Have you ever heard about Kotlin programming language? If so, you probably heard about it in the context of Android development. However, Kotlin is capable of so much more and brings game-changing features. Let me give you a brief introduction to Kotlin. Kotlin is an open-sourced statically typed programming language developed by JetBrains. It was officially released in February 2016. JetBrains developed Kotlin for two reasons. The first one was to try and drive the sales of IntelliJ IDE and the second one was to create their own programming language to overcome the limitations they faced every day. Since JetBrains products heavily relied on Java, they wanted Kotlin to work seamlessly with it and that is why it was designed to work with Java Virtual Machine (JVM). Kotlin supports both object-oriented programming and functional programming. They can even be used at the same time. In this article, I will introduce you to the advantages of Kotlin over Java.

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1. Null Safety

One of the most critical and dangerous errors that any programmer can face is the null pointer exception (NPE). It is even known as the billion-dollar mistake, but what if I told you that Kotlin has a built-in feature to eliminate the risk of NPEs as much as possible? First of all, Kotlin provided two types of variables nullable and non-nullable variables, where nullable variables are allowed to hold null and non-nullable variables are not allowed. With that in mind, Kotlin can identify the variables that can be null at compilation time. So, if a reference of a variable that may be null is called, Kotlin returns an error. In order to overcome this error, you must adopt one of the following solutions:

1. The first solution is simple using an if condition to handle the case of the variable being null. However, this solution is only applicable for immutable variables, variables that have constant values that will not change over time, to ensure that the variable value will not be changed to null after the condition.
2. The second solution is to use safe calls. Safe calls is an operator that returns null in case the variable you are trying to access is null otherwise it returns the reference that you intended to access.
3. The last solution is to use the Elvis operator, which is simply the same as the if condition but written in a more concise way.

NPE can still occur in Kotlin in only two ways either by explicitly throwing a null pointer exception or by using the not-null assertion operator. This operator throws an exception at runtime in case the variable you are referencing is null.

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2. Extension Functions

Have you ever felt that a class is missing a very important function and wished it was there? To overcome this problem in Java, you probably would have to write a static function that takes an instance of the class to apply the logic on. If you want to use this function across your entire project, you will have to place this function in a generic class and import it into the desired classes. However, in Kotlin things are much easier. Kotlin lets you extend a class with functions without altering the original source code and use it just like any class method. It does not stop her you can even extend a class with as many properties as you want. This can also be applied to third-party libraries.

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3. Coroutines

Both Kotlin and Java support concurrency. However, Kotlin brings some advantages with coroutines over Java threads. First, Kotlin coroutines let you write asynchronous non-blocking code, but that’s ok Java also provides the same thing. However, Kotlin coroutines allow us to write code that looks and feels like synchronous code, which makes it simpler and easier to use. They are also lightweight, making them much more efficient to run many coroutines without overwhelming the system compared to Java. In Java, if a thread is blocked, it continues consuming the system resources, but Kotlin coroutines don't have this problem thanks to its suspension mechanism. Kotlin Coroutines also supports a built-in cancellation mechanism that helps release resources that are no longer needed for canceled coroutines, which Java does not support. Finally, Kotlin coroutines perform better in terms of switching between threads over Java.

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4. Multiplatform Support

As I mentioned earlier, probably you heard about Kotlin in the context of Android development. However, Kotlin brings much more. So, let me introduce you to Kotlin multiplatform. Kotlin allows you to write a single source code that can be used across different platforms including Android, IOS, web, desktop, and server-side while trying their best to maintain the flexibility and benefits of native programming. It does not stop here; they also allow the use of platform-specific API to ensure the best possible performance. Kotlin multiplatform supports the use of each platform-specific Java library such as Spring boot.

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5. Overriding Properties

Just like Java, Kotlin also provides inheritance in the exact same way. Also, methods overriding is available in Kotlin just like Java. However, Kotlin introduced a feature that is not available in Java, which is property overriding. In Kotlin, you can override the value of a parent class property in the child class. You can also override the declaration of a property from val (immutable) to var (mutable), but not vice versa.

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6. Interoperability with Java

While building Kotlin, Java interoperability was in mind. As we mentioned in the beginning, most of JetBrains’ products are built using Java. Therefore, Kotlin had to be interoperable with Java. You can call Java code in Kotlin without any problems and vice versa. In fact, you can convert between any of them to the other as both are compiled to JVM bytecode at the end.

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Conclusion

In my opinion, Kotlin is an immensely powerful programming language, and I believe that in the near future, it will be the go-to programming language in different scoped projects. However, I would like to say that both Java and Kotlin are great programming languages. Each brings their advantages and disadvantages. Deciding which one of them is the best relies on the context of the project in hand and none of them can completely replace the other.