Android makefiles are an essential piece of the NDK building process. Thus, it is important to understand the way they work, to build and manage a project properly.
Compilation settings are defined though a set of predefined NDK variables. We have already seen the three most important ones: LOCAL_PATH, LOCAL_MODULE, and LOCAL_SRC_FILES. But many others exist. We can differentiate four types of variables, each with a different prefix: LOCAL_, APP_, NDK_, and PRIVATE_.
APP_variables refer to application-wide options and are set inApplication.mkLOCAL_variables are dedicated to individual module compilation and are defined inAndroid.mkfilesNDK_are internal variables that usually refer to environment variables (for example,NDK_ROOT,NDK_APP_CFLAGSorNDK_APP_CPPFLAGS)PRIVATE_prefixed variables are for NDK internal use only
Here is an almost exhaustive list: