title: Crash on MediaController.show()
body: <p>i've a problem with mediacontroller, this part of code works perfecty on different devices as Acer Liquid (gingerbread), Archos 43 (froyo) e Archos 32 (froyo)...</p>
  
  <pre><code>VideoView videoView = (VideoView) findViewById(R.id.videoView1);
  MediaController mediaController = new MediaController(this);
  mediaController.setAnchorView(videoView); 
  File filevideo = new File(Environment.getExternalStorageDirectory() + "/edizionitsm/firenze/map_" + map_n + "/",filename + "_" + language + ".mp4");
  Uri video = Uri.fromFile(filevideo);
  videoView.setMediaController(mediaController);
  videoView.setVideoURI(video);
  videoView.start();
  </code></pre>
  
  <p>...but on a Point of View Pro Tab2 (gingerbread) it crash at the beginning of the activity.</p>
  
  <pre><code>11-09 14:12:59.640: E/AndroidRuntime(31433): FATAL EXCEPTION: main
  11-09 14:12:59.640: E/AndroidRuntime(31433): java.lang.RuntimeException: Unable to start activity ComponentInfo{edizionitsm.archeoplayer/edizionitsm.archeoplayer.Player}: java.lang.NullPointerException
  11-09 14:12:59.640: E/AndroidRuntime(31433):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
  11-09 14:12:59.640: E/AndroidRuntime(31433):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
  11-09 14:12:59.640: E/AndroidRuntime(31433):    at android.app.ActivityThread.access$1500(ActivityThread.java:117)
  11-09 14:12:59.640: E/AndroidRuntime(31433):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
  11-09 14:12:59.640: E/AndroidRuntime(31433):    at android.os.Handler.dispatchMessage(Handler.java:99)
  11-09 14:12:59.640: E/AndroidRuntime(31433):    at android.os.Looper.loop(Looper.java:123)
  11-09 14:12:59.640: E/AndroidRuntime(31433):    at android.app.ActivityThread.main(ActivityThread.java:3683)
  11-09 14:12:59.640: E/AndroidRuntime(31433):    at java.lang.reflect.Method.invokeNative(Native Method)
  11-09 14:12:59.640: E/AndroidRuntime(31433):    at java.lang.reflect.Method.invoke(Method.java:507)
  11-09 14:12:59.640: E/AndroidRuntime(31433):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
  11-09 14:12:59.640: E/AndroidRuntime(31433):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
  11-09 14:12:59.640: E/AndroidRuntime(31433):    at dalvik.system.NativeStart.main(Native Method)
  11-09 14:12:59.640: E/AndroidRuntime(31433): Caused by: java.lang.NullPointerException
  11-09 14:12:59.640: E/AndroidRuntime(31433):    at android.widget.MediaController.disableUnsupportedButtons(MediaController.java:640)
  11-09 14:12:59.640: E/AndroidRuntime(31433):    at android.widget.MediaController.show(MediaController.java:674)
  11-09 14:12:59.640: E/AndroidRuntime(31433):    at android.widget.MediaController.show(MediaController.java:631)
  11-09 14:12:59.640: E/AndroidRuntime(31433):    at android.widget.VideoView.start(VideoView.java:962)
  11-09 14:12:59.640: E/AndroidRuntime(31433):    at edizionitsm.archeoplayer.Player.onCreate(Player.java:48)
  11-09 14:12:59.640: E/AndroidRuntime(31433):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
  11-09 14:12:59.640: E/AndroidRuntime(31433):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
  11-09 14:12:59.640: E/AndroidRuntime(31433):    ... 11 more
  </code></pre>
  
  <p>the problem is in the function show() of mediacontroller class. How can i resolve it?
  Thank you.</p>