Question

I’m a newer to Android NDK.

There are 3 files, “first.c, first.h, second.c”
I want to compile to 2 shared libraries (libfirst.so, libsecond.so, the second one using the first one)

bellow is the Android.mk

LOCAL_PATH:= $(call my-dir)


# first lib
include $(CLEAR_VARS)

LOCAL_MODULE    := libtwolib-first
LOCAL_SRC_FILES := first.c

include $(BUILD_SHARED_LIBRARY)

# second lib
#
include $(CLEAR_VARS)

LOCAL_MODULE    := libtwolib-second
LOCAL_SRC_FILES := second.c

LOCAL_SHARED_LIBRARIES := libtwolib-first

include $(BUILD_SHARED_LIBRARY)

first.h

extern int first(int  x, int  y);

second.c

jint
Java_com_example_twolibs_TwoLibs_add( JNIEnv*  env,
                                      jobject  this,
                                      jint     x,
                                      jint     y )
{
    return first(x, y);
}

But when to run this program, the application is forced to shut down.
if first is compiled to static library. then it’s OK. Like the related Android.mk bellow:

LOCAL_PATH:= $(call my-dir)

# first lib, which will be built statically
#
include $(CLEAR_VARS)

LOCAL_MODULE    := libtwolib-first
LOCAL_SRC_FILES := first.c

include $(BUILD_STATIC_LIBRARY)

# second lib, which will depend on and include the first one
#
include $(CLEAR_VARS)

LOCAL_MODULE    := libtwolib-second
LOCAL_SRC_FILES := second.c

LOCAL_STATIC_LIBRARIES := libtwolib-first

include $(BUILD_SHARED_LIBRARY)

Can anyone help me?
Thanks a lot…

Answer 1

I’m pretty new to this myself, but as far as I know you can only have a single shared library. To use several libraries, link them statically, and then build a single shared one from the static ones.