System loadLibrary couldn t find native library in my case

Question

I want to use a existing native library from another Android project  so I just copied the NDK built library  libcalculate so  to my new Android project  In my new Android project I created a folder libs armeabi  and put libcalculate so there  There is no jni  folder  My testing device has ARM architecture   In my java code I load the library by     static      System loadLibrary  calculate          When I run my new android project  I got error   java lang UnsatisfiedLinkError       nativeLibraryDirectories   vendor lib   system lib    couldn t find  libcalculate so    So  as error says  the copied native library is not in  verdor lib or  system lib   how to resolve this problem in my case    I unziped the apk package  under lib  there is libcalculate so       UPDATE       I also tried to create a jni  folder under project root  and add an Android mk file under jni   The content of Android mk is   LOCAL PATH      call my-dir   include   CLEAR VARS  LOCAL MODULE       libcalculate LOCAL SRC FILES    libcalculate so include   PREBUILT SHARED LIBRARY    Then  under project root  I executed ndk-build   After that  the armeabi  and armeabi-v7a  directories are generated by ndk-build  with libcalculate so inside the folder    Then I run my maven build the project successfully  In the final apk package  there are   lib armeabi libcalculate so lib armeabi-v7a libcalculate so   But when I run my app  the same error throw   java lang UnsatisfiedLinkError       nativeLibraryDirectories   vendor lib   system lib    couldn t find  libcalculate so

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This is an Android 8 update   In earlier version of Android  to LoadLibrary native shared libraries  for access via JNI for example  I hard-wired my native code to iterate through a range of potential directory paths for the lib folder  based on the various apk installation upgrade algorithms    data data  lt PackageName gt  lib  data app-lib  lt PackageName gt -1 lib  data app-lib  lt PackageName gt -2 lib  data app  lt PackageName gt -1 lib  data app  lt PackageName gt -2 lib   This approach is hokey and will not work for Android 8  from https   developer android com about versions oreo android-8 0-changes html you ll see that as part of their  Security  changes you now need to use sourceDir    You can no longer assume that APKs reside in directories whose names end in -1 or -2  Apps should use sourceDir to get the directory  and not rely on the directory format directly    Correction  sourceDir is not the way to find your native shared libraries  use something like  Tested for Android 4 4 4 --  8 0     Return Full path to the directory where native JNI libraries are stored  private static String getNativeLibraryDir Context context        ApplicationInfo appInfo   context getApplicationInfo        return appInfo nativeLibraryDir

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For reference  I had this error message and the solution was that when you specify the library you miss the  lib  off the front and the   so  from the end   So  if you have a file libmyfablib so  you need to call      System loadLibrary  myfablib       this loads the file  libmyfablib so     Having looked in the apk  installed uninstalled and tried all kinds of complex solutions I couldn t see the simple problem that was right in front of my face

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To root cause  and maybe solve your issue in the same time   here is what you can do    Remove the jni folder and all the  mk files  You don t need these nor the NDK if you aren t compiling anything  Copy your libcalculate so file inside  lt project gt  libs  armeabi armeabi-v7a x86        When using Android Studio  it s  lt project gt  app src main jniLibs  armeabi armeabi-v7a x86       but I see you re using eclipse  Build your APK and open it as a zip file  to check that your libcalculate so file is inside lib  armeabi armeabi-v7a x86       Remove and install your application Run dumpsys package packages   grep yourpackagename to get the nativeLibraryPath or legacyNativeLibraryDir of your application  Run ls on the nativeLibraryPath you had or on legacyNativeLibraryDir armeabi  to check if your libcalculate so is indeed there  If it s there  check if it hasn t been altered from your original libcalculate so file  is it compiled against the right architecture  does it contain the expected symbols  are there any missing dependencies  You can analyze libcalculate so using readelf    In order to check step 5-7  you can use my application instead of command lines and readelf  Native Libs Monitor  PS  It s easy to get confused on where  so files should be put or generated by default  here is a summary    libs CPU ABI inside an eclipse project jniLibs CPU ABI inside an Android Studio project jni CPU ABI inside an AAR lib CPU ABI inside the final APK inside the app s nativeLibraryPath on a  lt 5 0 device  and inside the app s legacyNativeLibraryDir CPU ARCH on a   5 0 device    Where CPU ABI is any of  armeabi  armeabi-v7a  arm64-v8a  x86  x86 64  mips  mips64  Depending on which architectures you re targeting and your libs have been compiled for    Note also that libs aren t mixed between CPU ABI directories  you need the full set of what you re using  a lib that is inside the  armeabi folder will not be installed on a armeabi-v7a device if there are any libs inside the armeabi-v7a folder from the APK

