Macro android_application 

macro_rules! android_application {
    ($build:expr) => { ... };
}

Makes a shared library the native side of an Android application.

$build is a function that returns the application builder (fn() -> AppBuilder), usually AppBuilder::configure::<App>().use_android(): what an application overrides CreateAppBuilder and CustomizeAppBuilder for in the reference. The macro writes the one symbol the library exports, JNI_OnLoad, which the virtual machine calls when the application class of the Java layer loads the library.