Kotlin vs. Java Comparison

Is it necessary for the developers to learn Kotlin? Are businesses making a quick shift to Kotlin? Will Kotlin replace Java’s emperor throne? There are mixed opinions for all of the above questions! However, there has to be a tie-breaker between the two android app development programming languages. In this blog, we have run down comparison and tried to simplify which overrules the other and in which segment. Read this blog and find out more about the debate, Kotlin Vs. Java.

Android app developers are in a constant dilemma about which language to describe as their expertise, Java, or Kotlin? Needless to say, Java was the only player in the market, until 2017 when Google announced Kotlin as the official language for Android app development.

The news spread like wildfire, leaving everyone startled with the question, how the dynamics will change now? Kotlin is relatively new, but it is considered to have a more mature ecosystem.

In this blog, we will discuss the new hurly-burly topic Kotlin Vs. Java in depth. The table of contents is,

What is Kotlin?

Pros and Cons of Kotlin

What is Java?

Pros and Cons of Java

Comparison chart between the two

We hope that this blog helps you in deciding which language will work best in your project favor?

Kotlin vs. Java for Android App Development

What is Kotlin?

Kotlin is a general-purpose, statically typed programming language based on the Java Virtual Machine. It is a modern language having all qualities of Java, which makes it easy to build scalable mobile applications and overcome many challenging tasks. JetBrains introduced Kotlin in 2011 with an intention to add some more features to Java development. But it soon gained tremendous momentum and became an alternative to Java.

Kotlin makes app coding experience practically sound and more effective. You can compile it to Javascript and interoperate it with Java. Kotlin is supported by prominent IDEs and is compatible across Java versions 6 or 8. All you have to do is install the Kotlin Plugin and allow it to configure the project.

You can use Kotlin for Android, Native, JVM, and browser app developments.

Pros of Kotlin:

Concise code:

A major difference between Java and Kotlin is code writing. In Java, you may write 50 lines of code to execute a program, but you can compile the same in 1 or 2 lines using Kotlin. Thus, Kotlin reduces the boilerplate code, which increases productivity and leaves no room for error and bugs.

An upgraded user-experience:

Since Kotlin is safe and almost bug-free, there are less chances of app crashes, and thus the user experience is uninterrupted.

The Fail-Fast module:

You can immediately report issues in coding and save the app from a downfall. Google’s introduction of the Fail-Fast module identifies the problem and stops Android developers from moving ahead in the project. This was never possible while using Java language.

Faster development:

Kotlin helps in building clean APIs using which a lot many tasks can be accomplished in a project. Additionally, the brevity factors make it capable of solving a series of problems, which thus mitigates the chances of any bugs in the app. This reduces the app development time considerably, resulting in a quick app turnaround.

Few other benefits on the list are:

You can make a quick shift between Java to Kotlin because of the availability of Java bytecode.

Kotlin extends built-in null safety support which was missing with Java language;

You can use the advanced Anko Library available on GitHub for project development.

Top brands using Kotlin programming language are:







Cons of Kotlin:

Difficult to learn:

While most of the developers have their-go-to language as Java, it is difficult for them to learn Kotlin. This programming language has a steep learning curve, and this less excites developers.

Slow compilation speed:

No doubt, Kotlin surpasses every weakness of Java, it falls short in the compilation speed. It shows a slower compilation speed than Java.

Young and small community:

Kotlin was introduced by Google almost four years ago, and thus its community is yet growing. The Kotlin community is young, and it has fewer learning resources. This makes it difficult for developers to find answers to their questions instantly. Without a second thought, the community will expand, but until then, you have to deal with this limitation.

Difficulty in finding developers:

Since the language is new, it can be difficult for you to find an experienced developer for your project. Well, we would say, everyone out there is still learning the language.


Android Studio’s feature of auto-compilation and compilation run comparatively slow in Kotlin as compared to Java.

Kotlin is a highly declarative language that can possibly generate a significant amount of boilerplate.

Kotlin vs. Java for Android App Development

What is Java?

As mentioned-, Java is the go-to programming language of most of the developers around the world. It is an object-oriented programming language that was developed by Sun Microsystems. Java has been in the market for around two decades, making it the oldest and the easiest language to learn.

Java is again an open-source language providing ample tools and libraries to the developers. It is the bed-rock of Android app development, making it a lot many tasks easier and less complicated during development. It is platform-independent and can be used to build cross-platform as well as native applications.

Pros of Java:

Being in the industry for around 20 years, most of the developers have achieved expertise in Java coding. And also, they can teach the programming language to the newbies. Java has a comparatively easier learning curve than Kotlin.

It has a wide-open-source ecosystem, using which a developer can swiftly build an android app.

