{"id":29284,"date":"2021-02-18T10:52:38","date_gmt":"2021-02-18T18:52:38","guid":{"rendered":"https:\/\/careerkarma.com\/blog\/?p=29284"},"modified":"2022-07-20T08:57:50","modified_gmt":"2022-07-20T15:57:50","slug":"how-to-learn-kotlin","status":"publish","type":"post","link":"https:\/\/careerkarma.com\/blog\/how-to-learn-kotlin\/","title":{"rendered":"Kotlin: Courses, Trainings, and Other Resources"},"content":{"rendered":"\n

Have you ever wondered how Android applications work? How are the apps that help you in your day-to-day activities created? There certainly is a whole ecosystem of frameworks and languages to help create these apps, but which one is recommended by the creators of Android themselves<\/a>? The answer to these questions is Kotlin \u2014 the latest addition to the Android application development frameworks available in the market, and directly backed by Google themselves.<\/p>\n\n\n\n

How to Learn Kotlin<\/h2>\n\n\n\n

Kotlin is a powerful programming language to write mobile applications in, so it is important to understand its purpose and features before we dive into learning its dynamics.<\/p>\n\n\n\n

What is Kotlin?<\/h3>\n\n\n\n

Kotlin is an open-source programming language, specifically designed with mobile application development in mind. It offers a competitive advantage over the traditional language for Android \u2014 Java \u2014 in aspects like code readability and cross-platform application development. Kotlin, outside of mobile application development, is a full-fledged, object-oriented programming language.
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Kotlin is highly recommended by Google due to the number of benefits it offers over Java. Kotlin\u2019s syntax is similar to Python\u2019s, making it simple to learn and use. With the increasing community support, people are writing data analysis libraries in Kotlin, which hints at Kotlin becoming the next big thing in machine learning in the coming times.
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Kotlin also finds use in web application development. The ability to compile Kotlin code to a JavaScript equivalent opens a world of cross-platform possibilities for Kotlin. This means that you only need to write your code once in Kotlin, and you can create working mobile, web, and desktop apps for your product. Before we dive into these use-cases in detail, let us take a moment to understand the advantages of using Kotlin over its counterparts.<\/p>\n\n\n\n

Features of Kotlin<\/h3>\n\n\n\n

Kotlin offers multiple features as a programming language. Here are some of them:<\/p>\n\n\n\n

Concise Code<\/h4>\n\n\n\n

One of the primary reasons why Java is known to have a steep learning curve is the boilerplate that it brings. And when it comes to Android applications, Java adds even more boilerplate code in every project. Kotlin aims to solve this issue with simple syntax and easy to understand notations.
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A glimpse of this can be seen by comparing the traditional \u201cHello World\u201d program in the two languages:
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Java:<\/p>\n\n\n\n

