How to convert number to words in java

Question

We currently have a crude mechanism to convert numbers to words (e.g. using a few static arrays) and based on the size of the number translating that into an english text. B

Answer 1

public class NumberConverter {

    private String[] singleDigit = {"", " one", " two", " three",
    " four", " five"," six", " seven", " eight", " nine"};

    private String[] tens = {" ten", " eleven", " twelve", " thirteen",
            " fourteen", " fifteen"," sixteen", " seventeen", " eighteen", " nineteen"};

    private String[] twoDigits = {"", "", " twenty", " thirty",
            " forty", " fifty"," sixty", " seventy", " eighty", " ninety"};

    public String convertToWords(String input) {
        long number = Long.parseLong(input);
        int size = input.length();
        if (size <= 3) {
            int num = (int) number;
            return handle3Digits(num);
        } else if (size > 3 && size <= 6) {
            int thousand = (int)(number/1000);
            int hundred = (int) (number % 1000);
            String thousands = handle3Digits(thousand);

            String hundreds = handle3Digits(hundred);
            String word = "";

            if (!thousands.isEmpty()) {
                word = thousands +" thousand";
            }
            word += hundreds;
            return word;
        } else if (size > 6 && size <= 9) {
            int million = (int) (number/ 1000000);
            number = number % 1000000;
            int thousand = (int)(number/1000);
            int hundred = (int) (number % 1000);

            String millions = handle3Digits(million);
            String thousands = handle3Digits(thousand);
            String hundreds = handle3Digits(hundred);

            String word = "";

            if (!millions.isEmpty()) {
                word = millions +" million";
            }
            if (!thousands.isEmpty()) {
                word += thousands +" thousand";
            }
            word += hundreds;
            return word;
        }

        return "Not implemented yet.";
    }


    private String handle3Digits(int number) {
        if (number <= 0)
            return "";

        String word = "";
        if (number/100 > 0) {
            int dividend = number/100;
            word = singleDigit[dividend] + " hundred";
            number = number % 100;
        }
        if (number/10 > 1) {
            int dividend = number/10;
            number = number % 10;
            word += twoDigits[dividend];
        } else if (number/10 == 1) {
            number = number % 10;
            word += tens[number];
            return word;
        } else {
            number = number % 10;
        }
        if (number > 0) {
            word += singleDigit[number];
        }

        return word;
    }
}

Answer 2

I think that this solution is not the best, since it works only for int, but i think it's great for a beginner.

public class NumberWordConverter {
    public static final String[] units = {
            "", "one", "two", "three", "four", "five", "six", "seven",
            "eight", "nine", "ten", "eleven", "twelve", "thirteen", "fourteen",
            "fifteen", "sixteen", "seventeen", "eighteen", "nineteen"
    };

    public static final String[] tens = {
            "",        // 0
            "",        // 1
            "twenty",  // 2
            "thirty",  // 3
            "forty",   // 4
            "fifty",   // 5
            "sixty",   // 6
            "seventy", // 7
            "eighty",  // 8
            "ninety"   // 9
    };

    public static String convert(final int n) {
        if (n < 0) {
            return "minus " + convert(-n);
        }

        if (n < 20) {
            return units[n];
        }

        if (n < 100) {
            return tens[n / 10] + ((n % 10 != 0) ? " " : "") + units[n % 10];
        }

        if (n < 1000) {
            return units[n / 100] + " hundred" + ((n % 100 != 0) ? " " : "") + convert(n % 100);
        }

        if (n < 1000000) {
            return convert(n / 1000) + " thousand" + ((n % 1000 != 0) ? " " : "") + convert(n % 1000);
        }

        if (n < 1000000000) {
            return convert(n / 1000000) + " million" + ((n % 1000000 != 0) ? " " : "") + convert(n % 1000000);
        }

        return convert(n / 1000000000) + " billion"  + ((n % 1000000000 != 0) ? " " : "") + convert(n % 1000000000);
    }

    public static void main(final String[] args) {
        final Random generator = new Random();

        int n;
        for (int i = 0; i < 20; i++) {
            n = generator.nextInt(Integer.MAX_VALUE);

