually, recruiters prefer candidates who have enrolled themselves in a certification program and accomplished it. So, a certification will come in handy for you to make it to the interview round.
For Kotlin, there are several reliable certification programs available online that you can take part in and that too from the comfort of your home. But before you rush, you need to keep in mind that you need to pay a certain fee for enrolling in most certification programs. Here are some of the best Kotlin certifications:
- Kotlin for Java Developers - Offered by Coursera
- Android App Development Masterclass using Kotlin - Offered by Udemy
- Kotlin Training - Offered by MindMajix
Kotlin Interview Questions
Interviews are challenging as your technical knowledge and skills are put under test to assess if you are the right fit for the job role. Also, it’s true that your personality and soft skills also matter significantly for cracking an interview, but let’s keep them aside and focus on the technical aspects.
While appearing in the interview for the Kotlin Android developer role, you may be asked several technical questions that may range from basic to advanced level. So, you better be prepared for them, and the best way to do so is to get familiar with the most frequently asked Android interview questions like the ones below:
- Explain the build process in Android.
- List some languages that can be used to program in Android.
- What is the purpose of Companion Objects in Kotlin?
- Explain the difference between safe calls and null checks.
- Describe Folder, File & Description of Android Applications
- What are ‘activities’? Describe the lifecycle of an activity.
- What do you understand about the Elvis operator in Kotlin?
- Explain the Null Safety in Kotlin.
- Explain the dialogue boxes supported on Android.
- What are some of the disadvantages of Android?
If you want to check out more questions like these along with their answers, you can check out our top Android interview questions blog.
To Wrap it Up
Kotlin is undoubtedly a programming language created with a focus to meet the demands of today. However, it’s always the best move to first make it clear in your head as to why you should learn the modern programming language and if it’s going to help you achieve milestones that you aim for.
There are numerous reasons for learning Kotlin, and we have discussed the most popular ones above. Also, we highlighted the prerequisites for learning Kotlin along with the best IDEs that will come in handy for you to write Kotlin code and manage your project efficiently.
To learn Kotlin to use it professionally for Android and web development, you can take guidance from one or more extensive tutorials. Also, you can go with a certification program to learn Kotlin and, at the same time, earn a certificate that testifies your achievements.
The demand for Kotlin developers is increasing in the market. If you want to land a well-paying Kotlin developer job, make sure that recruiters can notice your skills. You can work on multiple Kotlin projects to hone your skills and add them to your resume achievements. Also, you need to prepare yourself for interviews, and getting familiar with the frequently asked interview questions is a great way to get started.
All in all, you can become a proficient Kotlin developer if you know the right path to learn and master Kotlin, and this detailed guide aims to guide you through that path. If you have found this helpful write-up, you can share it with anyone who you think can benefit from it too.
Good luck! âœŒ
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