RatingBinder.java

/**
 * This binder is needed to prevent a NullPointerException cases when
 * Android's Data Binding Library Binder class tries to bind the value
 * for rating when the model isn't setted yet.
 * */
public class RatingBinder {
    @BindingAdapter({"rating"})
    public static void setRating(RatingBar ratingBar, Float rating) {
        if (rating != null) {
            ratingBar.setRating(rating);
        }
    }
}