In Android app development and backend solutions, the comparison between Kotlin and Java is one of the most common topics among developers, companies, and tech teams. Since Google announced Kotlin as an official language for Android in 2017, its adoption has been growing steadily. Even so, Java is still a strong, mature, and widely used language. This article explores the advantages that Kotlin offers compared to Java, what unique features it has, its possible disadvantages, and the programming paradigm it follows. If you need to make an informed decision about which language is better for your next development projects, keep reading until the end.
Why do developers prefer Kotlin over Java?
The preference for Kotlin is not just a passing trend. This language has proven to be a modern, safer, and much more concise option for mobile and backend development. Its cleaner syntax allows developers to write less code to achieve the same results as in Java. This not only speeds up the work but also reduces the chance of making mistakes.
One of Kotlin’s main strengths is how it handles nullability. In Java, ‘NullPointerException’ errors are one of the most common causes of runtime failures. Kotlin, on the other hand, includes null safety by default, which improves code security.
Another important reason for its popularity is full interoperability with Java. This means you can use Java libraries in Kotlin projects without problems, which is very useful when you can’t migrate all the code at once. Also, since 2019, Google has officially declared Kotlin as the preferred language for Android, which has led many large companies to adopt it as their mobile development standard.
What can Kotlin do that Java can’t?
Although Kotlin and Java share many features, Kotlin includes modern tools that are not available in Java or require external libraries or more complex code structures to use. A clear example is extension functions, which let you add functions to existing classes without having to inherit or change the original code. This gives developers more flexibility without losing readability.
Kotlin also stands out because of its coroutines, which make asynchronous programming easier and more efficient. Unlike Java threads, coroutines help manage concurrent tasks with less memory and better performance. Another helpful feature is Kotlin’s smart casts, which avoid the need for explicit casting after checking the type of a variable—making the code cleaner and simpler.
In addition, Kotlin supports functional programming in a smoother way, with more powerful lambda expressions and a more declarative coding style. These features make Kotlin an expressive, readable, and easy-to-maintain language—qualities that are especially important for agile teams and projects that need high productivity.
What are Kotlin’s disadvantages compared to Java?
Despite its many benefits, Kotlin also brings some challenges compared to Java, especially in contexts where teams need to adopt it quickly or have little experience with the language. One of the main issues is the learning curve. Even though it’s easier to learn for developers who already know Java, Kotlin introduces new ways of thinking and writing code, so it takes time to adapt.
Also, in some environments and large projects, Kotlin’s compile times can be a bit slower than Java’s, although this has improved in recent versions. Another point to consider is that Kotlin’s community is still smaller than Java’s. This means there might be less documentation, fewer examples, and not as many specific online solutions.
Finally, some legacy tools and older platforms are not fully optimized for Kotlin. So, if a project depends on technologies that only support Java completely, this can be a limitation.
Is Kotlin functional or object-oriented?
A common question among beginners is whether Kotlin is a functional language or an object-oriented one. The answer is that Kotlin is a hybrid language. On one hand, it supports full object-oriented programming (OOP), with classes, objects, inheritance, and other OOP principles—just like Java.
On the other hand, Kotlin also includes many functional programming features. These include lambda functions, higher-order functions, immutability, and a more declarative style that allows developers to write more expressive and less error-prone code. This flexibility is one of Kotlin’s biggest advantages. It allows developers to choose the approach that fits each project best: object-oriented, functional, or a mix of both.
To clonclude, we can ask ourselves what’s the difference between Kotlin and Java. One way to answer is to ask: can Kotlin do everything Java can? The short answer is yes. Kotlin can do everything Java does—and even more. Thanks to full interoperability, you can use any Java code inside a Kotlin project without problems. And with its modern approach, concise syntax, and advanced features, Kotlin is a safer, more productive, and more attractive option for modern software development.
However, choosing between Kotlin and Java is not about which one is better in general, but which one fits your project best. It’s important to consider your team’s experience, your current infrastructure, compatibility with existing tools, and business goals. Both languages are still evolving and coexisting, but Kotlin is clearly becoming the future of Android development and a strong, modern alternative to Java.