            System.out.printf("%10d = '%s'%n", n, convert(n));
        }

        n = 1000;
        System.out.printf("%10d = '%s'%n", n, convert(n));

        n = 2000;
        System.out.printf("%10d = '%s'%n", n, convert(n));

        n = 10000;
        System.out.printf("%10d = '%s'%n", n, convert(n));

        n = 11000;
        System.out.printf("%10d = '%s'%n", n, convert(n));

        n = 999999999;
        System.out.printf("%10d = '%s'%n", n, convert(n));

        n = Integer.MAX_VALUE;
        System.out.printf("%10d = '%s'%n", n, convert(n));
    }
}

The test creates 20 random numbers up to Integer.MAX_VALUE and than some that know to be problematic, because of 0, 10, etc.. Output:

   5599908 = 'five million five hundred ninety nine thousand nine hundred eight'
 192603486 = 'one hundred ninety two million six hundred three thousand four hundred eighty six'
1392431868 = 'one billion three hundred ninety two million four hundred thirty one thousand eight hundred sixty eight'
1023787010 = 'one billion twenty three million seven hundred eighty seven thousand ten'
1364396236 = 'one billion three hundred sixty four million three hundred ninety six thousand two hundred thirty six'
1511255671 = 'one billion five hundred eleven million two hundred fifty five thousand six hundred seventy one'
 225955221 = 'two hundred twenty five million nine hundred fifty five thousand two hundred twenty one'
1890141052 = 'one billion eight hundred ninety million one hundred forty one thousand fifty two'
 261839422 = 'two hundred sixty one million eight hundred thirty nine thousand four hundred twenty two'
 728428650 = 'seven hundred twenty eight million four hundred twenty eight thousand six hundred fifty'
 860607319 = 'eight hundred sixty million six hundred seven thousand three hundred nineteen'
 719753587 = 'seven hundred nineteen million seven hundred fifty three thousand five hundred eighty seven'
2063829124 = 'two billion sixty three million eight hundred twenty nine thousand one hundred twenty four'
1081010996 = 'one billion eighty one million ten thousand nine hundred ninety six'
 999215799 = 'nine hundred ninety nine million two hundred fifteen thousand seven hundred ninety nine'
2105226236 = 'two billion one hundred five million two hundred twenty six thousand two hundred thirty six'
1431882940 = 'one billion four hundred thirty one million eight hundred eighty two thousand nine hundred forty'
1991707241 = 'one billion nine hundred ninety one million seven hundred seven thousand two hundred forty one'
1088301563 = 'one billion eighty eight million three hundred one thousand five hundred sixty three'
 964601609 = 'nine hundred sixty four million six hundred one thousand six hundred nine'
      1000 = 'one thousand'
      2000 = 'two thousand'
     10000 = 'ten thousand'
     11000 = 'eleven thousand'
 999999999 = 'nine hundred ninety nine million nine hundred ninety nine thousand nine hundred ninety nine'
2147483647 = 'two billion one hundred forty seven million four hundred eighty three thousand six hundred forty seven'

Hope it helps :)

Answer 3

Here is the code, I don't think there is any method in SE.

