title: How do I add more to JNI interface
body: <p>I followed a tutorial and built a JNI interface in Android studio. But I don't know how to add more to it by calling other functions in my C library. I am not even sure if I can see my library yet; I figure if I call one of the functions I would know. So my question is I do not understand the file in my JNI folder. I see it is written in C. Why is the #include different from the usual C includes I have seen which is something like #include  or I believe you can also say #include "foo.c" also? Why are there _'s in the package names? How do I call a function in one of my libraries two levels below the JNI folder? I read the JNI specification and still don't understand how JNIenv works.  </p>
  
  <p>For example, just to test this, I tried adding random.c to my file. It is located two levels below my JNI folder; ndk-builder says there is no such file. So I think I need to work on my Andorid.mk and make sure the build environment has visibility to random.c. Is that true? Can I somehow specify the fully qualified path to random.c? </p>
  
  <pre><code>#include "com_example_sansari_ndktest_MainActivity.h"
  #include &lt;random.c&gt;
  
   JNIEXPORT jstring JNICALL  
   Java_com_example_sansari_ndktest_MainActivity_HelloJNI
     (JNIEnv *env, jobject obj)
  {
   (*env)-&gt;NewStringUTF(env,"Hi From Sean");
  }
  </code></pre>
  
  <p>@JP; Thanks. So I should be able to say something like the following in the above file: </p>
  
  <p>(*env)->random();</p>
  
  <p>And be able to receive an integer in my main activity? random() declares a static integer, modifies it, and returns it. </p>
  
  <p>@JP. Thanks. so I can say 
  random(); in my C file, and the value would show up in my MainActivity. Well that is good news; thanks. Now i gota figure out how to fix my Andorid.mk.</p>
  
  <p>@JP. Thanks. i took it out. I really appreciate all your help.</p>