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 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
    **/
 }
}