It basically converts number to string and parses String and associates it with the weight

for example

1000

1 is treated as thousand position and 1 gets mapped to "one" and thousand because of position

This is the code from the website:

English

import java.text.DecimalFormat;

public class EnglishNumberToWords {

  private static final String[] tensNames = {
    "",
    " ten",
    " twenty",
    " thirty",
    " forty",
    " fifty",
    " sixty",
    " seventy",
    " eighty",
    " ninety"
  };

  private static final String[] numNames = {
    "",
    " one",
    " two",
    " three",
    " four",
    " five",
    " six",
    " seven",
    " eight",
    " nine",
    " ten",
    " eleven",
    " twelve",
    " thirteen",
    " fourteen",
    " fifteen",
    " sixteen",
    " seventeen",
    " eighteen",
    " nineteen"
  };

  private EnglishNumberToWords() {}

  private static String convertLessThanOneThousand(int number) {
    String soFar;

    if (number % 100 < 20){
      soFar = numNames[number % 100];
      number /= 100;
    }
    else {
      soFar = numNames[number % 10];
      number /= 10;

      soFar = tensNames[number % 10] + soFar;
      number /= 10;
    }
    if (number == 0) return soFar;
    return numNames[number] + " hundred" + soFar;
  }


  public static String convert(long number) {
    // 0 to 999 999 999 999
    if (number == 0) { return "zero"; }

    String snumber = Long.toString(number);

    // pad with "0"
    String mask = "000000000000";
    DecimalFormat df = new DecimalFormat(mask);
    snumber = df.format(number);

    // XXXnnnnnnnnn
    int billions = Integer.parseInt(snumber.substring(0,3));
    // nnnXXXnnnnnn
    int millions  = Integer.parseInt(snumber.substring(3,6));
    // nnnnnnXXXnnn
    int hundredThousands = Integer.parseInt(snumber.substring(6,9));
    // nnnnnnnnnXXX
    int thousands = Integer.parseInt(snumber.substring(9,12));

    String tradBillions;
    switch (billions) {
    case 0:
      tradBillions = "";
      break;
    case 1 :
      tradBillions = convertLessThanOneThousand(billions)
      + " billion ";
      break;
    default :
      tradBillions = convertLessThanOneThousand(billions)
      + " billion ";
    }
    String result =  tradBillions;

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

    String tradHundredThousands;
    switch (hundredThousands) {
    case 0:
      tradHundredThousands = "";
      break;
    case 1 :
      tradHundredThousands = "one thousand ";
      break;
    default :
      tradHundredThousands = convertLessThanOneThousand(hundredThousands)
         + " thousand ";
    }
    result =  result + tradHundredThousands;

    String tradThousand;
    tradThousand = convertLessThanOneThousand(thousands);
    result =  result + tradThousand;

    // remove extra spaces!
    return result.replaceAll("^\\s+", "").replaceAll("\\b\\s{2,}\\b", " ");
  }

  /**
   * testing
   * @param args
   */
  public static void main(String[] args) {
    System.out.println("*** " + EnglishNumberToWords.convert(0));
    System.out.println("*** " + EnglishNumberToWords.convert(1));
    System.out.println("*** " + EnglishNumberToWords.convert(16));
    System.out.println("*** " + EnglishNumberToWords.convert(100));
    System.out.println("*** " + EnglishNumberToWords.convert(118));
    System.out.println("*** " + EnglishNumberToWords.convert(200));
    System.out.println("*** " + EnglishNumberToWords.convert(219));
    System.out.println("*** " + EnglishNumberToWords.convert(800));
    System.out.println("*** " + EnglishNumberToWords.convert(801));
    System.out.println("*** " + EnglishNumberToWords.convert(1316));
    System.out.println("*** " + EnglishNumberToWords.convert(1000000));
    System.out.println("*** " + EnglishNumberToWords.convert(2000000));
    System.out.println("*** " + EnglishNumberToWords.convert(3000200));
    System.out.println("*** " + EnglishNumberToWords.convert(700000));
    System.out.println("*** " + EnglishNumberToWords.convert(9000000));
    System.out.println("*** " + EnglishNumberToWords.convert(9001000));
    System.out.println("*** " + EnglishNumberToWords.convert(123456789));
    System.out.println("*** " + EnglishNumberToWords.convert(2147483647));
    System.out.println("*** " + EnglishNumberToWords.convert(3000000010L));

