I’ve got an Android project going that uses FFmpeg to build short video files (more on this at a later date). Normally, you run FFmpeg in a terminal window or command prompt. It updates you on the status of a task in that terminal window. I’ve instrumented FFmpeg on Android with some C code and a JNI interface. When I execute FFmpeg from an Android app those status updates are written to logcat.

I learn a Kotlin thing everyday. Today’s thing, “Enforcing-Inheritance-Generic-Thing-in-Kotlin” (I’m terrible with names and terms, there’s an official term for this that I cannot remember). I have a function that starts an activity for a result. I want to limit this function to only be able to start activities extending an abstract class, FooActivity. In Java: private void start(Activity activity, Class<? extends FooActivity> cls) { // some stuff with intents } In Kotlin: