Java and Kotlin have been at the forefront for Android development and beyond. Java, a very reliable language with over two decades of dominance, has shaped the foundation of countless software applications and systems. Kotlin, on the other hand, is a newer language designed to improve upon Java, offering modern syntax, enhanced safety, and greater developer productivity.
But how do these languages compare in terms of features, performance, use cases, and community support? Was Kotlin created to replace Java? And is it worth learning Kotlin in the year 2024? This post will answer all these interesting questions.
Java, introduced in 1995 by Sun Microsystems and powered by the JVM (Java Virtual Machine), is a general-purpose, class-based, object-oriented programming language designed to minimize implementation dependencies. Java is used extensively in web applications, back-end systems, Android development, and enterprise solutions.
Kotlin, released as a project by JetBrains in 2011, is a statically typed, open-source programming language that also runs on the JVM. Fully interoperable with Java, it’s an official language for Android development and has quickly gained popularity due to its modern features and simplicity. In 2017, Google announced Kotlin as an officially supported language for Android development, cementing its place in the developer toolkit.
The language features show the specific characteristics of both languages and their functionalities.
One of Kotlin’s biggest advantages is its clean and concise syntax. While Java will most likely require verbose code to accomplish a very simple task, Kotlin streamlines common patterns. Consider this example on defining a User class in both Java and Kotlin:
In just one line, Kotlin creates a fully functional class with a constructor, getter for the name property, and built-in toString(), equals(), and hashCode() methods implemented based on the properties of the class.
This brevity not only reduces boilerplate (sections of code that are repeated in multiple places with little to no variation), but also makes the code easier to read and maintain.
NullPointerException (NPE), famously referred to as the “billion-dollar mistake,” has plagued developers for decades. Java does not have a built-in null safety, leaving room for runtime errors. Now, developers have to depend on manual checks or additional libraries to avoid null pointer exceptions.
Kotlin tackles this with its robust null safety system. By distinguishing between nullable (String?) and non-nullable (String) types, Kotlin forces developers to handle null values explicitly at compile time. Let’s take a look at this simple Kotlin code as an example:
This code shows Kotlin’s null safety feature, which uses nullable types (String?) and the Elvis operator (?:) to safely handle null values without risking a NullPointerException, unlike Java, which requires manual checks by the developer.
This feature of Kotlin significantly reduces runtime errors, and ultimately leads to safer and more reliable applications.
In Java, every variable has to be explicitly typed, and this will eventually lead to a verbose code. Kotlin’s type inference allows developers to omit explicit type declarations when the type can be deduced from the context. Let’s demonstrate this using the code below:
Notice, the type String is required to be written explicitly because Java does not automatically figure out what type the variable should be based on the value.
In Kotlin, you don’t have to explicitly write the type of the variable if it can be figured out. Kotlin automatically understands that message is of type String because “Hello, World!” is a string. You don’t have to write String explicitly.
Kotlin’s conciseness extends beyond syntax to features like extension functions, which allow developers to add new functionality to existing classes without modifying them.
In the Kotlin code example below, the extension function isPalindrome() is added to the String class, enabling you to call isPalindrome() on any string object as if it were a built-in method.
Notice that the function isPalindrome() is added to the String class, allowing any String object (like word, in this case) to use this function.
Java doesn’t have extension functions. To achieve the same functionality in Java, you would need to modify or create a utility class to add this functionality.
In Java, you can’t directly add isPalindrome() to the String class itself. Instead, you’d have to use a utility method inside a separate class, like StringUtils.
Such features in Kotlin encourage modular, reusable code, a significant advantage over Java.
Here we’ll take a close look at how these two languages compare in terms of their compilation speed and runtime performance.
Java is 15-20% faster in terms of compilation speed, as its compiler is optimized from decades of usage. Kotlin’s additional checks, like the null safety, can slow down compilation, though the difference is quite negligible for most projects, and their incremental builds are comparable.
Since both Java and Kotlin run on the JVM, their runtime performance is nearly identical. Benchmarks show that for most use cases, any performance difference between the two languages is insignificant. Developers need not worry and can be rest assured that Kotlin does not in any way compromise runtime efficiency.
Here we’ll take a look at the development tools and build tools available to support both languages.
Both Java and Kotlin are well supported by modern IDEs like IntelliJ IDEA and Android Studio. However, Kotlin has an edge in Android Studio, as it’s the preferred language for Android development. Features like instant previews, refactoring tools, and integrated testing are optimized for Kotlin.
Kotlin can be easily integrated with build tools like Gradle. Its Kotlin-based DSL (domain-specific language) makes build scripts cleaner and easier to understand when compared to XML-heavy configurations in Java.
Here we’ll look at the community support and library availability of the two languages.
Java’s community is one of the largest and most active in the programming world, alongside JavaScript and Python. With over 25 years of usage, Java boasts an extensive collection of tutorials, frameworks, and open-source libraries.
Kotlin’s community, on the other hand, is smaller but rapidly growing, thanks to its adoption in Android development and beyond. KotlinConf (the official Kotlin conference by JetBrains) and active forums ensure developers have access to resources and support.
Java’s library ecosystem is unmatched, with robust frameworks like Spring and Hibernate dominating back-end development. However, Kotlin-specific libraries like Kotlin Coroutines (for asynchronous programming) and Ktor (for building web applications) are gaining traction and expanding Kotlin’s reach.
Now let’s take a closer look at the use cases of the two languages with regards to Android development and back-end development.
Google’s 2017 announcement of Kotlin as a first-class language for Android development was a game-changer. Features like null safety, coroutines, and extension functions make Kotlin the preferred choice for Android developers. Although Java is still widely used, new projects and updates to Android tools prioritizes Kotlin.
Java’s dominance in back-end development is undisputed, with frameworks like Spring Boot and Apache Kafka powering enterprise-grade applications. Kotlin is carving out a niche in the space as well. It’s an attractive choice for back-end development due to its modern syntax and compatibility with Java. Additionally, may developers these days will prefer to use Kotlin for back-end development as a result of the official support from Google.
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Kotlin is unlikely to replace Java entirely. While Kotlin has become the go-to language for Android development, Java remains a cornerstone for back-end systems, enterprise applications, and legacy codebases. Instead of being a replacement, Kotlin will complement Java, allowing developers to leverage both languages where they excel.
Yes, learning Kotlin in 2024 is highly worthwhile. This is because of Google’s continuous support and the growing adoption of the language, so therefore, proficiency in Kotlin is a valuable skill for any Android developer. Additionally, Kotlin features like null safety and coroutines are becoming standard expectations in modern programming.
Yes, Google officially prefers Kotlin for Android development. Since 2017, Kotlin has been prioritized in Android documentation, tooling, and updates. While Java is still supported, Kotlin is clearly the favorite for modern Android applications.
Kotlin’s modern enhancements and concise syntax make it ideal for Android development, while Java’s stability and extensive ecosystem remain indispensable for enterprise and back-end solutions.
Choosing the right language depends on your project goals, but leveraging tools like Stackify Retrace ensures seamless performance monitoring and debugging for both. Together, they empower developers to build efficient, robust applications. Start your free trial today!
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