how to convert from string into json format in spring rest api
<p>this is the code:</p>

<pre><code>@RequestMapping(value="/find/city={city}", method=RequestMethod.GET)
public @ResponseBody String getCity(@PathVariable String city) throws JsonParseException, IOException
{      
  ObjectMapper mapper = new ObjectMapper();
  SimpleBeanPropertyFilter theFilter = SimpleBeanPropertyFilter.serializeAllExcept("id","miscellaneous","country","foundin","code","latlong","state");
  FilterProvider filters = new SimpleFilterProvider().addFilter("myFilter", theFilter);
  String content = "";
  StringBuilder builder = new StringBuilder();
  List&lt;Master_City&gt; list = City_Repository.findByCityLikeIgnoreCase(city);
 for (Master_City json : list)
  {
     builder.append( mapper.writer(filters).writeValueAsString(json));
    }
 content = builder.toString();
 return content;
}
</code></pre>

<p>output is not in json ,it's a string:</p>

<pre><code>{"indexid":65,"city":"Barcelona"}{"indexid":158,"city":"Dillons Bay"}     {"indexid":232,"city":"East London"}{"indexid":411,"city":"Londonderry"{"indexid":587,"city":"Thessaloniki"}{"indexid":818,"city":"Bouillon"}{"indexid":1719,"city":"Flin Flon"}{"indexid":2073,"city":"Clonmel"}
</code></pre>

<p>I need in this format:</p>

<p>[
  {
    "indexid": "425",
    "city": "Flin Flon"
  },
  {
    "indexid": "220",
    "city": "London"
  },
  {
    "indexid": "525",
    "city": "Longyear"
  }
  ]</p>