There is no denying the fact that Java is the most popular and widely used programming language when it comes to android app development. The language had been the default code development language for Android until Kotlin came into existence. In its I/O conference of 2017, Google made a breaking news and left the world in awe when it recognized Kotlin as the next coding alternative for Android.

Kotlin’s inception as an official coding language for the Android platform has gotten many business users into the dilemma. There have been quite some years now that developers and programmers have been continuously working with Java to build innovative products for the android market. However, we need to accept that Kotlin is the next big thing. Let’s have a look at 10 reasons why it is so.

  1. You Get A Taste Of Swift

While working with Kotlin you will realize that the platform is technically more advanced and crisp. The Kotlin syntax is clean and modern. An android app development company which would start working with Kotlin will realize that it is possible to guess its aspects due to its intuitively designed syntax. Especially when we are considering it with Java, a well-defined syntax clearly becomes a critical factor. Here’s an example of how a class is declared in Swift and Kotlin:


class Shape {
    var numberOfSides = 0
    func simpleDescription() -> String {
        return "A shape with \(numberOfSides) sides."


class Shape {
    var numberOfSides = 0
    fun simpleDescription() =
        "A shape with $numberOfSides sides."
  1. Kotlin Is An Open Source

Thankfully, Kotlin is an open source programming language. The language was initially created by Jetbrains, the house which also led to IntelliJ IDE. If you are looking forward to converting existing Java code, you can do that with the help of a single-click tool.

  1. Data Classes

Kotlin uses data classes for data containers, representing JSON objects and also for returning compound objects from functions. No denying the fact that Java doesn’t support this special type of classes yet. Eventually, there is a need to implement a custom data class.

A special use case is compound objects returned from functions. Let us take an example that a function that needs to return, say, two objects. If you are working in Kotlin, you can use a data class or a pair:

public class MultiReturn {
    public static void main(String[] args) {
        new MultiReturn().useMulti();
    public void useMulti() {
        Multi multi = helper();
        System.out.println("Multi with " + multi.count + " and " +;
    private Multi helper() {
        return new Multi(2, "test");
    private static class Multi {
        private final int count;
        private final String name;
        public Multi(int count, String name) {
            this.count = count;
   = name;
  1. Null-Safety

Kotlin has done an amazing task of separating the nullable types as well as the non-nullable ones. If you are dedicatedly working with these tools, you may never see a NullpointerException at runtime. The Kotlin programming syntax is focused on removing the perils of null references from code. A typical example would be when in the case of Java, you get a null reference exception when you are accessing a member of a null reference. Kotlin prevents compilation of a  code which assigns or returns a null, making it one of the most important features of Kotlin. Here’s an example:

Initially, Kotlin assumes that value cannot be null:

var a: String = "value"
assertEquals(a.length, 5)

You cannot assign null to the reference a, as it will cause a compiler error.

To create a nullable reference, create append the question mark(?) to the type definition:

var b: String? = "value"
  1. Default Parameters

The way methods which have to be overloaded is where most Android developers find themselves uncomfortable. Here’s an example:

fun argumentValid(num: Int, str: String = "12") {
//All 3 are valid
argumentValid(15, "Hey")
argumentValid(str = "Name", num = 45) //Named argument
argumentValid(45) //usage of default argument

If you are looking for more complex examples, it may lead to redundant code, which can be easily achieved by default parameters in Kotlin. Below is an example of Kotlin default argument.

fun displayBorder(character: Char = '=', length: Int = 15) {
    for (i in 1..length) {
fun main(args: Array<String>) {
    println("Output when no argument is passed:")
    println("\n\n'*' is used as a first argument.")
    println("Output when first argument is passed:")
    println("\n\n'*' is used as a first argument.")
    println("5 is used as a second argument.")
    println("Output when both arguments are passed:")
    displayBorder('*', 5)

  1. Kotlin compiles to JVM bytecode or JS

Java and JS developers are the most interested ones to learn this programming language since it compiles to JVM bytecode or JavaScript. What’s more interesting is that the Android developers who use a garbage collected runtime will also enjoy working with Kotlin programming language.

  1. It’s Java Compatible

While Kotlin is compared with Java on multiple fronts, Kotlin takes a leap ahead with its ability leverage to the JVM and interoperate with Java code. You might be wondering that if Kotlin and Swift were almost alike, then why would Google try to uplift and bring forward a language that was merely used by a small number of Android developers? The simple answer to this is Java compatibility. This is an amazing aspect for Google with Android. Kotlin proves to be a language with interesting opportunities to find its way into the many other areas.

  1. Singleton

One of the favorite features of Kotlin feature is the grace of defining “singleton”. Have a look at the following example to understand how to create a singleton in Java.

public class SingletonInJava {
    private static SingletonInJava INSTANCE;
    public static SingletonInJava getInstance() {
        if (INSTANCE == null) {
            INSTANCE = new SingletonInJava();
        return INSTANCE;

Kotlin defines a singleton in a unique pattern. An Android developer can use a keyword object to define an object which exists only as a single instance.

object SingletonInKotlin {
// And we can call
  1. Local Functions

In most of the cases, android app developers would go ahead and create private methods to be used inside another single method. This is done to increase the readability of the code. However, if you are working with Kotlin, you can make use of the local functions, (inside functions…). Generally, this proves to be a cleaner approach due to the fact that function is only accessible inside the function that uses the local one. Here’s an example:

fun deployVerticles() {
    fun deploy(verticleClassName: String) {
        vertx.deployVerticle(verticleClassName, opt, { deploy ->
  "$verticleClassName has been deployed? ${deploy.succeeded()}")

It defines a local function which is reused twice. This really simplifies the overall code structure.

  1. Default Arguments

Remember the times when you have to duplicate code so that you can define different variants of a constructor? Let’s take an example to understand better:

public class OperatorInfoInJava {
    private final String uuid;
    private final String name;
    private final Boolean hasAccess;
    private final Boolean isAdmin;
    private final String notes;
    public OperatorInfoInJava(String uuid, String name, Boolean hasAccess, 
                              Boolean isAdmin, String notes) {
        this.uuid = uuid; = name;
        this.hasAccess = hasAccess;
        this.isAdmin = isAdmin;
        this.notes = notes;
    public OperatorInfoInJava(String uuid, String name) {
        this(uuid, name, true, false, "");
    public OperatorInfoInJava(String name, Boolean hasAccess) {
        this(UUID.randomUUID().toString(), name, hasAccess, false, "");

However, when you work with Kotlin, you can simply remove these steps by using default arguments.

class OperatorInfoInKotlin(val uuid: String = UUID.randomUUID().toString(),
                           val name: String,
                           val hasAccess: Boolean = true,
                           val isAdmin: Boolean = false,
                           val notes: String = "") {}


What makes Kotlin an amazing language to work with is the fact that it is a clean and straightforward language that is loaded with powerful features. The primary focus of Kotlin is to bring together programming language features together which have proved to be worthwhile for diverse projects. Although Kotlin is versatile enough to be used anywhere, it is primarily used by Android app developers for android development. Most importantly, it is backed up Google’s official support, so android development companies can rely on this language for their projects.

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