class Test {\n    public static void main {\n         System.out.println("Hello World!");\n    }\n}<\/pre><\/div>\n\n\n\n
Kotlin:<\/p>\n\n\n\n
fun main() {\n    println("Hello World!")\n}<\/pre><\/div>\n\n\n\n
Kotlin takes away the load of always declaring a class to write code, by taking the main function to the top-most level. It also simplifies the print call, and this is a fair representation of other simplifications implemented throughout the language.<\/p>\n\n\n\n
Improved Null Safety<\/h4>\n\n\n\n
Null pointers are one of the most common issues faced by Java developers. They take up a lot of time and cause unneeded frustration. In many cases, this happens due to a reference variable not being checked for null before being accessed.
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In Java, this is traditionally done by putting an if case before accessing the variable, like this:
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\/\/ let foo be a variable\n\nif (foo != null) {\n    foo.bar();\n}<\/pre><\/div>\n\n\n\n
This code can cause errors in the application if missed out. Kotlin nicely addresses this issue, and the Kotlin compiler by default does not allow any variables to have a value of null at compile time. So if you are missing a null check somewhere in your app, or operating on a null variable, you will be notified at the compiler time itself.
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This does not let null-pointer bugs reach the final application. Alternatively, you can implement safe method calls for yourself. If you were to write the above piece of code with Kotlin\u2019s safe call, this is how it would look:<\/p>\n\n\n\n
\/\/ let foo be a variable\nfoo?.bar()<\/pre><\/div>\n\n\n\n
This code will call the bar method on the foo object if foo is not null, or return null if foo is null. This lets you easily make complex, chained calls like these:<\/p>\n\n\n\n
baz?.foo?.bar()<\/pre><\/div>\n\n\n\n
Interoperability with Java<\/h4>\n\n\n\n
Kotlin compiles to Java bytecode by default. This makes it simple to use precompiled Java classes with Kotlin code. You can write an application using Java as well as Kotlin, and it will all compile to Java bytecode, which will be able to interoperate within the Kotlin and Java parts freely. This makes the migration of huge, legacy Java applications to Kotlins smooth, as not all code needs to be migrated at once.
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Apart from that, smart IDEs like the Android Studio are capable enough of converting Java source code into Kotlin on the fly. This means you can simply convert your old Java classes into Kotlin classes using nothing more than your IDE.<\/p>\n\n\n\n
Converting (Transpiling) to JavaScript<\/h4>\n\n\n\n
Kotlin also offers you the option of transpiling your code to JavaScript. Transpilation simply means converting a source code written in one language to that written in another. Kotlin allows you to write apps that can run on web and desktop platforms.
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According to the current official documentation, the current version of Kotlin targets ES5.1 for JavaScript environments, which means that it can not benefit from some of the major improvements that were shipped with ES6. Also, it currently supports converting only Kotlin code to JavaScript equivalent, and anything present in a project that is not written in Kotlin does not get transpiled to JavaScript. This leaves a lot of room for improvement.<\/p>\n\n\n\n
Native Conversion with Kotlin Native<\/h4>\n\n\n\n
Applications written in Java-based languages require a virtual machine to run. All Java applications require a Java Virtual Machine (JVM) to be installed on the target host. While the current version of Kotlin requires the same too, a technology called Kotlin Native is being developed to free the applications of this restriction.
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Kotlin Native aims at compiling code to native executables, rather than bytecode. These executables can then be run without a virtual machine. This improves performance as the system does not need to run a virtual machine to execute a Kotlin application.<\/p>\n\n\n\n
What is Kotlin Used for?<\/h3>\n\n\n\n
Kotlin is growing as the primary language for native Android application development. Before we set down to learn the library, let’s explore some of its main use cases:<\/p>\n\n\n\n
For Creating Mobile Applications<\/h4>\n\n\n\n
Java was the traditional language for writing mobile applications before Kotlin because the Android framework supported a JVM (Java Virtual Machine) for natively running applications. However, writing code in Java is not the best experience for developers and the Android framework adds more boilerplate to projects.
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The primary reason why Kotlin was created was to easily write native Android applications. Kotlin does this job well by simplifying the traditional Java syntax, as well as reducing the usual boilerplate in Java.<\/p>\n\n\n\n
For Building Backends<\/h4>\n\n\n\n
Kotlin is growing as a strong alternative for server-side development. As mentioned previously, Kotlin works in all those cases where Java would normally work, as both languages compile down to similar bytecode executables, and require the same JVM to execute their binaries.
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Additionally, Java libraries can directly be used in Kotlin, so you can interchange your source code\u2019s languages to get the best out of both. The libraries that are not yet written in Kotlin can be used directly via their Java bytecode, and the features of Kotlin can be used to simplify the business logic written in the application.<\/p>\n\n\n\n
For Creating Frontends<\/h4>\n\n\n\n
Kotlin supports transpilation to JavaScript, and this ability also allows writing applications that can run on web browsers. The Kotlin\/JS module facilitates this feature. It provides an interface via the kotlin.js plugin. This simplifies the process of setting up Kotlin projects that aim to build front-end applications in JavaScript.
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Using Kotlin, type-safe React applications can be written quite easily. JavaScript technologies like react-redux, react-router and styled-components are supported with Kotlin\/JS, and you can easily use them together with other libraries to build your components and libraries.<\/p>\n\n\n\n
For writing Gradle plugins<\/h4>\n\n\n\n
A Gradle plugin is a piece of code that defines a part of your build logic, i.e. it allows you to define how your Gradle-based project will be built into a final executable. Gradle plugins can be written in any language that compiles down to JVM bytecode.
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Groovy has been the traditional choice for writing Gradle plugins, after Java. Since Kotlin compiles down to JVM bytecode as well, it can be used to write a Gradle plugin. Kotlin provides additional benefits over Groovy like type-safe and concise code.<\/p>\n\n\n\n
Learning Kotlin<\/h2>\n\n\n\n
Given that Kotlin is an advanced programming language with diverse uses, there is plenty to learn. Following is a list of resources to help you get started:<\/p>\n\n\n\n
The Best Kotlin Resources<\/h3>\n\n\n\n
As Kotlin is an open-source programming language, people have tried to create content that can help you easily get started with it. First of all, let\u2019s take a look at the free and paid video courses that are available for Kotlin:<\/p>\n\n\n\n
Training Courses<\/a> by Android Developers<\/h4>\n\n\n\n