Kotlin – Definition, Use Cases and Best Practices at a Glance
Modern language from JetBrains; Google’s preferred language for Android. Interoperable with Java, more concise and safer.
What is Kotlin? Google's Preferred Android Language
Kotlin has replaced Java as the preferred language for Android. Since Google recommended Kotlin in 2019, adoption has grown fast. Kotlin offers a more modern, concise syntax, null-safe types and full interoperability with existing Java. It also powers backend (Ktor), multiplatform (KMP) and UI (Compose).
This glossary entry for Kotlin gives you a clear Definition, practical Use Cases and Best Practices at a glance – with examples, pros and cons, and FAQs.
What is Kotlin?
- Kotlin – Modern language from JetBrains; Google’s preferred language for Android. Interoperable with Java, more concise and safer.
Kotlin is a statically typed language developed by JetBrains, first released in 2016. It compiles to JVM bytecode (runs wherever Java runs), to JavaScript (Kotlin/JS) and to native (Kotlin/Native). It is fully interoperable with Java: Kotlin can use Java libraries and vice versa. Kotlin Multiplatform (KMP) shares business logic between Android, iOS, Web and Desktop.
Jetpack Compose – the modern declarative UI toolkit for Android – is written in Kotlin.
How does Kotlin work?
Kotlin is compiled to JVM bytecode by the Kotlin compiler; on Android it is compiled with the Android Gradle Plugin to DEX. Features like null safety (types are non-nullable by default), extension functions, data classes, coroutines (lightweight concurrency) and sealed classes make code shorter and safer than equivalent Java. Kotlin Multiplatform uses expect/actual for platform-specific code.
Practical Examples
Android app with Jetpack Compose: Declarative UI in Kotlin – less code, better performance and testing than the old View system.
Backend with Ktor: Kotlin web framework for REST APIs with coroutines and native Kotlin syntax.
Kotlin Multiplatform: Shared network and business logic for Android and iOS – only UI is platform-specific.
Spring Boot + Kotlin: Enterprise backend combining Spring’s robustness with Kotlin’s clarity.
Typical Use Cases
Android: New apps and migrating Java apps to Kotlin
Backend: Servers with Ktor, Spring Boot or Micronaut in Kotlin
Multiplatform: Shared code for Android and iOS with KMP
Data science: Kotlin notebooks (Jupyter) for analysis and viz
Scripting: Build scripts (Gradle Kotlin DSL) and automation
Advantages and Disadvantages
Advantages
- Null safety: NullPointerExceptions caught at compile time
- Concise: Often 30–40% less code than Java (data classes, extensions)
- Java interop: Existing Java codebases can adopt Kotlin gradually
- Coroutines: Clean async code without callback hell
- Google backing: Preferred for Android with strong IDE support
Disadvantages
- Compile time: Kotlin compiles a bit slower than Java (improving)
- Smaller community: Fewer answers and libraries than Java
- Learning: Advanced features (coroutines, sealed classes, DSLs) take time
- KMP on iOS: Kotlin Multiplatform for iOS is less mature than Flutter/React Native
Frequently Asked Questions about Kotlin
Should I learn Kotlin or Java for Android?
Kotlin. Google recommends it for Android. New Android APIs and Jetpack libraries are Kotlin-first. Jetpack Compose is Kotlin-only. Java is still useful for legacy codebases, but for new projects there’s no reason to choose Java over Kotlin.
Can I migrate existing Java code to Kotlin?
Yes, gradually. Kotlin and Java can coexist. IntelliJ has a Java-to-Kotlin converter (starting point only; manual cleanup needed). Prefer writing new code in Kotlin and migrating Java when you touch it. Full rewrites are rarely necessary.
Kotlin or Flutter for Android?
Native Kotlin + Compose when: you need max performance, full Android APIs, Android only, and Kotlin expertise. Flutter when: you want one codebase for iOS and Android and cost matters. KMP is a middle path: shared logic in Kotlin, native UIs per platform.
Direct next steps
If you want to apply or evaluate Kotlin in a real project, start with these transactional pages:
Kotlin in the Context of Modern IT Projects
This page provides a concise definition of Kotlin, practical use cases and best practices at a glance — everything you need to evaluate the technology for your next project. Kotlin falls within the domain of Technology and plays a significant role across a wide range of IT projects. When evaluating whether Kotlin is the right fit, organizations should look beyond the technical merits and consider factors such as existing team expertise, current infrastructure, long-term maintainability, and total cost of ownership.
Drawing on our experience from over 250 software projects, we have found that correctly positioning a technology or methodology within the broader project context often matters more than its isolated strengths.
At Groenewold IT Solutions, we have worked with Kotlin across multiple client engagements and understand both its advantages and the typical challenges that arise during adoption. If you are unsure whether Kotlin suits your particular requirements, we are happy to provide an honest, no-obligation assessment. We analyze your specific situation and recommend the approach that delivers the most value — even if that means suggesting an alternative solution.
For more terms in the area of Technology and related topics, see our IT Glossary. For concrete applications, costs, and processes we recommend our service pages and topic pages — there you will find many of the concepts explained here put into practice.
Related Terms
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