Android NDK - Android studio gradle undefined reference to __android_log_write - android-studio

Question

I am trying to debug a JNI C function by inserting log messages, but I can't get it to work. To start with I am just trying to modify the hello-jni example that comes with Android Studio. This is the modified code:
#include <string.h>
#include <jni.h>
#include <android/log.h>
jstring
Java_com_example_hellojni_HelloJni_stringFromJNI( JNIEnv* env,
jobject thiz )
{
#if defined(__arm__)
#if defined(__ARM_ARCH_7A__)
#if defined(__ARM_NEON__)
#if defined(__ARM_PCS_VFP)
#define ABI "armeabi-v7a/NEON (hard-float)"
#else
#define ABI "armeabi-v7a/NEON"
#endif
#else
#if defined(__ARM_PCS_VFP)
#define ABI "armeabi-v7a (hard-float)"
#else
#define ABI "armeabi-v7a"
#endif
#endif
#else
#define ABI "armeabi"
#endif
#elif defined(__i386__)
#define ABI "x86"
#elif defined(__x86_64__)
#define ABI "x86_64"
#elif defined(__mips64) /* mips64el-* toolchain defines __mips__ too */
#define ABI "mips64"
#elif defined(__mips__)
#define ABI "mips"
#elif defined(__aarch64__)
#define ABI "arm64-v8a"
#else
#define ABI "unknown"
#endif
__android_log_write(ANDROID_LOG_ERROR, "TEST_TAG", "Error here");
return (*env)->NewStringUTF(env, "Hello from JNI ! Compiled with ABI " ABI ".");
}
And this is my Android.mk file:
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := hello-jni
LOCAL_SRC_FILES := hello-jni.c
LOCAL_LDFLAGS := -llog
include $(BUILD_SHARED_LIBRARY)
When I use the ndk-build script the libhello-jni.so files get built no problem. When I try to build the project in Android Studio I get the following gradle error message
Information:Gradle tasks [:app:assembleDebug]
:app:preBuild
:app:compileDebugNdk
C:\Android\projects\hello-jni\app\build\intermediates\ndk\debug\obj/local/arm64-v8a/objs/hello-jni/C_\Android\projects\hello-jni\app\src\main\jni\hello-jni.o: In function `Java_com_example_hellojni_HelloJni_stringFromJNI':
hello-jni.c:(.text.Java_com_example_hellojni_HelloJni_stringFromJNI+0x24): undefined reference to `__android_log_write'
Error:error: ld returned 1 exit status
make.exe: *** [C:\Android\projects\hello-jni\app\build\intermediates\ndk\debug\obj/local/arm64-v8a/libhello-jni.so] Error 1
Error:Execution failed for task ':app:compileDebugNdk'.
> com.android.ide.common.internal.LoggedErrorException: Failed to run command:
C:\Android\android-ndk-r10c\ndk-build.cmd NDK_PROJECT_PATH=null APP_BUILD_SCRIPT=C:\Android\projects\hello-jni\app\build\intermediates\ndk\debug\Android.mk APP_PLATFORM=android-19 NDK_OUT=C:\Android\projects\hello-jni\app\build\intermediates\ndk\debug\obj NDK_LIBS_OUT=C:\Android\projects\hello-jni\app\build\intermediates\ndk\debug\lib APP_ABI=all
Error Code:
2
Output:
C:\Android\projects\hello-jni\app\build\intermediates\ndk\debug\obj/local/arm64-v8a/objs/hello-jni/C_\Android\projects\hello-jni\app\src\main\jni\hello-jni.o: In function `Java_com_example_hellojni_HelloJni_stringFromJNI':
hello-jni.c:(.text.Java_com_example_hellojni_HelloJni_stringFromJNI+0x24): undefined reference to `__android_log_write'
collect2.exe: error: ld returned 1 exit status
make.exe: *** [C:\Android\projects\hello-jni\app\build\intermediates\ndk\debug\obj/local/arm64-v8a/libhello-jni.so] Error 1
Information:BUILD FAILED
Information:Total time: 3.297 secs
Information:2 errors
Information:0 warnings
Information:See complete output in console
I've tried the suggestions given in this question, but I still get the same error: What is the Log API to call from an Android JNI program?
What am I doing wrong?
I'm using Android Studio 0.8.9 and NDK r10c.

Answer 1

I found an answer after a bit more searching.
If I build the .so files using the ndk-build script on the command line and add
sourceSets.main {
jni.srcDirs = []
jniLibs.srcDir 'src/main/libs'
}
into my build.gradle file so gradle doesn't try to build the .so files it all then works. Looks like a problem with Android Studio-Gradle-NDK integration?
I found the answer here https://stackoverflow.com/a/21111458/4182796

Answer 2

Ugly workaround is to remove function call and rebuild sources just add this after includes :
#if 1
#undef __android_log_print
#define __android_log_print(...) {}
#endif