code: public static String toHexString(byte[] b) {
          StringBuilder sb = new StringBuilder(b.length * 2);
          for (byte aByte : b) {
              // look up high nibble char
              sb.append(hexChar[(aByte & 0xf0) >>> 4]);
  
              // look up low nibble char
              sb.append(hexChar[aByte & 0x0f]);
          }
          return sb.toString();
      }
docs: Convert a byte array to a hex string.
  
  @param b The byte array
  @return The hex String