public static boolean filtersSame(@Nullable final GeocacheFilter filter1, @Nullable final GeocacheFilter filter2) {
        if (filter1 == filter2) {
            return true;
        }
        if (filter1 == null || filter2 == null) {
            return false;
        }
        return filter1.filtersSame(filter2);
    }
returns true if this filter and other filter would filter same results
main/src/main/java/cgeo/geocaching/filters/core/GeocacheFilter.java