Android Unsatisfied Link using gradle experimental

Question

I was trying to create a simple project to test the NDK in which a jnilib uses a prebuilt .so library but I keep getting an UnsatisfiedLink error:

With emulator:

java.lang.UnsatisfiedLinkError: dlopen failed: library "~/AndroidStudioProjects/HelloAndroidJni/app/src/main/jni/libs/dynamic/x86/libadd.so" not found

With actual device:

Caused by: java.lang.UnsatisfiedLinkError: Cannot load library: link_image[1891]:  1675 could not load needed library '~/AndroidStudioProjects/HelloAndroidJni/app/src/main/jni/libs/dynamic/armeabi/libadd.so' for 'libhello-android-jni.so' (load_library[1093]: Library '~/AndroidStudioProjects/HelloAndroidJni/app/src/main/jni/libs/dynamic/armeabi/libadd.so' not found)

The .so library has a single function "add" which adds 2 numbers. I compiled it with the NDK standalone toolchain for different ABI (doc):

add.c
#include "add.h"

int add(int x, int y){
    return x + y;
}

My jni (.c file):

#include <jni.h>
#include "add.h"


JNIEXPORT jint JNICALL
Java_com_example_tomas_helloandroidjni_MainActivity_addNumbersJni(JNIEnv *env, jobject instance,
                                                                  jint n1, jint n2) {

    return add(n1, n2);
}

My files structure looks like this:

And my gradle file (as defined in the experimental gradle guide):

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

model {

    repositories {
        libs(PrebuiltLibraries) {
            libadd{
                headers.srcDir "src/main/jni/prebuilts/include"
                binaries.withType(SharedLibraryBinary) {
                    sharedLibraryFile = file("src/main/jni/libs/dynamic/${targetPlatform.getName()}/libadd.so")

                }
            }
        }
    }

    android {
        compileSdkVersion = 23
        buildToolsVersion = "23.0.2"


        sources {
            main {
                jni {
                    dependencies {
                        library "libadd" linkage "shared"
                    }
                }
            }
        }

        ndk {
            moduleName = "hello-android-jni"
            debuggable = true
        }

        defaultConfig.with {
            applicationId = "com.example.tomas.helloandroidjni"
            minSdkVersion.apiLevel = 15
            targetSdkVersion.apiLevel = 23
            versionCode = 1
            versionName = "1.0"
        }

        buildTypes {
            release {
                minifyEnabled = false
                proguardFiles.add(file("proguard-android.txt"))

            }
        }

        productFlavors {
            create ("x86"){
                ndk.abiFilters.add("x86")
            }

            create("arm"){
                ndk.abiFilters.add("armeabi")
            }

            create("arm7"){
                ndk.abiFilters.add("armeabi-v7a")
            }
            create ("fat"){

            }
        }

    }

}

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    testCompile 'junit:junit:4.12'
    compile 'com.android.support:appcompat-v7:23.2.0'
}

I'm not sure where to look at, as I keep getting this error... Maybe I need to add a flag or something?

Thanks in advance for any advice!

EDIT 1.

I tried with static libraries and they work fine. As a consequence (of adding the static libs) I changed the folders' structure slightly (modifying the gradle file accordingly).

I'm working on both:

1. Actual device: Samsung GT-I8190L Android 4.1.2, API 16 - ARMv7 Processor rev 1 (v7l)
2. Emulator: Nexus 4 API 23 - x86

EDIT 2.

To compile the libraries I'm doing it with the NDK Standalone Toolchain:

1. Actual device (ARMv7): SYSROOT=$NDK/platforms/android-21/arch-arm and CC="$NDK/toolchains/arm-linux-androideabi-4.8/prebuilt/darwin-x86_64/bin/arm-linux-androideabi-gcc-4.8 --sysroot=$SYSROOT"

2. Emulator (x86): SYSROOT=$NDK/platforms/android-21/arch-x86 and CC="/Users/Tomas/Library/Android/android-ndk-r10e/toolchains/x86-4.8/prebuilt/darwin-x86_64/bin/i686-linux-android-gcc-4.8 --sysroot=$SYSROOT"

Answer 1

This may not be the way these native dependencies were expected to work, but (update: this is implicitly written in the doc!) even with plugin 0.7.0, gradle does not copy libadd.so to the APK. There is a workaround, though; add to build.gradle the enchantment:

model {
    android.sources.main {
        jniLibs.source.srcDir 'src/main/jni/libs/dynamic'
    }
}

Still, I recommend to move libs/dynamic folder out of the jni sources folder.