Java is lighter in weight and more compact, thereby giving a faster user experience. It can be easily optimized to ensure consistent and improved app performance.

On running a Kotlin Vs. Java comparison, then, Java is more flexible to run on both, virtual machine and browser window.

As developers today have hands-on experience in building Java-based Android applications, you can build an application without any hassle.

It has an accelerated assembly within Gradle.

Java follows the logic, “Write once, run anywhere.”

It has a larger community of developers who constantly work behind the language upgrades. If you have any queries or wish to fix a problem, you can post in the community, and you will have a prompt solution to it.

Cons of Java:

As mentioned above, with Java, you have to write many lines of code, which increases the chances of making errors and bugs.

Java has some inherent limitations leading to problems in API design.

Java is slower as compared to Kotlin and other languages.

It consumes a lot of memory.

Top brands using Java as the programming language:








Next is the comparison chart between the two big players, Java Vs. Kotlin

Null SafeJava allows allocating null to any variables which lead to many problems for the developersKotlin doesn’t allow assigning any value to the variables. If the user tries to assign a null value, the code will fall during the compilation
Extension FunctionA Java functionality can not be extended to another class. You need to create a new class and inherit it from the parent classKotlin allows extension of functionality with an existing class
Checked ExceptionsJava extends its support for checked exceptions which makes it possible to code robustly. The developers can declare and catch the exception smoothlyKotlin doesn’t support checked exceptions. This is good and also bad, in a way.
Development speedJava development speed is comparatively fasterKotlin facilitates speedy development
Coroutines supportBy using Java, you can create multiple threads in the background, but it has no coroutines support which makes it difficult to manage complex tasksKotlin also allows you to create multiple threads in the background, but it also has coroutine support. Hence, complex tasks can easily be executed without any blockage
Lambda expressionJava doesn’t support Lambda expressionsKotlin supports Lambda expression which is important for treating anonymous functions as values
Community supportJava is old and has a vast community to supportKotlin is relatively new and has limited community members and resources
Data classesIn Java, you need to define a constructor, variables, Getter and setter methods, functions and more to have a class that can hold only data and nothing elseKotlin has a different ball game here. You just have to declare a class with keyword “data” and the rest of the thing will be taken care of by the compiler
Smart CastsWhile using Java, you need to check the variable type and cast accordinglyOn the contrary, Kotlin supports smart casts that will handle the casting checks. It will check the immutable values and cast accordingly
Type interfaceYou have to clearly specify each variable straightforwardKotlin doesn’t need you to specify each variable explicitly. However, if you wish to specify a variable straightforward, you can do it
Functional programmingUntil Java 8 was released, Java did not have functional programming. But today, it supports a subset of Java 8 features for android app buildingKotlin blends procedural and functional programming languages.
Invariant arrayJava doesn’t support an invariant arrayKotlin supports an invariant array
Singleton objectsAllows you to create singleton objectsIt easily creates a singleton objects

Which companies switched to Kotlin from Java?

Kotlin overrules Java when it comes to performance, simplicity, maintainability, lightweight, and robustness. The year between 2017 and 2018 was a gamechanger for Android app developers.

There was exponential growth in the demand of Kotlin and, in many respects, wins the debate. A number of hot-shot brands thought of migrating to Kotlin from Java, few of them are listed below.

1. Pinterest

2. Postmates;

3. Corda;

4. Evernote;

5. Coursera;

6. Uber;

7. Basecamp3;

8. Shadowsocks;

9. Kickstarter;

10. Square;

11. Gradle

Kotlin’s popularity is rising, and for all good reasons, it will replace Java (that doesn’t mean it is dead). The adoption rate of Kotlin was observed to be 7.54% back in September’17. A 2018 survey conducted amongst almost 100,000 Stack Overflow users reveals that around 60% of them use Kotlin. Udemy adds on to this news saying, Kotlin was their hottest development skill in the year 2018.

Today, Kotlin overtakes Scala and Clojure, making itself the second most popular language on the JVM.

Will Kotlin replace Java?

The simplest answer to this is, No! Both languages have powerful features to savor the developers. Both languages have their strengths as well as weaknesses; however, Kotlin is a modern answer to older Java android app development. You can simultaneously operate Java and Kotlin both in an existing project.

Kotlin enhances all the Java features, and it looks like all modern applications will be based on it. Even Android Studio extends excellent support to Kotlin. It is indeed difficult to evaluate which one is best or reap more benefits to your project; however, Kotlin aims to bring out the best from your project.

We have an experienced team of android app developers who will be delighted to help you with their expertise.

blog Author - kodytechnolab

Sagar Bagsariya

Principal Mobile App Developer