public static boolean isHexCharacter(final char c) {
    return isDecCharacter(c) || ((c >= 'a') && (c <= 'f')) || ((c >= 'A') && (c <= 'F'));
  }
Tests whether a character is a valid character of a hexadecimal string.

@param c The character to test.
@return True, if the character is a hex character. False, otherwise.
java/zylib/src/main/java/com/google/security/zynamics/zylib/general/Convert.java