gistfile1.txt

public void subscribeToMqtt(Message message) {
    executor.cppMethod();
}    

public class TestExecutor {      
    static {         
        System.loadLibrary("native");     
    }     
    public native String cppMethod(); 
} 

cpp: 

JNIEXPORT jstring JNICALL methodNAME (JNIEnv* env, jobject thisObject) {
    printf("START PI TEST! \n");     
    return env->NewStringUTF("Hello from C++ !!"); 
}