Working Code.

import java.io.*;
import java.util.*;

public class Lab09
{
   public static void main(String[] args) throws FileNotFoundException
   {
      String strInput = "", strOut = "", number = "";
      int length;
      char ch;

      File myFile = new File("input.txt");
      Scanner inputFile = new Scanner(myFile);

      while (inputFile.hasNext()) {
         strInput = inputFile.nextLine();
         length = strInput.length();
         for (int i = 0; i < length; i++) {
            ch = strInput.charAt(i);
            if (Character.isUpperCase(ch)) {
               ch = Character.toLowerCase(ch);
            }
            else if (Character.isLowerCase(ch)) {
               ch = Character.toUpperCase(ch);
            }
            else if (ch >= '0' && ch <= '9') {
               switch (ch) {
                  case '0':
                     number = "zero";
                     break;
                  case '1':
                     number = "one";
                     break;
                  case '2':
                     number = "two";
                     break;
                  case '3':
                     number = "three";
                     break;
                  case '4':
                     number = "four";
                     break;
                  case '5':
                     number = "five";
                     break;
                  case '6':
                     number = "six";
                     break;
                  case '7':
                     number = "seven";
                     break;
                  case '8':
                     number = "eight";
                     break;
                  case '9':
                     number = "nine";
                     break;
               }
               if (i <= length) {
                  strOut += number;
                  if (i < strInput.length()-1 && strInput.charAt(i+1) >= '0' && strInput.charAt(i+1) <= '9') {
                     strOut += "-";
                  }
               }
            }
            if (ch < '0' || ch > '9')
               strOut += ch;
         }
      System.out.println(strOut);
      strOut = "";
      }
      inputFile.close();
   }
}