Question

I’ve built the Assimp library as a shared library. I’ve included it in my Android ndk project and it builds fine but when I load it I get the following error:
Unable to load native library: My-Native-Activity.

(Perhaps I should add that my activity works fine when the library is not included and that I’ve checked the apk and on the device; the library is being added to the libs folder and installed on the device in /data/data/my-app/lib.)

I’ve done a lot of reading and it seems that the only way to solve this is to load them using System.loadLibrary before launching my native activity. I think I’d prefer load them dynamically using dlopen before taking that approach.

Am I correct in assuming that Android wont automatically load the shared libraries my native activity(i.e. my shared library) depends on?

I would build it as a static library but it was over 54Mb which wont work.

This is my Android.mk:
I’ve tried adding -lassimp to LOCAL_LDLIBS. I’m not sure if that would be correct but it didn’t make any difference.

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)
LOCAL_MODULE                        := assimp
LOCAL_SRC_FILES                     := libassimp.so
include $(PREBUILT_SHARED_LIBRARY)

include $(CLEAR_VARS)
LOCAL_MODULE                        := native-activity
LOCAL_SRC_FILES                     := main.cpp 
LOCAL_LDLIBS                        := -llog -landroid -lEGL -lGLESv2 
LOCAL_STATIC_LIBRARIES              := android_native_app_glue
LOCAL_SHARED_LIBRARIES              := assimp
LOCAL_CPPFLAGS                      += -march=armv7-a -mfloat-abi=softfp
LOCAL_CFLAGS                := $(LOCAL_CPPFLAGS)
TARGET_ARCH_ABI                     := armeabi-v7a
LOCAL_C_INCLUDES            += $(LOCAL_PATH)
include $(BUILD_SHARED_LIBRARY)

$(call import-module,android/native_app_glue)

Answer 1

Subclassing android.app.NativeActivity is the simplest way to solve this problem.

package com.you;

public class MyNativeActivity extends android.app.NativeActivity {

    static {
       System.loadLibrary("assimp");
    }
 }

Then change your AndroidManifest.xml. Replace android.app.NativeActivity with MyNativeActivity and remove the tag hasCode="false".

As a side note, Android does search for dependencies when loading a shared library. But the scope of the search is limited to /system/lib.