Java vs. Kotlin: The Key Differences Explained

Mobile apps have become indispensable for most businesses. With these apps, customers can more easily purchase your products, interact with your company, get help, and even spread the word about your products and/or services. And given that currently 60.67% of all web traffic is coming from mobile devices, you can no longer deny the staying power of phones-as-computers. That number will only continue to rise, which means every business is going to have to add a mobile app to stay competitive in an already overly competitive world. For that, it’s purely a Java vs. Kotlin proposition.

As far as mobile operating systems, if you look at the global numbers, Android is the clear winner, with a 72.26% market share. That means if your company plans on doing global business, Android had better be a part of your strategy.

For that, you’ll need either Java or Kotlin. But which should you choose? Both languages are perfectly capable for the Android platform, but only one has Google’s seal of approval as the “official language” for apps.

Let’s take a look at both of these languages so you can see the key differences.

What Is Java?

Java has been around for nearly 30 years. The language was first created by James Gosling in May 1995 for Sun Microsystems and has become one of the most used languages on the planet. With a current TIOBE index of 3, Java is showing no signs of going away.

Java was created to be a small, reliable, portable, distributed, real-time operating platform, but has evolved into something much greater than was originally planned. There are two reasons for that. The first is web applications. The second (and most important) is that Java became Google’s go-to programming language for the Android operating system. And although the majority of Android applications aren’t written in Java, the OS itself is.

But Java isn’t limited to mobile apps. You’ll find Java used for games, cloud computing, big data, AI, and even IoT. Java has developed such a large following because A) it can do so much and B) there are a great many available resources for the languages. Java has a tremendously active community, a ton of development tools, and is completely platform-independent.

Java was originally created to be a “write once, run anywhere” language, which allowed developers to use a single language to create applications that could run within a JVM runtime environment that could be deployed to any platform. Java also depended heavily on sandboxing, which meant rich client applications could be deployed more easily and securely in an enterprise environment.

Java has become so widely used, you shouldn’t have any problem locating a Java development service to help create the perfect portable app for your needs.

Advantages Java

Java has a number of advantages that help make it such a popular language among programmers and businesses, including the following:

• It’s easy to learn – Java was originally designed to be easy to learn and use.
• It’s object-oriented – Java is an object-oriented language, so it’s easy to create modular programs and code that can be reused.
• It’s platform-independent – This means it will run on any operating system.
• It’s very stable – Java, and the applications written with it, are very stable.
• It’s secure – Java avoids certain security issues by using explicit pointers to reduce threats.
• It provides automatic garbage collection – Java ensures that when an object is no longer used by a program, it will be automatically collected and removed.
• It’s multi-threading – Java can run more than one thread at a time to maximize CPU utilization.
• It’s distributed – Java is a distributed language, which means it provides a mechanism for sharing data and programs with multiple computers to increase application performance.
• It enjoys a massive community – With Java, there’s never any shortage of help to be found.

Disadvantages of Java

• It’s not a fast language – Java consumes a good deal of memory and is considerably slower than similar languages.
• Its GUIs are outdated – Java GUIs look like they were built in the late ’90s or early 2000s, so it’s not very modern looking.
• It doesn’t offer data backup – Java provides no facility for data backup.
• It’s not easy to read – Java code is not nearly as succinct as similar languages.

What Companies Use Java?

There are tens of thousands of major companies using Java today, including the following:

• Uber
• Airbnb
• Google
• Pinterest
• Netflix
• Instagram
• Spotify
• Amazon

What Tools Integrate With Java?

Because Java has been around for so long, there are a large number of tools that seamlessly integrate or work with the language, including the following:

• Jenkins – for CI/CD
• Site24x7 – for Java application monitoring
• ManageEngine – proactively monitors Java applications and infrastructure performance
• JUnit – a Java testing tool
• NetBeans – one of the most popular IDEs on the market
• Apache Maven – software project management tool
• Mockito – a Java mocking framework that helps developers write clean code

What Is Kotlin?

Although Google uses Java as the primary programming language for the Android operating system, on May 7, 2019, Google dubbed Kotlin the official language for Android applications. That doesn’t mean those two languages are completely separate. In fact, there are still Android applications written in Java, but the majority of apps for Google’s mobile platform are written in Kotlin.

