Medium Article

clicks.java

RxView.clicks(fab)
      .throttleFirst(1, TimeUnit.SECONDS) // prevents crazy clicks
      .observeOn(AndroidSchedulers.mainThread()) 
      .switchMap(ignore -> favoritesManager.addOrRemoveFromFavs(postId)) // toggle cache state and make API request
      .subscribe(responseOrError -> {
          if (responseOrError.isError()) {
              Toast.makeText(PostDetailsActivity.this, "API error", Toast.LENGTH_SHORT).show();
          }
      })

favSub.java

favsManager.getFavObservable(postId)
  .subscribe(isFavorite -> favButton.setFavorite(isFavrotie));

isFavObservable.java

favoritesManager.getIsFavoriteObservable(postId)
        .subscribe(isFavorite -> fab.setImageDrawable(getResources().getDrawable(isFavorite ?
               R.drawable.ic_favorite_black_24dp : R.drawable.ic_favorite_border_black_24dp)))

mistake1.java

void onFavoriteButtonClick() { 
   favoriteButton.setFavorite(favoriteButton.isFavrotie())
   makeFavRequest(favoriteButton.isFavrotie())
}

toogleValue.java

favoritesManager.toggleValue(postId);