code: public static boolean isSafeChar(char ch) {
          if (ch >= 'a' && ch <= 'z')
              return true;
          if (ch >= 'A' && ch <= 'Z')
            return true;
          if (ch >= '0' && ch <= '9')
            return true;
          // loop thru our PRINTABLE string
          for (int i = 0; i < SAFE.length(); i++) {
              if (ch == SAFE.charAt(i))
                  return true;
          }
          return false;
      }
docs: Returns true if the char is considered a "safe" char. Please see
  documentation for isSafeString().
  @see #isSafeString(java.lang.String)