Please help me correct this code

Question

Hi, I have to develop a Java applications that converts a positive number from base 10 to another base. It has to prompt the user to enter the number to be converted an the base to be converted into. After conversion is completed, the program should ask for another conversion. The program would run in a loop until the user would decide to end it. In case of an error entry as a base less than 2, the program should warn the user about the type of error and ask the user to re-enter the values. At the nd of the program, provide a statistic with how many conversions the user has done.
Please look at code below, and see where i went wrong, i can't seem to figure out the formula for conversions.
import java.io.*;
public class Class1
     public static void main (String[] args)throws IOException
          int num=0;
          int base=0;
          int result;
          int rem;
          int arr[]=new int[20];
          int count=0;
          boolean prompt= true;
          for(int i=0; i<arr.length; i++)
                         while(prompt)
          //int i=0     ;
          String s;
          int x;
          BufferedReader aa =
                         new BufferedReader(new InputStreamReader(System.in));
          System.out.println("Enter a positive number for the conversion:");
          s = aa.readLine();
          num = Integer.parseInt(s);
               System.out.println("Enter the base number that you want to convert your number:");
               s=aa.readLine();
               base = Integer.parseInt(s);
               if(base >= 2)
                    if(num > 0)
                    {   rem= num%base;
                         num=num/base;
                         arr=rem;
                         System.out.println("The converted number is: " + arr[i]);
                         System.out.print("Would you like to go on (yes/no)?");
                         s=aa.readLine();
                         prompt= s.equalsIgnoreCase("no");
                         count++;
                         //i++;     
                    else
                         System.out.println("The number must be greater that 0, please enter an other number!!");
               else
                    System.out.println("The base number is not the appropriate,must be greater of two!!");
               //promt the user if he/she wants to continiue or not
               System.out.println("You have used the conversion thingy " count " times, You Freak!");
               System.in.read();

Answer 1

Since I have already started this I will try to make the conversion work. ( usually I do not like to to other people's homework ).
import java.io.*;
public class Class1
     static char[] theDigits = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
     public static void main (String[] args)throws IOException
          int num=0;
          int base=0;
          int result;
          int rem;
          String arr[]=new String[20];
          int count=0;
          boolean prompt= true;
          for(int i=0; i<arr.length && prompt; i++)     {
               while(prompt) {
                    String s;
                    int x;
                    BufferedReader aa =
                    new BufferedReader(new InputStreamReader(System.in));
                    System.out.println("Enter a positive number for the conversion:");
                    s = aa.readLine();
                    num = Integer.parseInt(s);
                    System.out.println("Enter the base number that you want to convert your number:");
                    s=aa.readLine();
                    base = Integer.parseInt(s);
                    if( base >= 2 && base < 17 ) {
                         if (num > 0)     {
                              s = "";
                              while ( num > 0 ) {
                                   rem= num%base;
                                   s = theDigits[rem] + s;
                                   num=num/base;
                              arr[count] = new String(s);
                              count++;
                              //promt the user if he/she wants to continiue or not
                              System.out.println("The converted number is: " + s + " base " + base );
                              System.out.print("Would you like to go on (yes/no)?");
                              s=aa.readLine();
                              prompt= s.equalsIgnoreCase("yes");
                         else
                              System.out.println("The number must be greater that 0, please enter an other number!!");
                    else
                         System.out.println("The base number is not the appropriate,must be greater of two and lower of 17!!");
          System.out.println("You have used the conversion thingy " +count +" times, You Freak!");
          System.in.read();
}kurt