Figure to words converting program in java(simplified for beginners..)

/*        
 *Before we get into it, this is strictly intended for beginners, i've organized the code in such a way that in       *which even a beginner(might be a basic understanding about java) could understand . just look at code
 *  and see what happens. I've tried to make it quite simpler with comments. so, beginners, spend some time
 *  in this  tutorial and develop it further for , say for 12 digits.
 *Originally written by :sarathantony@yahoo.co.in
 */
package figuretowords;
import java.io.*;

/**
 *
 * @author sarathantony */
public class FigureToWords {
   
   static  int i=0;
  
//for 1,2,3,etc....    also further for <twenty>one, <thirty>two, etc..
//u get the idea?, even if u don't u'll get it when u reach main method

    public  void singleDigit(int i) {
        switch(i) {
            case 1: System.out.print("one");
                break;
            case 2: System.out.print("two");
                break;
            case 3: System.out.print("three");
                break;
            case 4: System.out.print("four");
                break;
            case 5: System.out.print("five");
                break;
            case 6: System.out.print("six");
                break;
            case 7: System.out.print("seven");
                break;
            case 8: System.out.print("eight");
                break;
            case 9: System.out.print("nine");
                break;
            case 0: System.out.print("");
                break;
               
        }
    }
//for 10,20,30,etc...
          public  void twoDigit(int i) {
        switch(i) {
            case 1: System.out.print("ten");
                break;
            case 2: System.out.print("twenty");
                break;
            case 3: System.out.print("thirty");
                break;
            case 4: System.out.print("fourty");
                break;
            case 5: System.out.print("fifty");
                break;
            case 6: System.out.print("sixty");
                break;
            case 7: System.out.print("seventy");
                break;
            case 8: System.out.print("eighty");
                break;
            case 9: System.out.print("ninenty");
                break;
            case 0: System.out.print("");
                break;
        }        
    }
          public  void caseOne(int i) {
        switch(i) {
            case 1: System.out.print("eleven");
                break;
            case 2: System.out.print("twelve");
                break;
            case 3: System.out.print("thirteen");
                break;
            case 4: System.out.print("fourteen");
                break;
            case 5: System.out.print("fifteen");
                break;
            case 6: System.out.print("sixteen");
                break;
            case 7: System.out.print("seventeen");
                break;
            case 8: System.out.print("eighteen");
                break;
            case 9: System.out.print("ninenteen");
                break;
            case 0: System.out.print("");
                break;
        }        
    }
 


    public static void main(String[] args) {
       
        try {
       
        FigureToWords ac= new FigureToWords();
       
        BufferedReader br= new BufferedReader(new InputStreamReader(System.in));
            System.out.println("Enter a number:");   
       
     String number= br.readLine();
     int length= number.length();
     String[] str= number.split("");
     int[] amount= new int[length];
    
     for(i=0; i<length;i++) {
         amount[i]= Integer.parseInt(str[i+1]);
     }
   // u get that idea, why i use a flag? 
    int flag;
      
       for( i=0, flag=length ; i<length && flag>=1; ) {
          
           switch(flag) {
              
               case 9:
               
                   if(amount[i] == 1){
                       ac.caseOne(amount[i+1]);
                       System.out.print(" crore ");
                       i=i+2;
                       flag=flag-2;
                       break;
                      
                   }
                   else if(amount[i+1]==0){
                       ac.twoDigit(amount[i]);
                       System.out.print(" crore ");
                       i=i+2;
                       flag=flag-2;
                   }
                   else {
                    
                       ac.twoDigit(amount[i]);
                       ac.singleDigit(amount[i+1]);
                       i=i+2;
                       flag=flag-2;
                       System.out.print(" crore ");
                       break;
                      
                  }
                 
                  
               case 8:
                   ac.singleDigit(amount[i]);
                   System.out.print(" crore ");
                   i++;
                   flag--;
                   break;
                  
                  
                case 7:
               
                   if(amount[i] == 1){
                       ac.caseOne(amount[i]);
                       i=i+2;
                       flag=flag-2;
                       System.out.print(" lakh ");
                       break;
                      
                   }
                   else if(amount[i+1]==0){
                       ac.twoDigit(amount[i]);
                       i=i+2;
                       flag=flag-2;
                       System.out.print(" lakh ");
                       break;
                   }
                   else {
                    
                       ac.twoDigit(amount[i]);
                       ac.singleDigit(amount[i+1]);
                       i=i+2;
                       flag=flag-2;
                       System.out.print("lakh");
                       break;
                      
                  }
                 
                  
               case 6:
                   ac.singleDigit(amount[i]);
                   System.out.print(" lakh ");
                   i++;
                   flag--;
                   break;
                      
               
                case 5:
               
                   if(amount[i] == 1){
                       ac.caseOne(amount[i]);
                       System.out.print(" thousand ");
                       i=i+2;
                       flag=flag-2;
                       break;
                      
                   }
                   else if(amount[i+1]==0){
                       ac.twoDigit(amount[i]);
                       i=i+2;
                       flag=flag-2;
                       System.out.print(" thousand ");
                       break;
                   }
                   else {
                    
                       ac.twoDigit(amount[i]);
                       ac.singleDigit(amount[i+1]);
                       i=i+2;
                       flag=flag-2;
                       System.out.print(" thousand ");
                       break;
                      
                  }
                 
                  
               case 4:
                   ac.singleDigit(amount[i]);
                   i++;
                   flag--;
                   System.out.print(" thousand ");
                   break;
                      
                case 3:
                   ac.singleDigit(amount[i]);
                   i++;
                   flag--;
                  
                   System.out.print(" hunderd ");
                   break;
                   
                case 2:
                    if(amount[i] == 0) {
                       i=i+1;
                       flag=flag-1;
                        break;
                    }
                   
                    else if (amount[i]==1) {
                        ac.caseOne(amount[i+1]);
                        i=i+2;
                        flag=flag-2;
                        break;
                       
                       
                       
                    }
                    else {
                        ac.twoDigit(amount[i]);
                        ac.singleDigit(amount[i+1]);
                        i=i+2;
                        flag=flag-2;
                        break;
                       
                    }
          
                case 1:
                    ac.singleDigit(amount[i]);
                    i++;
                    flag--;
                    break;
                   
                default:
                    System.out.println("fialed");
                                      
               }//end of switch
          
       }//end of for
      
        System.out.print("only");
        System.out.println("");
  }
    catch (Exception e) {
            System.out.println("ERROR"+e);
}
        }//end of main
}//end of class
      

//well, this isn't the end, u can still expand it further or u could convert a float too..
//but remember, this is just a beginner's tutorial.
//for further, find me on  facebook.com/sarathantony