private void reflectMemberVariablesInLeftButton(){
  final boolean lastPageReached=(viewPager.getCurrentItem() + 1) == pages.size();
  final boolean buttonShouldBeInvisible=(lastPageReached && disableLeftButtonOnLastPage) || leftButtonDisabled;
  final boolean buttonIsCurrentlyInvisible=leftButton.getVisibility() == View.INVISIBLE;
  final boolean shouldUpdateButton=buttonShouldBeInvisible != buttonIsCurrentlyInvisible;
  if (shouldUpdateButton) {
    final Animator buttonAnimator=buttonShouldBeInvisible ? buttonAnimatorFactory.newLeftButtonDisappearAnimator(leftButton) : buttonAnimatorFactory.newLeftButtonAppearAnimator(leftButton);
    if (buttonShouldBeInvisible) {
      disableButton(buttonAnimator,leftButton);
    }
 else {
      enableButton(buttonAnimator,leftButton);
    }
  }
}

private void reflectMemberVariablesInLeftButton ( ) { final boolean lastPageReached = ( viewPager . getCurrentItem ( ) + 1 ) == pages . size ( ) ; final boolean buttonShouldBeInvisible = ( lastPageReached && disableLeftButtonOnLastPage ) || leftButtonDisabled ; final boolean buttonIsCurrentlyInvisible = leftButton . getVisibility ( ) == View . INVISIBLE ; final boolean shouldUpdateButton = buttonShouldBeInvisible != buttonIsCurrentlyInvisible ; if ( shouldUpdateButton ) { final Animator buttonAnimator = buttonShouldBeInvisible ? buttonAnimatorFactory . newLeftButtonDisappearAnimator ( leftButton ) : buttonAnimatorFactory . newLeftButtonAppearAnimator ( leftButton ) ; if ( buttonShouldBeInvisible ) { disableButton ( buttonAnimator , leftButton ) ; } else { enableButton ( buttonAnimator , leftButton ) ; } } }
enables or disables the left button , so that it matches the current member variables .
