title: How to add "jni/*.c/cpp" files to CMakeLists.txt file?
body: <p>I have created a new project including c++ ndk. So it automatically created a <code>CMakeLists.txt</code> file and a <code>cpp</code> directory. But When I created a new directory named <code>jni</code> and tried to put <code>test.c</code>, <code>Android.mk</code> and <code>Application.mk</code> files on it, I got this error message when I wanted to sync my project:</p>
  
  <blockquote>
    <p>This file is not part of the proejct.please include it to appropriaten
    build file</p>
  </blockquote>
  
  <p>Android.mk :</p>
  
  <pre><code>LOCAL_PATH := $(call my-dir)
  include $(CLEAR_VARS)
  LOCAL_MODULE := ndktest
  LOCAL_SRC_FILES := test.c
  </code></pre>
  
  <p>Application.mk :</p>
  
  <pre><code>APP_ABI := all
  </code></pre>
  
  <p>test.c :</p>
  
  <pre><code>#include &lt;jni.h&gt;
  #include &lt;string.h&gt;
  
  extern "C"
  JNIEXPORT jstring JNICALL
  Java_com_example_m_ndktest_MainActivity_testJNI(JNIEnv *env, jobject instance)
  {
      return env-&gt;NewStringUTF(hello.c_str());
  
  }
  
  JNIEXPORT jstring JNICALL
  Java_com_example_m_ndktest_MainActivity_testJNI2(JNIEnv *env, jobject instance)
  {
      return (*env)-&gt;NewStringUTF(env, "hellooooo");
  
  }
  </code></pre>
  
  <p>How should I include my <code>.mk</code> files inside the <code>CMakeLists.txt</code> ?</p>
  
  <p>CMakeLists.txt :</p>
  
  <pre><code># For more information about using CMake with Android Studio, read the
  # documentation: https://d.android.com/studio/projects/add-native-code.html
  
  # Sets the minimum version of CMake required to build the native library.
  
  cmake_minimum_required(VERSION 3.4.1)
  
  # Creates and names a library, sets it as either STATIC
  # or SHARED, and provides the relative paths to its source code.
  # You can define multiple libraries, and CMake builds them for you.
  # Gradle automatically packages shared libraries with your APK.
  
  add_library( # Sets the name of the library.
               native-lib
  
               # Sets the library as a shared library.
               SHARED
  
               # Provides a relative path to your source file(s).
               src/main/cpp/native-lib.cpp )
  
  # Searches for a specified prebuilt library and stores the path as a
  # variable. Because CMake includes system libraries in the search path by
  # default, you only need to specify the name of the public NDK library
  # you want to add. CMake verifies that the library exists before
  # completing its build.
  
  find_library( # Sets the name of the path variable.
                log-lib
  
                # Specifies the name of the NDK library that
                # you want CMake to locate.
                log )
  
  # Specifies libraries CMake should link to your target library. You
  # can link multiple libraries, such as libraries you define in this
  # build script, prebuilt third-party libraries, or system libraries.
  
  target_link_libraries( # Specifies the target library.
                         native-lib
  
                         # Links the target library to the log library
                         # included in the NDK.
                         ${log-lib} )
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/sOk1K.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/sOk1K.png" alt="enter image description here"></a></p>
  
  <blockquote>
    <p>***Also I have a question, where can I find the tutorial about the STRANGE syntax that we should write in Android-ndk? (I mean the test.c
    syntax that I copied from the default <code>native-lib.c</code>)</p>
  </blockquote>