Java Algorithms Convert number to French words

import java.text.DecimalFormat;

public class Main {
   private static final String[] dizaineNames = { "", //
         "", //
         "vingt", //
         "trente", //
         "quarante", //
         "cinquante", //
         "soixante", //
         "soixante", //
         "quatre-vingt", //
         "quatre-vingt" //
   };//from w  w w.  j  a  va  2  s  .  c  o  m

   private static final String[] uniteNames1 = { "", //
         "un", //
         "deux", //
         "trois", //
         "quatre", //
         "cinq", //
         "six", //
         "sept", //
         "huit", //
         "neuf", //
         "dix", //
         "onze", //
         "douze", //
         "treize", //
         "quatorze", //
         "quinze", //
         "seize", //
         "dix-sept", //
         "dix-huit", //
         "dix-neuf" //
   };

   private static final String[] uniteNames2 = { "", //
         "", //
         "deux", //
         "trois", //
         "quatre", //
         "cinq", //
         "six", //
         "sept", //
         "huit", //
         "neuf", //
         "dix" //
   };

   private Main() {
   }

   private static String convertZeroToHundred(int number) {

      int laDizaine = number / 10;
      int lUnite = number % 10;
      String resultat = "";

      switch (laDizaine) {
      case 1:
      case 7:
      case 9:
         lUnite = lUnite + 10;
         break;
      default:
      }

      String laLiaison = "";
      if (laDizaine > 1) {
         laLiaison = "-";
      }
      switch (lUnite) {
      case 0:
         laLiaison = "";
         break;
      case 1:
         if (laDizaine == 8) {
            laLiaison = "-";
         } else {
            laLiaison = " et ";
         }
         break;
      case 11:
         if (laDizaine == 7) {
            laLiaison = " et ";
         }
         break;
      default:
      }

      // dizaines en lettres
      switch (laDizaine) {
      case 0:
         resultat = uniteNames1[lUnite];
         break;
      case 8:
         if (lUnite == 0) {
            resultat = dizaineNames[laDizaine];
         } else {
            resultat = dizaineNames[laDizaine] + laLiaison + uniteNames1[lUnite];
         }
         break;
      default:
         resultat = dizaineNames[laDizaine] + laLiaison + uniteNames1[lUnite];
      }
      return resultat;
   }

   private static String convertLessThanOneThousand(int number) {

      int lesCentaines = number / 100;
      int leReste = number % 100;
      String sReste = convertZeroToHundred(leReste);

      String resultat;
      switch (lesCentaines) {
      case 0:
         resultat = sReste;
         break;
      case 1:
         if (leReste > 0) {
            resultat = "cent " + sReste;
         } else {
            resultat = "cent";
         }
         break;
      default:
         if (leReste > 0) {
            resultat = uniteNames2[lesCentaines] + " cent " + sReste;
         } else {
            resultat = uniteNames2[lesCentaines] + " cents";
         }
      }
      return resultat;
   }

   public static String convert(long number) {
      if (number == 0) {
         return "zero";
      }

      String snumber = Long.toString(number);
      String mask = "000000000000";
      DecimalFormat df = new DecimalFormat(mask);
      snumber = df.format(number);

      int lesMilliards = Integer.parseInt(snumber.substring(0, 3));
      int lesMillions = Integer.parseInt(snumber.substring(3, 6));
      int lesCentMille = Integer.parseInt(snumber.substring(6, 9));
      int lesMille = Integer.parseInt(snumber.substring(9, 12));

      String tradMilliards;
      switch (lesMilliards) {
      case 0:
         tradMilliards = "";
         break;
      case 1:
         tradMilliards = convertLessThanOneThousand(lesMilliards) + " milliard ";
         break;
      default:
         tradMilliards = convertLessThanOneThousand(lesMilliards) + " milliards ";
      }
      String resultat = tradMilliards;

      String tradMillions;
      switch (lesMillions) {
      case 0:
         tradMillions = "";
         break;
      case 1:
         tradMillions = convertLessThanOneThousand(lesMillions) + " million ";
         break;
      default:
         tradMillions = convertLessThanOneThousand(lesMillions) + " millions ";
      }
      resultat = resultat + tradMillions;

      String tradCentMille;
      switch (lesCentMille) {
      case 0:
         tradCentMille = "";
         break;
      case 1:
         tradCentMille = "mille ";
         break;
      default:
         tradCentMille = convertLessThanOneThousand(lesCentMille) + " mille ";
      }
      resultat = resultat + tradCentMille;

      String tradMille;
      tradMille = convertLessThanOneThousand(lesMille);
      resultat = resultat + tradMille;

      return resultat;
   }

   public static void main(String[] args) {
      System.out.println(convert(0));
      System.out.println(convert(9));
      System.out.println(convert(19));
      System.out.println(convert(21));
      System.out.println(convert(97));
      System.out.println(convert(100));
      System.out.println(convert(101));
      System.out.println(convert(201));
      System.out.println(convert(232));
      System.out.println(convert(999));
      System.out.println(convert(1000));
      System.out.println(convert(10001));
      System.out.println(convert(100000));
      System.out.println(convert(2000000));
      System.out.println(convert(3000000000L));
      System.out.println(convert(2147483647));
   }
}