As an Android developer who started working with Android 4 years ago, I had to learn Java in order to create native applications. For the first two years, I learned a lot about Java and I started to feel that I was getting good at it. During this period, I heard you could use Kotlin to create Android apps but I always thought “There’s no way Google would deprecate Java, it’s their main language.”

A year passed, and first-class support for Kotlin was announced at Google I/O 2017. In 2018 Kotlin was voted as the second most loved programming language (StackOverflow).

 

Most Loved, Dreaded, and Wanted Languages

StackOverflow. (2018). Developer survey 2018. [Image]. Retrieved from https://insights.stackoverflow.com/survey/2018

 

Additionally, according to Pusher in “The state of Kotlin 2018”, after the official announcement, the Android community has been migrating from Java to Kotlin rapidly.

 

Kotlin’s growth
Pusher. (2018). The state of Kotlin 2018. [Graphic]. Retrieved from https://pusher.com/state-of-kotlin

 

A few months after Google I/O 2017, I was still using Java because I thought Google would not deprecate it, and you could still use it to make apps, so I thought Kotlin was in its “baby steps”.

Even when I kept thinking I should wait a little bit more, I did not want to lose an opportunity to learn a new programming language, so I decided to experiment a bit. I started reading articles, blog posts, and following tutorials. After a while, I started to get bored because I was only doing tutorials or easy examples of Kotlin. Following tutorials are a good start, but it only shows you the basics of a certain topic, and I really wanted to apply all the new things that I had been learning to a real project. My prayers were heard and I was assigned to a new project in which I had to start from scratch, so I took the risk to use a new language in a real project and learn on the way.

To my surprise, learning Kotlin was unexpectedly easy thanks to my Java background. If you’re asking yourself, “Should I use Kotlin instead of Java?” Well, yes, you should! But, why?

 

Here are some advantages of Kotlin over Java that to consider:

 

1. Say goodbye to NullPointerException

The NullPointerException is the most common exception for a Java developer that Kotlin wants to eliminate by using Nullable types. A nullable type is an object that can be either null or not, and it is defined by the question mark (?). 

If you try to access some property of a certain String, e.g., the length of b, the Kotlin compiler won’t allow you to compile your code because it detects a prominent NullPointerException (NPE). In order to know the length of a nullable string, you have to tell the compiler that it can access that property only if it is different from null by adding the question mark.

The main benefit of using nullable types is that they give us the chance to avoid an unexpected NPE before our app crashes in runtime.

Nullable types provide this benefit due to Kotlin, which detects a possible NPE and Android Studio won’t let us compile our code until we fix it, ensuring that our application is null-safe. However, you may keep in mind that Kotlin does not solve the NPE issue, but it forces you to prevent this exception when your app is running.

 

2. Extension functions

An extension function is a way in which you can add new functionality to an existing class without having it inherit from the class. For example, if you want to remove the last character of a String:


3. Reduce boilerplate 

Boilerplate is the repetitive code that you see in almost every place of your project. A really cool example to identify a repetitive code is a POJO class in Java.

You can create the same POJO class in Kotlin by defining a data class. 


4. Data class

The example above is using a data class; we can use a data class when the main purpose of the class only holds data. Likewise, it gives us the chance to avoid adding unnecessary code to every class we need.

 

5. Interoperability

Kotlin can work with Java in the same project without any trouble because both languages have similar bytecode structure. If you are migrating your app or you want to add a feature (built with Kotlin) in your existing Java application you can do it.

 

6. Android Studio IDE

Android studio has grown a lot, and its compatibility with Kotlin is excellent. Also, it has a feature which lets you convert Java code into Kotlin code by just doing a simple copy/paste, or with a few clicks. This is a useful advantage if you are considering migrating your Java app, but keep in mind that you have to be careful because you are going to use Android Studio to migrate your full code. I prefer to use this feature only to convert little pieces of code.

 

It’s not all a bed of roses.

Kotlin is not a perfect language. In fact, it has cons that you may be interested in knowing before choosing it as your main language to develop Android applications.


Learning curve if you are not a Java developer

I mentioned that if you are a Java developer, the learning curve is effortless but, it may be difficult if you are learning on your own without having an expert Kotlin developer helping you or without any Java experience.

Speed compilation
When we talk about speed in compilation time, Kotlin seems to be slower than Java in some cases when trying to perform clean builds.

Find a Kotlin expert
There are a lot of Kotlin developers available in the market, but if you want to find an experienced mentor that helps you improve your skills, it may be a difficult task.

A few learning resources
As I mentioned before, the Kotlin community has been growing fast, but even so, finding a good learning resource could be difficult if we compare it with Java.

If you are interested in learning Kotlin but you don’t know how to start or where to start, you can visit these links to learn more about it:

  • The official Kotlin page is the official documentation that Kotlin gives us. It is easy to read and it has a lot of good examples.
  • Android code labs are a bunch of awesome tutorials made by Google developers.
  • Android Weekly is a free newsletter that helps you to stay cutting-edge with your Android Development skills. Every week you will receive an email with several topics, tutorials, and posts about Android development.

 

Conclusion

Everything about Kotlin has been fascinating. I have encountered zero issues with this language or any implementation that I want to add to my projects. I have been able to solve every challenge I have faced by using Kotlin, without the necessity of adding any Java to my code. 

I do recommend you look for guides when starting to use Kotlin, especially if you’re not a Java developer. Getting help could fast track your learning. Receiving tips, getting feedback, or maybe being told the solution you implemented is not the best; every padawan always needs a Jedi that guides them to the light side of the force. 

If you are still using Java, my suggestion is to try Kotlin. If you have been following Google’s I/O since 2017, you have noticed all examples about new implementations and tools are using Kotlin. If you are a beginner and looking for a language to learn, choose Kotlin and do not worry; there is a lot of good information about how to start. 

 

https://pusher.com/state-of-kotlin#adoption
https://kotlinlang.org/docs/reference/android-overview.html
https://kotlinlang.org/docs/reference/data-classes.html
https://kotlinlang.org/docs/reference/extensions.html
https://insights.stackoverflow.com/survey/2018
https://www.netguru.com/blog/kotlin-java-which-one-you-should-choose-for-your-next-android-app