    /*
     *** zero
     *** one
     *** sixteen
     *** one hundred
     *** one hundred eighteen
     *** two hundred
     *** two hundred nineteen
     *** eight hundred
     *** eight hundred one
     *** one thousand three hundred sixteen
     *** one million
     *** two millions
     *** three millions two hundred
     *** seven hundred thousand
     *** nine millions
     *** nine millions one thousand
     *** one hundred twenty three millions four hundred
     **      fifty six thousand seven hundred eighty nine
     *** two billion one hundred forty seven millions
     **      four hundred eighty three thousand six hundred forty seven
     *** three billion ten
     **/
  }
}

Français Quite different than the english version but french is a lot more difficult!

package com.rgagnon.howto;

import java.text.*;

class FrenchNumberToWords {
  private static final String[] dizaineNames = {
    "",
    "",
    "vingt",
    "trente",
    "quarante",
    "cinquante",
    "soixante",
    "soixante",
    "quatre-vingt",
    "quatre-vingt"
  };

  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 FrenchNumberToWords() {}

  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:
    }

    // séparateur "-" "et"  ""
    String laLiaison = "";
    if (laDizaine > 1) {
      laLiaison = "-";
    }
    // cas particuliers
    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) {
    // 0 à 999 999 999 999
    if (number == 0) { return "zéro"; }

    String snumber = Long.toString(number);

    // pad des "0"
    String mask = "000000000000";
    DecimalFormat df = new DecimalFormat(mask);
    snumber = df.format(number);

    // XXXnnnnnnnnn
    int lesMilliards = Integer.parseInt(snumber.substring(0,3));
    // nnnXXXnnnnnn
    int lesMillions  = Integer.parseInt(snumber.substring(3,6));
    // nnnnnnXXXnnn
    int lesCentMille = Integer.parseInt(snumber.substring(6,9));
    // nnnnnnnnnXXX
    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("*** " + FrenchNumberToWords.convert(0));
    System.out.println("*** " + FrenchNumberToWords.convert(9));
    System.out.println("*** " + FrenchNumberToWords.convert(19));
    System.out.println("*** " + FrenchNumberToWords.convert(21));
    System.out.println("*** " + FrenchNumberToWords.convert(28));
    System.out.println("*** " + FrenchNumberToWords.convert(71));
    System.out.println("*** " + FrenchNumberToWords.convert(72));
    System.out.println("*** " + FrenchNumberToWords.convert(80));
    System.out.println("*** " + FrenchNumberToWords.convert(81));
    System.out.println("*** " + FrenchNumberToWords.convert(89));
    System.out.println("*** " + FrenchNumberToWords.convert(90));
    System.out.println("*** " + FrenchNumberToWords.convert(91));
    System.out.println("*** " + FrenchNumberToWords.convert(97));
    System.out.println("*** " + FrenchNumberToWords.convert(100));
    System.out.println("*** " + FrenchNumberToWords.convert(101));
    System.out.println("*** " + FrenchNumberToWords.convert(110));
    System.out.println("*** " + FrenchNumberToWords.convert(120));
    System.out.println("*** " + FrenchNumberToWords.convert(200));
    System.out.println("*** " + FrenchNumberToWords.convert(201));
    System.out.println("*** " + FrenchNumberToWords.convert(232));
    System.out.println("*** " + FrenchNumberToWords.convert(999));
    System.out.println("*** " + FrenchNumberToWords.convert(1000));
    System.out.println("*** " + FrenchNumberToWords.convert(1001));
    System.out.println("*** " + FrenchNumberToWords.convert(10000));
    System.out.println("*** " + FrenchNumberToWords.convert(10001));
    System.out.println("*** " + FrenchNumberToWords.convert(100000));
    System.out.println("*** " + FrenchNumberToWords.convert(2000000));
    System.out.println("*** " + FrenchNumberToWords.convert(3000000000L));
    System.out.println("*** " + FrenchNumberToWords.convert(2147483647));
    /*
     *** OUTPUT
     *** zéro
     *** neuf
     *** dix-neuf
     *** vingt et un
     *** vingt-huit
     *** soixante et onze
     *** soixante-douze
     *** quatre-vingt
     *** quatre-vingt-un
     *** quatre-vingt-neuf
     *** quatre-vingt-dix
     *** quatre-vingt-onze
     *** quatre-vingt-dix-sept
     *** cent
     *** cent un
     *** cent dix
     *** cent vingt
     *** deux cents
     *** deux cent un
     *** deux cent trente-deux
     *** neuf cent quatre-vingt-dix-neuf
     *** mille
     *** mille un
     *** dix mille
     *** dix mille un
     *** cent mille
     *** deux millions
     *** trois milliards
     *** deux milliards cent quarante-sept millions
     **          quatre cent quatre-vingt-trois mille six cent quarante-sept
     */
  }
}