Kotlin was originally created by Dmitry Jemerov (the lead developer at JetBrains) in July 2011, after he realized that most languages didn’t offer the features he required. The Scala language was considered, but Jemerov found it to be far too slow at compiling. Because of this, he set out to create a language that offered the features of Scala with a much faster compile time. Thus, Kotlin was created.

A year after its creation (in February 2012), JetBrains released Kotlin under the Apache 2 open-source license. The name was inspired by the island of Kotlin (a nod to Java being named after the island of the same name).

With a TIOBE index of 26, Kotlin is not nearly as popular as Java. Even so, thanks to the popularity of Android, you won’t have any problem finding a Kotlin development company anywhere in the world.

Advantages of Kotlin

Kotlin has plenty of advantages, most of which point to it being quite easy to learn and employ. Those advantages include the following:

• It’s concise – Kotlin makes it possible to write less code. The benefit of writing fewer lines of code means your developers will introduce fewer bugs.
• Written by developers for developers – Kotlin was created by those in the industry, so by design, it solves many challenges developers face.
• Easy to learn – Kotlin is easier to learn than many other general-purpose languages. And because Kotlin is fully compatible with Java, you can make it work with existing code.
• Zero runtime overhead – The Kotlin standard library is lean and fast because it serves as an extension of the Java standard library.
• Multi-platform development – Kotlin can be used for Android app development and even integrates with JavaScript, so you can migrate your front-end apps to Kotlin with little effort.
• No null reference – Kotlin’s type system practically eliminates the “billion-dollar mistake” that is null references.

Disadvantages of Kotlin

Kotlin does have its disadvantages, such as:

• It has fewer tools – Because it’s a less mature language than Java, Kotlin doesn’t enjoy nearly the number of tools and integrations.
• It’s slower to compile – Although Kotlin compiles faster than Scala, it’s still slower than Java.
• Smaller community – Where Java has a massive community, Kotlin is far behind in that area, meaning it might be harder to find support.

What Companies Use Kotlin?

Because Kotlin is used for Android app development, you can be certain there are a large number of companies that make use of the language, including the following:

• Udemy
• Slack
• Robinhood
• CRED
• Delivery Hero
• Tech Stack
• Tinder
• HENNGE K.K.
• Pinterest
• Postmates
• Uber
• Evernote
• Coursera

What Tools Integrate With Kotlin?

You won’t find nearly the number of tools that integrate with Kotlin as with Java. However, there are some important tools to consider, such as the following:

• Android Studio
• IntelliJ Idea
• Eclipse IDE
• Android KTX
• Jetpack Compose

Key Differences Between Java & Kotlin

There are a few important differences between Java and Kotlin, including the following:

• Primary usage: While Java is used as the primary programming language for the Android operating system, Kotlin was dubbed the official language of Android applications.
• Object-oriented: Kotlin combines features from both object-oriented and functional programming, whereas Java is limited to only the object-oriented methodology.
• Extensions: Kotlin allows users to create and use extension functions, whereas Java does not.
• Conversions: Java supports implicit conversions, whereas Kotlin does not.

What Does the Future Look Like?

There is no doubt that both Java and Kotlin have bright futures ahead. Given that Java is the official programming language for the Android operating system and Kotlin has been declared the official language for Android apps, you can be certain neither is going anywhere. On top of that, Java has a bright future with web apps and A.I., so its future is all but guaranteed.

The only thing that might change this is if Google finally migrates from Android to Fuschia, which doesn’t seem to be happening any time soon.

Java vs Kotlin: Who Wins?

If you’re looking for a language that can be used to create apps for any platform, Java is the clear winner. If, however, you’re looking to create apps for the Android operating system, Kotlin is the way to go.

When to Use Java

Java should be considered when you want to create numerous types of applications that will run on any platform that includes the Java Virtual Machine. With Java, you can create games, mobile apps, web apps, AI apps, apps that work with big data, and apps that run on IoT devices.

When to Use Kotlin

Kotlin is your best choice for writing concise Android apps with less code and fewer bugs.

If you enjoyed this, be sure to check out one of our other Java articles:

• Java Concurrency: Master the Art of Multithreading
• Java Garbage Collection
• Java Integration Testing Explained With Examples
• 10 Best Java NLP Libraries & Tools
• The 10 Most Popular Java Frameworks