code: public static String encodeString(String uri)
    {
      CharBuffer cb = CharBuffer.allocate();
  
      for (int i = 0; i < uri.length(); i++) {
        char ch = uri.charAt(i);
  
        switch (ch) {
        case '<':
          cb.append("&lt;");
          break;
        case '>':
          cb.append("&gt;");
          break;
        case '&':
          cb.append("&amp;");
          break;
        default:
          cb.append(ch);
        }
      }
  
      return cb.close();
    }
docs: Escape special characters.