Allow the user to change the track

This is an example of how you could create a button that allows a user to select a closed-caption track.

1. Create a simple button to change the closed-caption track.

   <Button
     android:id="@+id/selectCC"
     android:layout_width="wrap_content"
     android:layout_height="wrap_content"
     android:layout_alignParentBottom="true"
     android:layout_alignParentRight="true"
     android:layout_marginRight="10dp"
     android:onClick="selectClosedCaptioningClick"
     android:text="CC" />
   

2. Convert the list of available closed caption tracks to a string array. The closed-caption tracks that have activity (data was discovered for that channel) are marked accordingly:

   /**
   * Converts the closed captions tracks to a string array.
   *
   * @return array of CC tracks
   */
   private String[] getCCsAsArray() {
     List<String> closedCaptionsTracksAsStrings = new ArrayList<String>();
    MediaPlayerItem currentItem = mediaPlayer.getCurrentItem();
    if (currentItem != null) {
         List<ClosedCaptionsTrack> closedCaptionsTracks =
              currentItem.getClosedCaptionsTracks();
        Iterator<ClosedCaptionsTrack> iterator = closedCaptionsTracks.iterator();
       while (iterator.hasNext()) {
             ClosedCaptionsTrack closedCaptionsTrack = iterator.next();
             String isActive = closedCaptionsTrack.isActive() ? " (" +    getString(R.string.active)+ ")" : "";
           closedCaptionsTracksAsStrings.add(closedCaptionsTrack.getName() + isActive);
         }
     }
     return closedCaptionsTracksAsStrings.toArray(new
         String[closedCaptionsTracksAsStrings.size()]);
   }
   

3. When the user clicks the button, display a dialog that shows all the default CC tracks.

   public void selectClosedCaptioningClick(View view) {
     Log.i(LOG_TAG + "#selectClosedCaptions", "Displaying closed captions chooser dialog.");
     final String items[] = getCCsAsArray();
     final AlertDialog.Builder ab = new AlertDialog.Builder(this);
     ab.setTitle(R.string.PlayerControlCCDialogTitle);
     ab.setSingleChoiceItems(items, selectedClosedCaptionsIndex, new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int whichButton) {
           // Select the new closed captioning track.
           MediaPlayerItem currentItem = mediaPlayer.getCurrentItem();
           ClosedCaptionsTrack desiredClosedCaptionsTrack = currentItem.getClosedCaptionsTracks().get(whichButton);
           boolean result = currentItem.selectClosedCaptionsTrack(desiredClosedCaptionsTrack);
           if (result) {
              	selectedClosedCaptionsIndex = whichButton;
           }
           // Dismiss dialog.
           dialog.cancel();
        }
     }).setNegativeButton(R.string.PlayerControlCCDialogCancel, new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int whichButton) {
           // Just cancel the dialog.
        }
     });
     ab.show();
   }