In the last decade, the Java Virtual Machine (JVM) has evolved from being the home of Java alone into a vibrant multilingual platform. While Java remains the cornerstone of enterprise software development, the landscape around it has diversified. Kotlin, Scala, and Groovy, along with a new wave of functional and experimental languages, now compete and collaborate within the same ecosystem.
To explore how this ecosystem is evolving, what makes each language unique, and where the platform might be headed next, we sat down with Pavlo Sloboda, Senior Software Developer at ELEKS.
What’s the current place of Java, Kotlin, Scala, and Groovy in today’s JVM ecosystem?
Java remains the heart of the JVM ecosystem – stable, corporate, and technically conservative. Kotlin, now the official Android language, is also widely used on the server side; it’s modern, concise, and fully interoperable with Java. Scala continues to push toward functional expressiveness and complex type systems, while Groovy keeps its stronghold in DevOps and scripting.
All four languages depend directly on the JVM but have evolved to serve different niches: Java stands for stability, Kotlin for productivity, Scala for powerful type systems, and Groovy for scripting flexibility.
Importantly, the coexistence of these languages within a single project or even a single service is now a practical reality. For example, microservices or libraries can include both Kotlin and Java side by side, while Scala or Clojure components integrate seamlessly through the shared JVM bytecode.
What are some standout features other JVM languages have that Java still lacks?
Even though Java 25 has caught up in many areas with features like records, sealed classes, pattern matching, and virtual threads, other JVM languages still offer extra convenience and expressiveness:
- Kotlin: null safety at the compiler level, extension functions, data classes, coroutines, smart casts, default and named arguments, and strong DSL support.
- Scala: advanced pattern matching, algebraic data types (ADTs), higher-kinded types, full type inference, functional collections, for-comprehensions, and deep integration with Akka.
- Groovy: dynamic typing, metaprogramming, string interpolation, closures, lightweight syntax, and powerful DSL creation capabilities.
In short:
- Kotlin is the “modern Java”, practical and elegant.
- Scala is for expressive, type-rich, functional programming.
- Groovy shines in scripting and DSLs.
How do innovations in the JVM itself affect these languages? And why can’t language evolution stay fast forever?
The JVM evolves independently, but projects like Valhalla, Loom, and Panama eventually benefit all languages that compile to bytecode. Kotlin and Scala often integrate new JVM features quickly, sometimes even before Java itself.
However, no language can evolve rapidly forever. The more code, libraries, and enterprise systems depend on it, the harder it becomes to adapt them to new paradigms. Each innovation requires compatibility checks, documentation updates, and legacy maintenance.
That’s the tradeoff: even modern JVM languages like Kotlin or Scala can’t instantly adopt every new idea, as long-term stability and ecosystem compatibility matter more than raw innovation speed.
Can any JVM language replace Java long-term? Which has the best future potential?
A complete replacement of Java is highly unlikely — its ecosystem is just too massive and stable. Kotlin is the closest contender, especially in Android and backend development, but it coexists with Java rather than replacing it. Scala and Groovy remain more niche, with Groovy gradually declining in use.
There are also interesting contenders:
- Clojure: functional, data-first, and great for concurrency.
- Frege: a Haskell-like, purely functional JVM language.
- Gosu: an enterprise-friendly DSL-orientated language.
- GraalVM / Truffle: a multi-language platform that can run JavaScript, Python, R, Ruby, and custom DSLs on the JVM with high performance.
What’s your overall outlook for the JVM ecosystem?
- The future of the JVM is polyglot.
- Java remains the foundation.
- Kotlin leads in productivity.
- Scala and Clojure drive expressiveness and functional programming.
- GraalVM is the strategic platform enabling cross-language execution.
This multi-language reality is already happening in production systems — the JVM has become flexible enough for almost any kind of workload. Still, each language’s evolution is naturally constrained by the need to maintain backward compatibility and ecosystem stability.
Related insights
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