Question

I’m trying to compilate my own library with the Android NDK But I’ve got some problems.

Here is my Android.mk file:

# Define vars for library that will be build statically.
include $(CLEAR_VARS)
LOCAL_MODULE     := MyLib
LOCAL_SRC_FILES  := ../../../src/mylib/utils/Timer.cpp
LOCAL_C_INCLUDES := ../../../src/mylib/

# Optional compiler flags.
LOCAL_LDLIBS     = -lz -lm
LOCAL_LDLIBS    := -llog  
LOCAL_CPPFLAGS  := -std=c++0x

include $(BUILD_SHARED_LIBRARY)

When I build my project with “ndk-build” I’ve got the following error :

Clean: mylib [armeabi]
Clean: stlport_shared [armeabi]
Clean: stlport_static [armeabi]
Compile++ thumb  : mylib <= Timer.cpp
jni/../../../src/mylib/utils/Timer.cpp:1:34: fatal error: mylib/utils/Timer.hpp: No such file or directory
compilation terminated.

For information, I’m including the .hpp like that :

#include <mylib/utils/Timer.hpp>

I don’t know why headers aren’t found, my library working in Xcode and eclipse.
Thanks for your time!

Edit: Here is my project’s architecture to understand my problem: https://i.stack.imgur.com/wrcAC.jpg
I’m trying to indicate where is located my “.hpp” files in the Android.mk file.

Answer 1

Your LOCAL_C_INCLUDES should include the ../../../src/ or ../../../inc directory in order for you to use #include <mylib/utils/Timer.hpp> i.e:

LOCAL_C_INCLUDES := ../../../src/

Why don’t you put your C and C++ headers and source files inside the jni/ directory of the Android project, near the Android.mk file?

See: What is the difference between #include <filename> and #include "filename"?

Also this is incorrect, because the second LOCAL_LDLIBS overrides the previous LOCAL_LDLIBS directive in the current module :

LOCAL_LDLIBS     = -lz -lm
LOCAL_LDLIBS    := -llog  

If you want to append to a make directive use:

LOCAL_LDLIBS    := -lz -lm
LOCAL_LDLIBS    += -llog 

or LOCAL_LDLIBS := -lz -lm -llog

EDIT:
Using the following Android.mk it seems to work if you run ndk-build from the Android/jni directory.

LOCAL_PATH := $(call my-dir)

# first lib, which will be built statically
#
include $(CLEAR_VARS)
LOCAL_MODULE     := MyLib
LOCAL_C_INCLUDES := ../../../inc/
LOCAL_SRC_FILES  := ../../../src/mylib/utils/Timer.cpp
include $(BUILD_STATIC_LIBRARY)

# second lib, which will depend on and include the first one
#
include $(CLEAR_VARS)
LOCAL_MODULE    := MyNativeFinalSharedLib
LOCAL_LDLIBS    := -lz -lm -llog  
LOCAL_CPPFLAGS  := -std=c++0x
LOCAL_STATIC_LIBRARIES := MyLib   
include $(BUILD_SHARED_LIBRARY)

Also you forgot to put LOCAL_PATH := (call my-dir) on the first line and some other missing make directives.

An Android.mk file must begin with the definition of the LOCAL_PATH
variable. It is used to locate source files in the development tree.
In this example, the macro function ‘my-dir’, provided by the build
system, is used to return the path of the current directory (i.e. the
directory containing the Android.mk file itself).

(from android-ndk-r8d/docs/ANDROID-MK.html)