Cannot print log messages from JNI with Android Studio

Question

The error I get is:

error: undefined link to '__android_log_print'

I have already added this line to my .cpp file:

#include <android/log.h> 

I tried with both: __ android_log_print and __ android_log_write

I also contacted the logging library in my Android.mk file (which I manually compile).

LOCAL_LDLIBS: = -llog

I also tried several alternatives that I found:

 LOCAL_LDLIBS := -L$(SYSROOT)/usr/lib -llog 

Here is my Android.mk:

 LOCAL_PATH := $(call my-dir) #used to skip re-compiling libraw #include $(CLEAR_VARS) #LOCAL_MODULE := libraw_r #LOCAL_SRC_FILES := ../obj/local/armeabi/libraw_r.so #LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/libraw #include $(PREBUILT_SHARED_LIBRARY) #used for compiling libraw include $(CLEAR_VARS) LOCAL_CFLAGS += -I$(SYSROOT)/usr/lib/include/libraw -pthread -w LOCAL_CXXFLAGS += -I$(SYSROOT)/usr/lib/include/libraw -pthread -w LOCAL_MODULE := libraw_r # name of your module LOCAL_LDLIBS += -L$(SYSROOT)/usr/lib -lstdc++ # libraries to link against, lstdc++ is auto-linked LOCAL_SRC_FILES := internal/dcraw_common.cpp internal/dcraw_fileio.cpp internal/demosaic_packs.cpp src/libraw_cxx.cpp src/libraw_c_api.cpp LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/libraw include $(BUILD_SHARED_LIBRARY) include $(CLEAR_VARS) LOCAL_MODULE := armapi LOCAL_SRC_FILES := armapi.cpp LOCAL_SHARED_LIBRARIES := libraw_r include $(BUILD_SHARED_LIBRARY) LOCAL_LDLIBS := -L$(SYSROOT)/usr/lib -llog 

And here is the build.gradle file:

 buildscript { repositories { mavenCentral() } dependencies { classpath 'com.android.tools.build:gradle:1.0.0+' } } apply plugin: 'android' dependencies { compile fileTree(dir: 'libs', include: '*.jar') } android { compileSdkVersion 21 buildToolsVersion "21.1.2" defaultConfig { ndk { moduleName "armapi" ldLibs "log" } } sourceSets { main { manifest.srcFile 'AndroidManifest.xml' jniLibs.srcDir 'libs' // use the jni .so compiled from the manual ndk-build command jni.srcDirs = [] //disable automatic ndk-build call java.srcDirs = ['src'] resources.srcDirs = ['src'] aidl.srcDirs = ['src'] renderscript.srcDirs = ['src'] res.srcDirs = ['res'] assets.srcDirs = ['assets'] } // Move the tests to tests/java, tests/res, etc... instrumentTest.setRoot('tests') // Move the build types to build-types/<type> // For instance, build-types/debug/java, build-types/debug/AndroidManifest.xml, ... // This moves them out of them default location under src/<type>/... which would // conflict with src/ being used by the main source set. // Adding new build types or product flavors should be accompanied // by a similar customization. debug.setRoot('build-types/debug') release.setRoot('build-types/release') } } 

Answer 1

It seems that using Gradle + Android Studio, the Android.mk file is ignored .

As described here , try adding the following directive to your build.gradle:

 android { defaultConfig { ndk { moduleName "modulename" ldLibs "log" } } } 

Answer 2

Add this to your android.mk file

LOCAL_LDLIBS: = -llog -ljnigraphics

Answer 3

I am using Gradle 2.5 with Android Studio 1.4.1, and it works for me with this syntax:

  ldLibs + = "log" 

The build.gradle model should be something similar:

 apply plugin: 'com.android.model.application'

     model {
         android {
             compileSdkVersion = 23
             buildToolsVersion = "23.0.1"

             defaultConfig.with {
                 applicationId = "com.local.some.project"
                 minSdkVersion.apiLevel = 17
                 targetSdkVersion.apiLevel = 23
                 versionCode = 1
                 versionName = "1.0"
             }
         }

         android.buildTypes {
             release {
                 minifyEnabled = false
                 proguardFiles + = file ('proguard-rules.pro')
             }
         }

         android.ndk {
             moduleName = "MyModel"
             ldLibs + = "log"
         }

         compileOptions.with {
             sourceCompatibility = JavaVersion.VERSION_1_7
             targetCompatibility = JavaVersion.VERSION_1_7
         }
     }

     dependencies {
         compile fileTree (include: ['* .jar'], dir: 'libs')
         compile 'com.android.support:appcompat-v7:23.0.1'
         compile files ('libs / some3rdParty.jar')
     }