Java vs Kotlin for Android: Which Language Should You Choose?

21CTO editorial: When you hear Android development, which language comes to mind? This article compares Java and Kotlin to help developers decide.

Most developers think of Java because many Android apps are written in it. Two years ago, Google introduced Kotlin at I/O, raising the question of its market potential.

Kotlin Overview

Kotlin, developed by JetBrains and officially supported by Google, is an open‑source language that runs on the JVM. Companies such as Pivotal, Atlassian, Pinterest, Evernote and Uber use Kotlin for Android development. According to AppBrain, Kotlin‑based apps hold 25.30% market share and account for 40.76% of new app installations.

Why Kotlin is a leading language for Android?

Higher efficiency: Concise syntax and streamlined deployment boost team productivity.

100% Java interoperability: Kotlin can call Java methods, easing migration for projects with large Java codebases.

Ease of maintenance: Broad IDE support, including Android Studio, lets developers use familiar tools.

Reliability: New Kotlin versions remain compatible with older ones, simplifying version management.

Easy to learn: Simpler than Java, even for those without prior mobile development experience.

Android Studio support: Native extensions and tools enable simultaneous use of Java and Kotlin.

Kotlin drawbacks

Compilation speed: Benchmarks show inconsistent compile times, sometimes fast, sometimes slow.

Smaller community: The Kotlin ecosystem is still growing, offering fewer resources than Java.

Java Overview

Java remains one of the top languages for application development, offering object‑oriented features and supporting everything from Android to enterprise web applications. The latest TIOBE index still ranks Java as number one.

Java strengths

Portability: The JVM allows Java programs to run on any system, and most Android apps are written in Java.

Strong developer community: Large GitHub and Stack Overflow communities provide extensive support.

Cross‑platform: Java is not limited to Android; it can be used for many platforms.

Java drawbacks

Performance: Higher memory consumption and slower execution compared with some modern languages.

Verbosity: Java requires more boilerplate code, leading to longer development cycles and more potential errors.

Feature Comparison

Static members (Java) vs. string templates (Kotlin)

Top‑level types (Java) vs. singletons (Kotlin)

Non‑private fields (Java) vs. null‑safety (Kotlin)

Wildcard types (Java) vs. extension functions (Kotlin)

Checked exceptions (Java) vs. smart casts (Kotlin)

Conclusion: Java remains the dominant language for Android, but Kotlin’s modern features make it a compelling choice for future development. Developers should stay updated with both.

Happy coding!