Set final variables where applicable

Author: jadkik

app/src/main/java/org/schabi/newpipe/fragments/detail/VideoDetailFragment.java

@@ -696,7 +696,7 @@ public boolean onOptionsItemSelected(final MenuItem item) {
                 return true;
             case R.id.menu_item_share_stream:
                 if (currentInfo != null) {
-                    Stream stream;
+                    final Stream stream;
                     if (currentInfo.getVideoStreams().isEmpty()
                             && currentInfo.getVideoOnlyStreams().isEmpty()) {
                         stream = getDefaultAudioStream();
@@ -939,9 +939,9 @@ private boolean shouldShowComments() {
     //////////////////////////////////////////////////////////////////////////*/
 
     private void openBackgroundPlayer(final boolean append) {
-        AudioStream audioStream = getDefaultAudioStream();
+        final AudioStream audioStream = getDefaultAudioStream();
 
-        boolean useExternalAudioPlayer = PreferenceManager.getDefaultSharedPreferences(activity)
+        final boolean useExternalAudioPlayer = PreferenceManager.getDefaultSharedPreferences(activity)
                 .getBoolean(activity.getString(R.string.use_external_audio_player_key), false);
 
         if (!useExternalAudioPlayer && android.os.Build.VERSION.SDK_INT >= 16) {
@@ -1033,9 +1033,8 @@ private VideoStream getSelectedVideoStream() {
      *
      * @return AudioStream instance according to user settings
      */
-    @Nullable
     private AudioStream getDefaultAudioStream() {
-        int streamIndex = ListHelper.getDefaultAudioFormat(activity, currentInfo.getAudioStreams());
+        final int streamIndex = ListHelper.getDefaultAudioFormat(activity, currentInfo.getAudioStreams());
         return currentInfo.getAudioStreams().get(streamIndex);
     }