How to properly use NDK-Build in Android Studio 2.2 Preview 1

Question

Android Studio 2.2 Preview 1 has a new external ndk build feature, but from app/build.gradle snippet shown in official blog post it's not clear at all how to set additional ndk build parameters which Application.mk file usually contains

I'm able to set Android.mk ndk build file via externalNativeBuild, but how could I set the required Application.mk variables?

My Application.mk contains:

NDK_TOOLCHAIN_VERSION := clang
APP_PLATFORM := android-16
APP_ABI := armeabi
APP_STL := c++_static
APP_CPPFLAGS += -std=c++11

Answer 1

Android Studio 2.2 Preview 3 with updated gradle plugin added support for additional arguments. You can set Application.mk and additional configuration like this:

defaultConfig {
  ndkBuild {
    arguments "NDK_APPLICATION_MK:=Application.mk"
    cFlags "-DTEST_C_FLAG1"  "-DTEST_C_FLAG2"
    cppFlags "-DTEST_CPP_FLAG2"  "-DTEST_CPP_FLAG2"
    abiFilters "armeabi-v7a", "armeabi"
  } 
}

If possible I would recommend migrating to CMake build system, because of better C++ code editor and debugging integration in Android Studio. You will find more info on gradle plugin configuration here: https://sites.google.com/a/android.com/tools/tech-docs/external-c-builds.

Edit: From Android Studio 2.2 Preview 5 you must wrap cmake and ndkBuild groups under externalNativeBuild group:

defaultConfig {
  externalNativeBuild {
    ndkBuild {
      targets "target1", "target2"
      arguments "NDK_APPLICATION_MK:=Application.mk"
      cFlags "-DTEST_C_FLAG1", "-DTEST_C_FLAG2"
      cppFlags "-DTEST_CPP_FLAG2", "-DTEST_CPP_FLAG2"
      abiFilters "armeabi-v7a", "armeabi"
    } 
  }
}

Edit 2: It seems that wrapping ndkBuild under externalNativeBuild group does not work because of a bug in build tools.

Answer 2

add-native-code

android {
  ...
  defaultConfig {...}
  buildTypes {...}

  // Encapsulates your external native build configurations.
  externalNativeBuild {

    // Encapsulates your CMake build configurations.
    cmake {

      // Provides a relative path to your CMake build script.
      path "CMakeLists.txt"
    }
  }
}

Note: If you want to link Gradle to an existing ndk-build project, use the ndkBuild {} block instead of cmake {}, and provide a relative path to your Android.mk file. Gradle also includes the Application.mk file if it is located in the same directory as your Android.mk file.