Java is a great programming language. It is modern, object-oriented, and offers excellent community support. But, does that make it the best programming language for doing almost everything around us!

Well, of course, NO!

That’s where Kotlin comes in!

Kotlin is also a modern programming language released in 2011 by JetBrains after active development for more than a year. Initially, it didn’t gain traction due to performance issues and a lack of features. But, slowly, it attracted developers across the board. However, it started getting tons of attention when Google acknowledged Kotlin in 2017 and started providing first-class support for Android.

Things started changing, and here you are looking for answers!

  1. What is Kotlin?
  2. What is Java?
  3. How does Kotlin compare to Java?
  4. Advantages and Disadvantages of Kotlin and Java

Kotlin vs Java

If you are in a hurry, then check out the table for quick reference.

Feature Kotlin Java
Code Compilation Slow compared to java Faster than Kotlin
Checked Exceptions No Yes
Extension Functions No Yes
Constructors Support Kotlin supports secondary constructions(one or more) Java doesn’t let you create secondary constructors
Development Speed Faster compared to Java Slower due to boilerplate code
Coroutines Not available Available
Primitive Types The primitive type variables are treated as objects The primitive type variables are not treated as objects
Delegation Native Support No Yes
Inline Functions Yes No

Before we go deep into their difference and learn which one you should prefer at what stage, let’s first learn more deeply about each one of them.

What is Kotlin?

Kotlin is a general-purpose programming language that is statically typed and comes with type interfaces. It is completely interoperable with Java and has its own version of JVM, which utilizes the Kotlin standard library.

The main reason behind Kotlin’s release is productivity. Java is an excellent programming language but does slow down the rate at which you can build your app. Another reason Kotlin is useful is that it can also be compiled to JavaScript, which means that you can use React in your projects without any compatibility issues.

In short, Kotlin is:

  • General-purpose programming language
  • Offers compilation to javascript
  • Enables developers to be productive
  • Offers Java interoperability

History of Kotlin

To better understand Kotlin, let’s take a look at some of its important history moments:

  • Kotlin v1.0 was first launched in 2016.
  • Google stepped up for Kotlin as they announced Kotlin support for Android
  • Kotlin v1.3 supported asynchronous programming in 2018.
  • In 2019, Google announced that Kotlin is their preferred programming language for Android.

What is Java?

Java is one of the most popular programming languages. It is an object-oriented, class-based programming language that follows the principle of “write once, run everywhere”. Sun Microsystems developed it.

Java’s inception was fairly good. Also, the popularity of Android made it necessary for developers to learn about it.

But, what made Java tick? Well, according to us, the following features made Java such a developer-friendly programming language.

  • It is a class-based, object-oriented language.
  • It supported the idea of “write once; run anywhere.” This gave developers the freedom to experiment with the programming language and run on machines with JVM installed.
  • Lastly, it supported concurrency – a way to execute multiple statements at once.

History of Java

  • Java was initially known as OAK. Its main aim was to handle portable devices.
  • OAK failed, but Sun managed to revive the project by renaming it to Java in 1995 and using it to build the web.
  • Java improved over the years adding more functions and features.
  • In 2009, Oracle Corporations acquire Sun which meant that Java now falls under Oracle Corporations.

How does Kotlin compare to Java?

Compilation Time

Overall, the compilation time of Java is better compared to Kotlin. So, any code compiled in Java code for the first will be 15-20% faster than Kotlin.

Development Speed

When it comes to development speed, Kotlin easily beats Java. This is partly because of how data classes function in each of the programming languages. In Java, the developer needs to write tons of boilerplate when defining the class. Also, some of the several classes might not provide any real functionality.

In Java, the developer first needs to write constructors, followed by the definition data-storage field, and then get their functions up and running.

In Kotlin, that’s not the case as it provides a very simple way to define classes as it requires only the data keyword for the class definition. The magic is done by the Kotlin compiler as it generates the rest of the code itself.

Coroutines Support

Both Java and Kotlin offer their own way to handle multiple operations. In the case of Java, a background thread is run to provide a way to run multiple threads. This works, but it adds unnecessary complexity to the design.

Kotlin solves it by providing a nifty feature known as co-routines. With coroutines, a developer can create additional threads which provide better task management using less demand for the

Null Safe

Kotlin solves the Null safe problem of Java. By default, Java does not make all variables null safe and that’s why you have the NullPointerExceptions. This leads to multiple issues and mistakes if not handled properly. To solve the problem, Kotlin makes all types of non-nullable providing the necessary protection against this mistake. So, if you assign a null value to a variable and try to run it — the compilation will fail.

Extension Functions

In Kotlin, developers can easily add new functionality to a class using extension functions. This concept is now new and is already used in other object-oriented programming languages such as C#. The process of creating one and using it is easy in Koltin.

Java does not provide any similar functionality and hence functions cannot be extended.

Community Support

There is no doubt that Java is widely supported and accepted by developers all across the world. Java’s age also helps it to have wider community support. So, you are likely to find solutions for your Java problems.

On the other hand, Kotlin has decent community support.

Advantages and Disadvantages of Kotlin and Java

Both Java and Kotlin has their own advantage and disadvantages. By going through their advantages and disadvantages, you will get a better understanding of what each one of them has to offer.



  • Java documentation is detailed.
  • Offers reusable code option.
  • Great marketplace with tons of developers.
  • Offers a good collection of 3rd party libraries.
  • Allows multi-threaded environment
  • Great performance out of the box
  • Gives developers access to checked exceptions for error solving and detection.


  • Requires more manual work to maintain the code
  • It is not ideal for Android API design due to limitations
  • JIT compiler makes programs slow
  • JIT compiler also have higher machine requirement to run successfully
  • The garbage collector can make the developer lose control over memory management


Now that we have gone through Java’s advantages and disadvantages. Let’s go through the advantages and disadvantages of Kotlin.



  • Kotlin comes with null safety support aimed for better Android development.
  • Kotlin is a user-friendly programming language.
  • Kotlin multiplatform framework enables one-time common codebase extraction.
  • Supports extension functions
  • Takes less time to write code compared to Java
  • Easier to deploy
  • Less error-prone as it is more concise.


  • Kotlin is fairly new and hence offers a small community of developers
  • Slower compilation speed
  • Being a highly declarative language means excess creation of boilerplate code in JVM


Both Java and Kotlin are here to stay as they provide value in their own way. So, which programming language are you going to use for your next project? Comment below and let us know.

You also need to know that Kotlin has a steep learning curve compared to Java. This means that startups may find it hard to adapt to Kotlin for their new projects.

Let’s summarize the key differences below so that you can get a good understanding and summary.

  • Kotlin offers an extension function. In comparison, Java doesn’t support extension functions.
  • Koltin supports both functional and object-oriented programming. Java, on the other hand, is mostly about object-oriented programming.
  • Java supports implicit conversions whereas Kotlin doesn’t.
  • Java doesn’t support Lambda expressions whereas Kotlin does.
  • Java supports the concept of null variables or objects, whereas Kotlin doesn’t do that.
  • Kotlin supports language scripting capabilities via Gradle build scripts. Java doesn’t.
  • Java requires developers to use semicolons, whereas Kotlin doesn’t require one.
  • Kotlin’s primitive types are objects, whereas Java primitive types do not object.
  • Java utilizes static members. Kotlin has no such feature.

Both programming languages have their own purpose. If you are looking for a general-purpose programming language, then Java is always a better pick. But, if you are someone who needs a programming language for rapid Android development, then Kotlin is a better pick!