ExternalNativeNdkBuildOptions

Specifies the Application Binary Interfaces (ABI) that Gradle should build outputs for. The ABIs that Gradle packages into your APK are determined by NdkOptions.abiFilter()

In most cases, you need to specify ABIs using only NdkOptions.abiFilter() , because it tells Gradle which ABIs to both build and package into your APK. However, if you want to control what Gradle should build, independently of what you want it to package into your APK, configure this property with the ABI's you want Gradle to build.

To further reduce the size of your APK, consider configuring multiple APKs based on ABI—instead of creating one large APK with all versions of your native libraries, Gradle creates a separate APK for each ABI you want to support and only packages the files each ABI needs.

By default, this property is null.

Specifies arguments for ndk-build.

The properties you can configure are the same as those avaiable in your Android.mk and Application.mk scripts. The following sample specifies the Application.mk for the ndk-build project:

android {
    // Similar to other properties in the defaultConfig block, you can override
    // these properties for each product flavor you configure.
    defaultConfig {
        externalNativeBuild {
            ndkBuild {
                // Passes an optional argument to ndk-build.
                arguments "NDK_MODULE_PATH+=../../third_party/modules"
            }
        }
    }
}

By default, this property is null.

Specifies flags for the C compiler.

The following sample enables format macro constants:

android {
    // Similar to other properties in the defaultConfig block, you can override
    // these properties for each product flavor in your build configuration.
    defaultConfig {
        externalNativeBuild {
            ndkBuild {
                // Sets an optional flag for the C compiler.
                cFlags "-D__STDC_FORMAT_MACROS"
            }
        }
    }
}

By default, this property is null.

Specifies flags for the C++ compiler.

The following sample enables RTTI (RunTime Type Information) support and C++ exceptions:

android {
    // Similar to other properties in the defaultConfig block, you can override
    // these properties for each product flavor in your build configuration.
    defaultConfig {
        externalNativeBuild {
            ndkBuild {
                // Sets optional flags for the C++ compiler.
                cppFlags "-fexceptions", "-frtti"
            }
        }
    }
}

By default, this property is null.

Specifies the library and executable targets from your ndk-build project that Gradle should build.

For example, if your ndk-build project defines multiple libraries and executables, you can tell Gradle to build only a subset of those outputs as follows:

android {
    // Similar to other properties in the defaultConfig block, you can override
    // these properties for each product flavor in your build configuration.
    defaultConfig {
        externalNativeBuild {
            ndkBuild {
                // The following tells Gradle to build only the "libexample-one.so" and
                // "my-executible-two" targets from the linked ndk-build project. If you don't
                // configure this property, Gradle builds all executables and shared object
                // libraries that you define in your ndk-build project. However, by default,
                // Gradle packages only the shared libraries in your APK.
                targets "libexample-one.so",
                        // You need to configure this executable and its sources in your
                        // Android.mk file like you would any other library, except you must
                        // specify "include $(BUILD_EXECUTABLE)". Building executables from
                        // your native sources is optional, and building native libraries to
                        // package into your APK satisfies most project requirements.
                        "my-executible-demo"
            }
        }
    }
}

If you don't configure this property, Gradle builds all executables and shared object libraries that you define in your ndk-build project. However, by default, Gradle packages only the shared libraries in your APK.