You can handle "dollar and cent" conversion by calling the "convert" method two times.

String phrase = "12345.67" ;
Float num = new Float( phrase ) ;
int dollars = (int)Math.floor( num ) ;
int cent = (int)Math.floor( ( num - dollars ) * 100.0f ) ;

String s = "$ " + EnglishNumberToWords.convert( dollars ) + " and "
           + EnglishNumberToWords.convert( cent ) + " cents" ;

Another way to use a built-in function of your DBMS (if available). For Oracle

SQL> select to_char(to_date(873,'J'), 'JSP') as converted_form from dual;

CONVERTED_FORM
---------------------------
EIGHT HUNDRED SEVENTY-THREE

SQL>
'JSP' means :
J : the Julian format.
SP : spells the word for the number passed to to_date

Answer 4

ICU4J contains nice number-spellout support. The files with the "rules" can be easily edited, and it's no problem to add other languages (we did it e.g. for Polish and Russian).

Answer 5

package it.tommasoresti.facebook;

class NumbersToWords {

    private static final String ZERO = "zero";
    private static String[] oneToNine = {
            "one", "two", "three", "four", "five", "six", "seven", "height", "nine"
    };

    private static String[] tenToNinteen = {
            "ten", "eleven", "twelve", "thirteen", "fourteen", "fifteen", "sixteen", "seventeen", "eighteen", "nineteen"
    };

    private static String[] dozens = {
            "ten", "twenty", "thirty", "forty", "fifty", "sixty", "seventy", "eighty", "ninety"
    };

    public static String solution(int number) {
        if(number == 0)
            return ZERO;

        return generate(number).trim();
    }

    public static String generate(int number) {
        if(number >= 1000000000) {
            return generate(number / 1000000000) + " billion " + generate(number % 1000000000);
        }
        else if(number >= 1000000) {
            return generate(number / 1000000) + " million " + generate(number % 1000000);
        }
        else if(number >= 1000) {
            return generate(number / 1000) + " thousand " + generate(number % 1000);
        }
        else if(number >= 100) {
            return generate(number / 100) + " hundred " + generate(number % 100);
        }

        return generate1To99(number);
    }

    private static String generate1To99(int number) {
        if (number == 0)
            return "";

        if (number <= 9)
            return oneToNine[number - 1];
        else if (number <= 19)
            return tenToNinteen[number % 10];
        else {
            return dozens[number / 10 - 1] + " " + generate1To99(number % 10);
        }
    }
}

Test

@Test
public void given_a_complex_number() throws Exception {
    assertThat(solution(1234567890),
        is("one billion two hundred thirty four million five hundred sixty seven thousand height hundred ninety"));
}

Answer 6

You probably don't need this any more, but I recently wrote a java class to do this. Apparently Yanick Rochon did something similar. It will convert numbers up to 999 Novemdecillion (999*10^60). It could do more if I knew what came after Novemdecillion, but I would be willing to bet it's unnecessary. Just feed the number as a string in cents. The output is also grammatically correct.

Here is a link to the Bitbucket Repo