public static String toHexString(byte[] bytes){
  if (bytes == null)   return "";
  int i;
  String ret="";
  String tmp;
  for (i=0; i < bytes.length; i++) {
    if (i > 0)     ret+=":";
    tmp=Integer.toHexString(U8.f(bytes[i]));
    if (tmp.length() == 1)     ret+="0";
    ret+=tmp;
  }
  return ret;
}

public static String toHexString ( byte [ ] bytes ) { if ( bytes == null ) return "" ; int i ; String ret = "" ; String tmp ; for ( i = 0 ; i < bytes . length ; i ++ ) { if ( i > 0 ) ret += ":" ; tmp = Integer . toHexString ( U8 . f ( bytes [ i ] ) ) ; if ( tmp . length ( ) == 1 ) ret += "0" ; ret += tmp ; } return ret ; }
convert a string of bytes to a ' : ' separated hex string
