C++ for the UI is extremely uncommon, and very second-class citizen. C++ for parts of an app, though, is common enough. For example Facebook's Litho is a Java

C++ for the UI is extremely uncommon, and very second-class citizen. C++ for parts of an app, though, is common enough. For example Facebook's Litho is a Java API, and uses a large chunk of the Android SDK's systems. But it also uses a layout engine in C++. This hybrid approach isn't uncommon, and Android Studio has some nice features to work in this mode like being able to follow usages across the JNI boundary and to auto-generate the JNI stubs.