print all number 1 to 9999 in words using java

Question

I am trying to print all number 1 to 9999 in words using java. I wrote below code

import java.util.*;
public class NubersTOWords {
    public static void main(String a[])
    {
        Scanner obj = new Scanner(System.in);
        System.out.println("Enter  number :");
        int num =obj.nextInt();
        int digit1,digit2;
        String st1[] ={ "",
                "one",
                "two",
                "three",
                "four",
                "five",
                "six",
                "seven",
                "eight",
                "nine","Ten","Eleven","Twelve","Thirteen","fourteen","Fifteen","Sixteen","Seventeen","Eighteen","Nineteen"};
        String st2[] ={"","","Twenty","Thirty","Forty","Fifty","Sixty","Seventy","Eighty","Ninety"};
        String st3[]={"Hundred","Thousand"};
    /*  
        if(num <0 || num>=100)
        {
            System.out.println("Wrong number");

        }*/
        if(num >1 && num <20 )
        {
            System.out.println(st1[num]);
        }
        else if(num >=20 && num <=99) 
        {
            digit1 =num/10;
            digit2 =num%10;
            System.out.println(st2[digit1]+" "+st1[digit2]);

        }
        else if(num >=100 && num <=9999) 
        {
            //Here how to change my code?
        }

    }

}

Above code satisfied the requirements 1-100 but how to full fill upto 9999.

How to complete the requirements from this code?

Code would be appreciable.

Answer 1

If you are using java8 then you can use this code:

public class PrintAllNumbers {

    public static void main(String[] args) {
        IntStream.rangeClosed(0, 9999)
        .mapToObj(i-> EnglishNumberToWords.convert(i))
        .forEach(System.out::println);
    }

}

in combination with this great answer https://stackoverflow.com/a/3911987/476791 :

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
     **/
  }
}