Produce random alphanumeric characters: dukes available

Question

Time for another duke giveaway
On Saturday 6th March, approx 8.00PM (GMT) the following program will be run;-
CodeMaker.javapublic class CodeMaker{
   public static void main(String []params){
      StringBuffer  sb = new StringBuffer();
      java.util.Random r = new java.util.Random();
      for(char c='A'; c<='Z'; c++) sb.append(c);
      for(char c='a'; c<='z'; c++) sb.append(c);
      for(int i=0; i<=10; i++) sb.append(i);
      for(int i=0; i<8; i++) System.out.print(sb.charAt(r.nextInt(sb.length()) ) );
ALL ARE WELCOME TO GUESS THE OUTCOME OF THIS PROGRAM AND EARN FREE DUKES!
- simply add to this thread with your guess of the 8 alphanumeric characters.
- the more characters you guess right the more you earn.
- only one guess permitted per contestant (schizoids such as the Scarlet Pimpernel excl.)
- any other rules may or may not be made by me at any time (after all it is my game so ner-ner-nee-ner-ner)
- that's all I can think of for the moment, good luck t'y'all.
The points system awarded will be determined by the following program;-
CodeScorer.javapublic class CodeScorer{
   public static void main(String []params){
      String luckyDukeWinner = params[0];
      String codeToCrack = params[1];
      String luckyDukeWinnerGuess = params[2];
      new CodeScorer(luckyDukeWinner, codeToCrack, luckyDukeWinnerGuess);
   private CodeScorer(String name, String code, String guess){
      int same = calcSame(code, guess, 0);
      int correct = calcCorrect(code, guess, 0);
      System.out.println("Number of letters correct = "+same);
      System.out.println("Number of letters exactly correct = "+correct);
      System.out.println("Dukes earned by "+name+": "+calcScore(same, correct));
   private int calcCorrect(String code, String guess, int tally){
      for (int i=0; i< code.length(); i++)
         if(guess.charAt(i) == code.charAt(i)) tally++;
      return tally;
   private int calcSame(String code, String guess, int tally){
      StringBuffer buf = new StringBuffer(code);
      for (int i=0; i< buf.length(); i++){
         for (int j=0; j< buf.length(); j++)
            if (guess.charAt(i) == buf.charAt(j)){
               tally++;
               buf.replace(j, j+1,"~");
      return tally;
   private int calcScore(int same, int correct){
      return (same>1 && correct>1)? (int)((correct*4)*(Math.pow(same,2))):(int)((correct*4)+(Math.pow(same,2)));
}

Answer 1

I thought this
for(int i=0; i<=10; i++) sb.append(i);
would do this
for(int i=0; i<=10; i++) sb.append((char)i);
I'm so humilitated....All punters may assume henceforth that line 7 char 22 is herewith removed (I'm humiliated too)