code: private void setBestFractionRule(int originalIndex, NFRule newRule, boolean rememberRule) {
          if (rememberRule) {
              if (fractionRules == null) {
                  fractionRules = new LinkedList<NFRule>();
              }
              fractionRules.add(newRule);
          }
          NFRule bestResult = nonNumericalRules[originalIndex];
          if (bestResult == null) {
              nonNumericalRules[originalIndex] = newRule;
          }
          else {
              // We have more than one. Which one is better?
              DecimalFormatSymbols decimalFormatSymbols = owner.getDecimalFormatSymbols();
              if (decimalFormatSymbols.getDecimalSeparator() == newRule.getDecimalPoint()) {
                  nonNumericalRules[originalIndex] = newRule;
              }
              // else leave it alone
          }
      }
docs: Determine the best fraction rule to use. Rules matching the decimal point from
  DecimalFormatSymbols become the main set of rules to use.
  @param originalIndex The index into nonNumericalRules
  @param newRule The new rule to consider
  @param rememberRule Should the new rule be added to fractionRules.