code: public String escape(String in) {
      StringBuffer out = new StringBuffer();
  
      for (char c : in.toCharArray()) {
        switch (c) {
          case '<':
            out.append("&lt;");
            break;
          case '>':
            out.append("&gt;");
            break;
          case '&':
            out.append("&amp;");
            break;
          case '"':
            out.append("&quot;");
            break;
          default:
            out.append(c);
        }
      }
  
      return out.toString();
    }
docs: Translate reserved XML characters to XML entities.
  @param in Input string.