android - Read build arguments from NDK code

Question

I have an NDK file that inject my api key into my app, the code works correctly:

#include <jni.h>

JNIEXPORT jstring JNICALL
Java_yt_javi_nftweets_ui_main_MainActivity_getTwitterKey(JNIEnv *env, jobject instance) {

    return (*env)->  NewStringUTF(env, "my_twitter_key");
}

I would like to change my_twitter_key by an custom build argument

externalNativeBuild {
  ndkBuild {
    arguments "-DTWITTER_API_KEY=my_twitter_key"
  }
}

And read that argument inside the method Java_yt_javi_nftweets_ui_main_MainActivity_getTwitterKey

Answer 1

You could add a define to your cFlags and stringify it in your C code:

android {
    defaultConfig {
        externalNativeBuild {
            ndkBuild {
                cFlags "-DTWITTER_API_KEY=my_twitter_key"
            }
        }
    }
}

---

#define xstr(s) str(s)
#define str(s) #s

...

return (*env)->NewStringUTF(env, xstr(TWITTER_API_KEY));