title: Generating header file with JNI using 'javah'
body: <p>I'm trying to use JNI for an Android application using the OpenCV4Android library. I can generate a header file without using the opencv library, but I get an error whenever the class imports anything. I assume it needs to link to the library, but I'm not sure how to do that? I'm using cygwin on a Windows 8.1 64 bit machine. </p>
  
  <p>original output:</p>
  
  <pre><code>$ javah -jni -classpath ./bin/classes -d jni/ com.example.icam.nativeRDE  
  Error: Class org.opencv.core.Mat could not be found.
  </code></pre>
  
  <p>After following advice from: <a href="https://stackoverflow.com/questions/13438368/android-generate-jni-header-files-with-javah-show-error-that-cant-find-org-o">Android, generate jni Header Files with javah , show error that can&#39;t find org.opencv.core.Mat</a>, I get the following output:</p>
  
  <pre><code>$ javah -classpath /cygdrive/c/Users/Majid/Documents/OpenCV4Android/OpenCVLib2.4.8/bin/classes/org/opencv/;/cygdrive/c/Users/Majid/Documents/OpenCV4Android/iCam/bin/classes/com/example/icam/ -jni -d jni/ com.example.icam.nativeRDE
  Error: no classes specified
  -bash: /cygdrive/c/Users/Majid/Documents/OpenCV4Android/iCam/bin/classes/com/example/icam/: is a directory
  </code></pre>
  
  <p>I've tried:</p>
  
  <ul>
  <li>removing '/' after icam</li>
  <li>adding nativeRDE after 'icam/' </li>
  <li>adding nativeRDE.class after 'icam/'</li>
  </ul>
  
  <p>Thanks for any help.</p>