Kotlin vs. Java Full Comparison

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Kotlin vs. Java Full Comparison

Key Points

  • Kotlin and Java code are interchangeable. That means you can call scripts written in either language into scripts written with either language
  • Kotlin uses both object-oriented programming and functional-oriented programming. This allows for the creation of functions separate from objects and classes.
  • Kotlin allows for the creation of extension functions. Extension functions allow the coder to add new functions without declaring them. These functions act like static functions and can become part of created classes or predefined classes.
  • Kotlin doesn’t use semicolons as part of the code syntax. Java-writers may have grown accustomed to the semicolon structure, but with Jet Brain’s language it’s out the window.
  • Kotlin is an improved programming language over Java. With the support for interchangeability and its enhanced structure, it is poised to become the go-to programming language for web and mobile developers.

Aside from the ever-improving and changing hardware landscape in technology, there is also a movement to improve the way those devices are coded. As of 2019, Google has made Kotlin the official program language for Android.

If you’ve used an Android application made after the change, you’ve likely been running Kotlin developed applications without even noticing. That’s because this switch is for developers.

Most people are familiar with the term “Java,” even if only by name. It was released in 1995 as the backend programming language for web applications, games, audio, and video. It became so popular that it sprouted sub-languages and prompted operating system developers to include a virtual machine specifically for reading and running applications.

Kotlin was designed to provide a better experience for developers and end-users by preventing common problems without changing compatibility. Java was the first full feature programming language to take over running the internet. Being among the first of anything in software development leads to unintentional problems down the road. Kotlin was designed around common flaws in the Java structure to remove some of those unintentional problems. Part of the reason no one noticed the change as an Android user is that Kotlin compiles to the same base code that can be read by the Java Virtual Machines (JVMs) installed in modern devices. This allows developers to switch from Java to Kotlin easily.

Kotlin vs. Java: Side-by-Side Comparison

In today’s development landscape, Java is no longer the center of attention. With backing from Google, Jet Brain’s Kotlin has taken over as the go-to choice in programming languages for Android and other JVM compatible systems such as iOS and popular web browsers.

That doesn’t mean Java is obsolete. Instead, both languages exist side-by-side. Some developers are too experienced and dependent on Java to retire it. At the same time, they have begun to recruit Kotlin coders to expand their horizons. As it has function-oriented features, it can be a perfect language to accompany Java applications. This is especially true with its ability to compile to the same bytecode Java uses.

What it is:Programming languageProgramming language
Primary Use:Coding language used for creating programs and applicationsCoding language used for creating programs and applications
Initial Release:20161995
Technical Committee:Jet BrainsSun Microsystems, Oracle
Influential Developers:Jet BrainsSun Microsystems
Open format:YesYes
Technologies Influenced:Android SDK, Android, iOSJavaScript, Web Browsers, Animation

What is Kotlin?

Kotlin is an improved programming language over Java.

Kotlin is a multi-platform general-purpose programming language with type inference that is statically typed. The language was designed to compile code into bytecode that can be read by any JVM. This has to lead to it often being referred to as a “JVM Language”.

At first glance, a comparison between codes written in either language shows a lot of similarities and differences. The code structure is very similar between them with more similarities than differences. As both languages are interchangeable, the amount of similarities is not surprising.

Here are the key features to note with Kotlin:

  • Trimmed coding
  • JVM support which allows support for both object-oriented programming and functional-oriented programming.
  • Compiles quickly.
  • Support for extension functions without changing code.
  • Can be written in IDE or command-line interface
  • Smart feature casting

What is Java?

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Almost every operating system uses Java.


Java is a multi-platform object-oriented programming language. It was released in 1995 and became the code of the internet. Applications are written with the language run in web browsers, games, social media applications, and media players.

Upon its initial release, Sun Microsystems sold the code language to developers with the motto “write once, run anywhe0072e”. A promise that was fulfilled by implementing JVMs into the user’s operating system. Even browsers now have a standalone JVM installed to remain independent from system features.

Here’s a quick list of the key features of Java:

  • “Write once, run anywhere”, massive platform support
  • Designed for building object-oriented programs
  • Multithreaded with automatic memory management
  • Allows for network-centric functions like distributed computing

What Are the Differences Between Kotlin vs. Java?

Besides the features available in Jet Brain’s newer language like functional-oriented programming, Here’s a list of the differences between the two programming languages:

  • Kotlin allows the creation of extension functions which Java does not.
  • Kotlin does not support implicit conversions, while Java does.
  • Kotlin does not have null variables or objects. Java makes heavy use of null variables and null objects.
  • Java supports static members while Kotlin does not.
  • Java requires a variable datatype specification while Kotlin does not.
  • Kotlin does not use semicolons.
  • Kotlin supports language scripting.

Kotlin vs. Java Full Comparison FAQs (Frequently Asked Questions) 

Is Kotlin better than Java?

Jet Brain’s language incorporates the elements of Java into itself. It then adds extra features available through functional-oriented programming and structural changes. These changes allow the scriptwriter more flexibility with their code.

The same features that increase flexibility like type inference and the removal of the semicolon syntax structure can also make it easier to start learning Kotlin than Java. It also helps that it will not enforce object-oriented programming requirements like containing everything within a class. This helps to cut down on the overall length of each code script.

Is Kotlin replacing Java?

Kotlin isn’t replacing Java, but it is offering something a little bit better for new programmers to work with. Java isn’t going anywhere anytime soon. Developers are already well-versed in it and have careers using the language to create functions for applications. What’s more likely to occur is a slow fade. It will continue to be in use as Kotlin grows. Eventually, Kotlin will replace it at its position of dominance, but Java-writers will still be valuable.

Is Kotlin harder than Java?

If you’re switching from Java to Kotlin, it can be a little difficult to learn the syntax differences and free your mind from the constraints of strictly object-oriented programming. If you’re new to programming, it is no more difficult to learn as a starting programming language than Java. It is also compatible with JVM-capable software which is in practically everything.

There is also a large community online that offers support for new coders learning the language. With online tutorials and community support, you can learn either language at a decent pace. If you are having difficulty choosing between the two languages, I would recommend giving Kotlin a try. It has the support of big tech companies like Google and can compile code into the same bytecode that is read by JVMs.

Which language is easier to learn, Kotlin or Java?

I would argue that Kotlin is easier to learn. This is partly due to the removal of the semicolon. Type inference is also a major factor. New coders can often forget to define types, classes, and objects. However, the Java community is older and much larger. There are thousands upon thousands of tutorials available online for free. You can easily switch between resources and examples that are readily available through nearly every code site.

Kotlin’s community isn’t small, but it hasn’t had the time to grow to the same influential size the Java community has. It will get there eventually. That’s not to say that there aren’t resources to learn Kotlin online. There’s a big enough base of tutorials and coding community for you to learn it just as fast.

Which language was developed first, Kotlin or Java?

Java was developed long before the idea of Jet Brain’s language blipped into existence. Development for Java started in 1991 and it was officially released in 1995. Jet Brain began development twenty years later in 2011 and was released in 2016.


Are Kotlin and Java interchangeable?

These programming languages are interchangeable. That means you can call Kotlin code in Java and you can call Java code in Kotlin. That means learning Kotlin is not only beneficial as a forward-thinking subject, but you can also continue the previous work done by Java developers before you as well as coworkers using Java. It also allows Java programmers to expand their capabilities by adding Kotlin to their projects.

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