What is Kotlin?

No matter your skill level as a developer, you have no doubt heard about the programming language Kotlin. It is known as Java's replacement and as a powerful tool for mobile app development. In this article, we will look more deeply at Kotlin, what it is, how it works, and why it has the potential to become the next Java and, at the very least, a major player in the developer world.

Kotlin is an open-source programming language that is statically typed, which essentially means that you have to explicitly declare variable types, and those variables data types get checked at compile-time versus run-time. It was developed by the good folks at JetBrains, who are well-known for their host of developer tools, which include integrated development environments (IDEs), code editors, debuggers, and even educational tools you can use to better learn how to program. The Kotlin project started back in 2010 and got its first official release in early 2016. The current release is version 1.5.10 and was published at the end of May 2021.

In addition to being statically typed, Kotlin is also a combination of both object-oriented programming (OOP) and functional programming, combining elements of both worlds.

Kotlin Versus Java

Keeping in mind that Kotlin was thought to be a replacement for the Java programming language, it should come as no surprise that Kotlin has much in common with its unofficial "Uncle." Because of this, Kotlin is 100% interoperable with Java. This means that you can call Java code from within Kotlin and vice versa. Kotlin also shares all of the major libraries with Java and works on the same major IDEs as Java.

With all of the similarities between the two languages and the fact that you can mingle the code so easily, it is important to note that there are differences between Java and Kotlin.

Code Precision

Java and Kotlin are largely capable of the same tasks. However, achieving those tasks and creating apps or software can differ greatly. This is in part due to the fact that Kotlin is much more precise than Java. This means that your Kotlin code can achieve the same results as Java but requires fewer lines of code. This means your programs will be more efficient, more easily maintained, and have more readability.

This is also known as concision and essentially ensures that other programmers will be able to review your code and understand it at a higher level, and thus, be able to add on or make changes in a more straightforward manner. It also reduces errors in code and increases productivity.

Null Safety and Checked Exceptions for Mobile App Development

A common issue with mobile app development is the NullPointerException, which occurs when Java programmers assign a null value to object references. This leads to crashes in Android apps, and, in fact, it is one of the main reasons Android applications crash.

Kotlin helps developers avoid this issue, as it has built-in null safety, which prevents variables and objects from being assigned null values.

Not quite the same, but another area where Kotlin outpaces Java is the arena of exception handling. Unlike Java, where developers need to handle or throw exceptions, Kotlin does not have checked exceptions. This, and the aforementioned null safety, mean that developers can write less code in their applications, as they do not have to handle null safety problems or checked exceptions.

Data Classes

When you create a data class in Java, developers have to define constructors, fields for data storage, getter and setter functions, and more. Kotlin eliminates this extra work by adding the data keyword, which you can include in your class definition. If you do, the compiler then adds your getters and setters for you, saving you extra code and effort.

What Can Kotlin Be Used For?

As you probably guessed by now, Kotlin can be used for pretty much anything Java can be used for. You can perform server-side and client-side development, create apps for Android and iOS phones, web development, desktop software creation, and more. As the language gets updated, you'll even be able to tackle programming for the IoT, thanks to its incoming support for embedded development.

At the moment, the language is really prized for its mobile app development features. In fact, Google recently hailed Kotlin as its language of choice for app development, which is a pretty powerful endorsement, to say the least. A nod like that means that the language isn't going anywhere any time soon and will only continue to grow in popularity.

Hello World Kotlin vs Java Example

Every developer knows the importance of creating their first program. Traditionally, we all learn the fabled "Hello, World!" application. It's a right of passage, akin to a guitar player learning "Smoke on the Water" by Deep Purple. If you somehow managed to avoid this ultra common learning experience, the purpose of "Hello, World!" is simple - you write a small program designed to print the text "Hello, world!" to a computer screen. Metaphorically, it's your way to introduce yourself to the world.

In Kotlin, you would create the "Hello, World!" app in the following way:

fun main() {
            	printIn("Hello, World!")

To achieve the same result using Java, you would take a slightly different approach. For starters, the Kotlin compiler creates the class for us in the above code example. In Java, we must create a class ourselves. Consider the following code demonstrating how to create the "Hello, World!" program in Java:

class HelloWorld {
            	public static void main(String[] args) {
                            	System.out.printIn("Hello, World!");

Another way our "Hello, World!" app differs in Kotlin versus Java is the fact that in Kotlin, there is no need to use semi-colons. You can see this when you look at the program in Java, where we end our System.out.printIn line with a semi-colon.

Companies That Use Kotlin

As stated, Kotlin is rapidly growing in popularity. In addition to Google tipping its hat to Kotlin, many other organizations have begun to use Kotlin for their app development. JetBrains, the creator of Kotlin, is one obvious company. Others include such notable names as Netflix, Trello, Uber, Pinterest, Capital One, and Foursquare - to name but a few. You can see how flexible Kotlin is as a language by looking at the diversity of the companies on that list, everything from streaming media companies to project management, social media, and financial services.