public static String randomAlphanumerical(final int len){
  final StringBuilder sb=new StringBuilder(len);
  for (int i=0; i < len; i++) {
    sb.append(AB.charAt(random.nextInt(AB.length())));
  }
  return sb.toString();
}

public static String randomAlphanumerical ( final int len ) { final StringBuilder sb = new StringBuilder ( len ) ; for ( int i = 0 ; i < len ; i ++ ) { sb . append ( AB . charAt ( random . nextInt ( AB . length ( ) ) ) ) ; } return sb . toString ( ) ; }
generates a random alphanumerical string of the given length . the used characters are : < br > < br > 0123456789abcdefghijklmnopqrstuvwxyz
