CODEWITHSUNDEEP
androidc++candroid-studionative
Jolopy
Jolopy

Reputation: 92

Android: Linking a external static C/C++ Library in Android Studio

I've seen many answers to get Native Code working in Android Studio with using Cmake however, not many answers on how to include a pre-compiled C/C++ library into Android. Here are the steps I've taken to try and get a Native Library(trying first with .a) to work.

1) mylib.c is my C library I want to import into Android Studio

#include "mylib.h"


    int total_foo;

    int foo(float y, float z) { 
    total_foo = y + z;
    return total_foo;

    }

2) mylib.h is the header file for mylib.c

#ifndef _MYLIB_H_
#define _MYLIB_H_

    #define MAX_FOO  20

        struct foo_struct {  
        int x;
        float y;
    };
    typedef struct foo_struct foo_struct;

    extern int total_foo;   

    extern int foo(float y, float z); 

#endif

3) Command for .o file (using NDK with make_standalone_toolchain.py)

$CC -o mylib.o -c mylib.c

4) Command for .a file

ar rcs mylib.a mylib.o

5) Create a Native C++ Project

Now this is where I am stuck. I've created the Android Studio project with Native C++ support and need to figure out where to put my pre-compiled mylib.a file to be able to make the function call "foo". I seen all different types of places like the jniLibs folder , libs , and cpp folder. But no examples of what to do after. Like adding the Native Library into the Gradle.

*Putting the code into Android Studio and using Cmake is out since I will only have a Static Library file. *

TLDR: How to add a pre-compiled *.a file into Android Studio.

Upvotes: 4

Views: 4332

Answers (1)

Michael
Michael

Reputation: 58517

Assuming that you have a mylib.a somewhere that was built with the NDK, you can link against it in your main shared library like this:

CMakeLists.txt:

cmake_minimum_required(VERSION 3.4.1)

add_library(native-main-lib SHARED src/main/cpp/native-lib.cpp)

add_library(my_lib STATIC IMPORTED)
set_target_properties(my_lib PROPERTIES IMPORTED_LOCATION path/to/mylib.a)
set_target_properties(my_lib PROPERTIES INCLUDE_DIRECTORIES path/to/mylib/include)

target_link_libraries(native-main-lib my_lib)

Upvotes: 8

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