Kotlin: An Introduction

In Google I/O 2017, Kotlin was announced as an officially supported language for android development. The news created a massive buzz among the developers community. Google is a big name and so is Android. So that level of attention was only natural. But many of those who have followed the language since it’s inception, didn’t need to wait this long to fall in love with the language. Kotlin is a brilliant language. It’s statically typed yet quite productive. The syntax does not feel rigid or restrictive, rather it feels rather expressive and enjoyable. Writing code in Kotlin is really fun. You don’t have to trust my word for that, just give it a try.

History of Kotlin

In case you didn’t know, Kotlin is named after the Kotlin Island near Saint Petersburg, Russia. You can read more about the Island in Wikipedia. So another programming language named after an Island, but why? Well, Kotlin is developed by those awesome guys at Jetbrains  who build our favorite IDEs. Apparently Kotlin was developed in their Saint Petersburg office and the developers named it after the Island.

Jetbrains was using Java to build their IDEs but why did they decide to create a language of their own? The answer is probably obvious to you by now. Every new language is created out of frustration from the existing ones. We already saw a similar story in our post about Golang. The same thing happened here too. Jetbrains lead Dmitry Jemerov mentioned they were looking for features not offered by Java or most other languages. They liked Scala but the compile time was a bugger. So they came up with Kotlin and thanks to them that they did!

Work on Kotlin started in 2010 and Jetbrains announced the language publicly in July 2011. They made the project open source under the Apache 2 License in 2012. They continued developing the language by accepting and reviewing user’s feedback. After a lot of improvements and iteration, the language reached version 1.0 in February 2016, the first officially stable release with commitment towards backward compatibility. That was just a year go. Kotlin became quickly popular and developers seemed to love it. Many large companies started adopting it even before it became officially supported on Android. But the official support didn’t take long either, in Google I/O 2017, first class support came for Kotlin on Android.

Write once, Run Everywhere

Do you recognize the words – “Write once, run anywhere / everywhere”? If you’re a Java developer, you might recognize them. Kotlin takes things a little bit further than that. Kotlin started off as a language based on the JVM. You could run Kotlin anywhere you could run Java. But that’s not all, Kotlin code now can be transpiled into Javascript too! You already know it works on Android. The guys are also working on a native version based on LLVM. Once that happens, you can truly write code once and run them anywhere and everywhere. Of course you can’t fully port all codes from one platform to another, for example if you’re using JavaFX on the JVM, those will not work on the browser. But the common business logic can be ported without much efforts in most cases.

Kotlin is fully interoperable with Java and can take advantage of the JVM. So the plethora of existing Java libraries and packages are at your disposal. This opens up enormous possibilities and a large eco system to the enterprising Kotlin developer.

Most Loved Kotlin Features

So what makes Kotlin great? Why do people love it? Here are some of the features people love in the language:

  • Full interoperability with Java (and the JVM)
  • Multi platform – JVM, Android, Browser and Native (coming soon)
  • The syntax is quite similar to other popular programming languages. Expressive and productive.
  • Type inference is another cool feature. You can just write val number = 23 and it an identify that it’s an Int. You can of course declare the type if you wish 🙂
  • The when block can cut the need of complex if/else block or switch statements and makes things simpler.
  • Libraries like Anko not only makes android development faster, it also makes if more enjoyable. Also the android extensions for Kotlin makes many pain points easier to handle.
  • Functions are fun, literally 😉 fun meaningOfLife() = 42 – see? fun – it is! 😀
  • Simple one line functions paired with string interpolation is pretty useful – fun fullName() = "${first} ${last}"
  • The idea of data class is to provide easy POJOs in a very short, concise manner.
  • Operator overloading is quite simple.
  • You can add extension functions to classes, even built in ones, easily extending their functionality.
  • Kotlin provides null safety by forcing you to check nullable types for null first. No more NullPointerException for you! 😉
  • Lambdas are super fun. Expressive, powerful and of course productive.
  • Easy to use and useful ranges.
  • Easy to add custom get and set methods to public fields. Pair that with simple functions. You have got properties without much boilerplate code.
  • The default arguments and named arguments are pretty cool
  • You can use == for checking equality, no need for equals calls.
  • The is operator provides automatic smart casts. When you write if (param is String) { // code }, the param is cast into a string for you in the block. So no more instance checks.
  • Super expressive maps, filters with lambdas
  • Ability to create custom DSLs
  • Coroutines
  • Awesome tooling support. IntelliJ Idea lets you convert Java code to Kotlin in just a click. You know their IDE is the best, right? But there’s also support for other popular IDEs like Eclipse.

Learning Kotlin

You can also visit us on the Facebook, we have a group named – Kotlin Ninja where some Kotlin enthusiasts learn and share together 🙂