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Try to call your library after include PREBUILT SHARED LIBRARY section   LOCAL PATH      call my-dir   include   CLEAR VARS  LOCAL MODULE       libcalculate LOCAL SRC FILES     lt PATH gt  libcalculate so include   PREBUILT SHARED LIBRARY         LOCAL SHARED LIBRARIES    libcalculate   Update   If you will use this library in Java you need compile it as shared library  LOCAL PATH      call my-dir   include   CLEAR VARS  LOCAL MODULE       libcalculate LOCAL SRC FILES     lt PATH gt  libcalculate so include   BUILD SHARED LIBRARY    And you need deploy the library in the  vendor lib directory

User · Answer

defaultConfig   ndk               abiFilters  quot armeabi-v7a quot    quot x86 quot    quot armeabi quot    quot mips quot           Just add these line in build gradle app level

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In my experience  in an armeabi-v7a mobile  when both armeabi and armeabi-v7a directories are present in the apk  the  so files in armeabi directory won t be linked  although the  so files in armeabi WILL be linked in the same armeabi-v7a mobile  if armeabi-v7a is not present

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actually  you can t just put a  so file in the  libs armeabi  and load it with System loadLibrary  You need to create an Android mk file and declare a prebuilt module where you specify your  so file as a source   To do so  put your  so file and the Android mk file in the jni folder  Your Android mk should look something like that   LOCAL PATH      call my-dir   include   CLEAR VARS  LOCAL MODULE       libcalculate LOCAL SRC FILES    libcalculate so include   PREBUILT SHARED LIBRARY    Source   Android NDK documentation about prebuilt

User · Answer

Are you using gradle  If so put the  so file in  lt project gt  src main jniLibs armeabi   I hope it helps

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In gradle  after copying all files folders to libs   jniLibs srcDirs     libs     Adding the above line to sourceSets in build gradle file worked  Nothing else worked whatsoever

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The reason for this error is because there is a mismatch of the ABI between your app and the native library you linked against  Another words  your app and your  so is targeting different ABI   if you create your app using latest Android Studio templates  its probably targeting the arm64-v8a but your  so may be targeting armeabi-v7a for example   There is 2 way to solve this problem    build your native libraries for each ABI your app support  change your app to target older ABI that your  so built against    Choice 2 is dirty but I think you probably have more interested in   change your app s build gradle  android       defaultConfig                       ndk               abiFilters  armeabi-v7a

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In my case i must exclude compiling sources by gradle and set libs path  android                sourceSets                       main jni srcDirs              main jniLibs srcDirs     libs

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please add all suport  app build gradle  ndk           moduleName  serial port          ldLibs  log    z    m          abiFilters  arm64-v8a   armeabi    armeabi-v7a    x86   x86 64   mips   mips64      app src jni Application mk  APP ABI    arm64-v8a armeabi armeabi-v7a x86 x86 64 mips mips64

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You could just change ABI to use older builds   defaultConfig                ndk           abiFilters  armeabi-v7a                    You should also use deprecated NDK by adding this line to gradle properties   android useDeprecatedNdk true

[android] System.loadLibrary(...) couldn't find native library in my case

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