Kotlin vs. Java: What are the popular Key Points for android development


Kotlin vs. Java: What are the popular Key Points for android development

  • In Kotlin No findViewBylds:although a Kotlin class and a Java class perform the same work, the former is much more concise and can reduce the amount of boilerplate you need to write, i.e. findViewByIds.

  • By default null-safe

  • Coroutines – a new feature

  • In Kotlin Data classes – the time saver

  • Extension functions

To use these extensions, you will need to integrate an extra plugin to your module-level build.gradle file (apply plugin: ‘kotlin-android-extensions’). With Kotlin Android Extensions you can import a reference to a View into your Activity file and you will be able to work with that View as if it belongs to the Activity. As a result, you would never need to write another findViewById method again!


After that you can access this TextView by just using its ID:

Here’s the Java equivalent:

You can make out now that Kotlin offers much more concise code than Java, isn’t?


In case, you need a variable to hold a null value then you would need to declare the type as nullable and add a question mark after the type as shown in the example below:

Moreover, the compiler will execute a null-check prior to accessing a nullable variable, thus keeping the code clean by being precise on what can be null and what cannot be; consequently, the bugs are reduced and code, as well as product quality, are improved.

Coroutines – a new feature

While performing a long-running task or CPU-intensive work, in traditional Java development scenario, the calling thread gets blocked until the operation completes.

In Kotlin, a new feature called coroutines was added that allows you to enforce those kinds of operations without blocking a thread. It performs a suspension of coroutine which is a lighter operation.

Coroutines also allow you to create ostensibly synchronous code which in fact is asynchronous yet more clear, concise and readable.

They also have a lower memory usage as they are stackless and do not rely on a virtual machine or operating system.

Data classes – the time saver

As the majority of our applications are data-driven, we generally need to create multiple classes with properties and fields that do nothing but hold data only.

This is usually a very tedious process in Java, as you would need to define a constructor, fields to store the data and at the same time getter and setter function for each field. Additionally, you would need to add hashCode(), equals() and toString() functions.

This is how a simplified version of the class would appear in Java:

public class User {
   private String name;
   private int age;
   public User(String name, int age) {
       this.name = name;
       this.age = age;
   public void setName(String name) {
       this.name = name;
   public String getName() {
       return this.name;
   public void setAge(int age) {
       this.age = age;
   public int getAge() {
       return this.age;

On the other hand, in Kotlin all you need to do is declare the class as well as all its properties in a single line. The beauty of this language is that the compiler will generate all the getters and setters along with the equality members, toString() and a copy() function as shown below:

It infers that what you need to manually write in Java code, the compiler will generate everything in Kotlin.

Extension functions

This is a great feature in Kotlin that allows you to extend a class with new functionality. It is currently missing in Java; however, you might have used it in other programming languages used for Android development like C#.

You can easily call a function from an object through an extension function as though it were a part of its class.

For instance, you can create an extension function by prefixing the name of the class, ‘string’ in this case to the name of the function that you are creating, i.e., ‘styleString’. By the way, how does it work?

You would need to add this function to any file as shown below:

In Kotlin, you can then call this function on instances of the extended class, through the dot notation, as though it were member function of that class:

Kotlin vs. Java: Which one is your choice?

If you too are pondering on which programming language to use for a profitable Android application development – Kotlin or Java, there is welcome news for you. You would be happy to know that you can use both; yes, you heard us right!

In spite of the differences between Kotlin and Java, they are completely interoperable. That means you can call Java code from Kotlin and vice versa. Also, you can have both Kotlin and Java classes aligned side by side within the same project and guess what, it will compile.

Have you tried Kotlin yet? Do you want to continue with Java for your Android development projects? Let’s talk! We would love to hear your views; please leave your comments below.

Leave a Reply

Your email address will not be published. Required fields are marked *