code: public void animateContentViewRotationY(float degree, float alpha,
                                              Animator.AnimatorListener listener,
                                              int duration) {
  
          if (DBG) Log.v(TAG, "animateContentViewRotationY - " +
                         "degree=" + degree + ", alpha=" + alpha);
  
          mContentView.animate().cancel();
          mContentView.animate()
              .alpha(alpha)
              .rotationY(degree)
              .setListener(listener)
              .setDuration(duration)
              .start();
      }
docs: Rotate the contentView to y degree with animation.
  
  @param degree
  @param alpha
  @param listener
  @param duration