คือว่าจากโค๊ดมันก็แปลงได้แล้วครับ แต่ติดตรงหลักพันกับหลักแสน ครับ
package Test;

import java.text.DecimalFormat;
import java.util.Scanner;

public class EnglishNumberToWords {

  private static final String[] tensNames = {
    "",
    "สิบ",
    "ยี่สิบ",
    "สามสิบ",
    "สี่สิบ",
    "ห้าสิบ",
    "หกสิบ",
    "เจ็ดสิบ",
    "แปดสิบ",
    "เก้าสิบ"
  };

  private static final String[] numNames = {
    "",
    "หนึ่ง",
    "สอง",
    "สาม",
    "สี่",
    "ห้า",
    "หก",
    "เจ็ด",
    "แปด",
    "เก้า",
    "สิบ",
    "สิบเอ็ด",
    "สิบสอง",
    "สิบสาม",
    "สิบสี่",
    "สิบห้า",
    "สิบหก",
    "สิบเจ็ด",
    "สิบแปด",
    "สิบเก้า"
  };

  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] + "ร้อย" + soFar;
  }


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

    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)
      + "พันล้าน ";
      break;
    default :
      tradBillions = convertLessThanOneThousand(billions)
      + "พันล้าน ";
    }
    String result =  tradBillions;

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

    String tradHundredThousands;
    switch (hundredThousands) {
    case 0:
      tradHundredThousands = "";
      break;
    case 1 :
      tradHundredThousands = "หนึ่งพัน ";
      break;
    default :
      tradHundredThousands = convertLessThanOneThousand(hundredThousands)
         + "พัน ";
    }
    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) {
      
      Scanner sc = new Scanner(System.in);
      System.out.print("Input The Number : ");
      int sc1 = sc.nextInt();
      System.out.println("************************");
      System.out.println("*** " + EnglishNumberToWords.convert(sc1));
      System.out.println("************************");

  }
}