Java can still be used but it's no longer the recommended choice for Android apps. For any new Android apps nowadays you start with Kotlin and Jetpack compose (made by Google).
In fact, I think Google's been saying this for 6-7 years already.
Kotlin compiles to the same JVM bytecode that Java itself does. There is no performance hit. And from a developer's perspective, no it is not a "complication", Kotlin is a much more pleasant and efficient language to program in than Java (in my opinion, and that of many others).