Java Random create random String example 2

import java.util.Random;

public class Main {
   public static void main(String args[]) {
      String str1 = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
      int length = 10;
      StringBuilder sb = new StringBuilder(length);
      Random r = new Random();

      for (int j = 0; j < length; j++) {
         sb.append(str1.charAt(r.nextInt(str1.length())));
      }/*from   www. j  a v a 2s .c  o  m*/
      System.out.println(sb.toString());
 
   }
}