Java

Java served as the foundation of Android development from the platform’s inception in 2008 until Kotlin’s emergence as Google’s preferred language in 2019. As a mature, object-oriented language with vast libraries and tooling, Java enabled Android to become the world’s most popular mobile operating system. While Android uses a specialized implementation that compiles to Dalvik bytecode rather than standard Java bytecode, the language syntax and core concepts remain familiar to millions of Java developers worldwide.

Despite Kotlin’s official preference status, Java remains fully supported for Android development and continues to power countless production apps. Many enterprise codebases, established libraries, and Android documentation examples still use Java. The language’s extensive ecosystem, long-term stability, and widespread developer expertise make it a pragmatic choice for teams with existing Java investments or working on large-scale legacy applications that require ongoing maintenance.

For new Android projects, Kotlin offers significant advantages in safety, conciseness, and modern features, making it the recommended choice. However, Java’s continued viability means developers should understand both languages. The two coexist seamlessly in Android projects, allowing teams to leverage existing Java code while writing new features in Kotlin. Understanding Java remains valuable for reading legacy code and maintaining the massive body of Java-based Android resources.