public void logout() {
   controller.logout();
   deleteSharedPReferences();
   Intent login = new Intent(getActivity(), LoginActivity.class);
   Utils.cleanBackStack(login);
   startActivity(login);
 }
  @Override
  public View onCreateView(
      LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.fragment_profile, container, false);

    // username from current user
    username = (TextView) view.findViewById(R.id.username);
    username.setText(controller.getUsername());

    photosNumber = (TextView) view.findViewById(R.id.photos_number);
    photosNumber.setText(controller.getPhotosNumber());
    albumsNumber = (TextView) view.findViewById(R.id.albums_number);
    albumsNumber.setText(controller.getPhotosNumber());
    friendsNumber = (TextView) view.findViewById(R.id.friends_number);
    friendsNumber.setText(controller.getFriendsNumber());

    // profile picture
    profilePicture = (ImageView) view.findViewById(R.id.profilePicture);
    // download profile picture from Parse
    Bitmap picture = controller.getProfilePicture();
    if (picture != null) profilePicture.setImageBitmap(picture);
    // register the context menu to set profile picture
    registerForContextMenu(profilePicture);

    mProgressBar = (ProgressBar) view.findViewById(R.id.progressBarChangeProfilePicture);

    // logout
    buttonLogOut = (Button) view.findViewById(R.id.button_logout);
    buttonLogOut.setOnClickListener(
        new OnClickListener() {
          public void onClick(View v) {
            logout();
          }
        });
    return view;
  }