code: protected static String _escapeQuotesAndBackslashes(String s) {
      final StringBuilder buf = new StringBuilder(s);
      
      // Walk backwards, looking for quotes or backslashes.
      //  If we see any, insert an extra backslash into the buffer at
      //  the same index.  (By walking backwards, the index into the buffer
      //  will remain correct as we change the buffer.)
      for (int i = s.length()-1; i >= 0; i--) {
        char c = s.charAt(i);
        if ((c == '\\') || (c == '"')) {
          buf.insert(i, '\\');
        }
        // Replace any special characters with escaped versions
        else if (c == '\n') {
          buf.deleteCharAt(i);
          buf.insert(i, "\\n");
        }
        else if (c == '\t') {
          buf.deleteCharAt(i);
          buf.insert(i, "\\t");
        }
        else if (c == '\r') {
          buf.deleteCharAt(i);
          buf.insert(i, "\\r");
        }
        else if (c == '\b') {
          buf.deleteCharAt(i);
          buf.insert(i, "\\b");
        }
        else if (c == '\f') {
          buf.deleteCharAt(i);
          buf.insert(i, "\\f");
        }
      }
      return buf.toString();
    }
docs: Inserts backslashes before any occurrences of a backslash or
  quote in the given string.  Also converts any special characters
  appropriately.