java - How to directly write to a JSON object (ObjectNode) from ObjectMapper in Jackson JSON? -

i'm trying output json object in jackson json. however, couldn't json object using following code.

public class myclass {          private objectnode jsonobj;          public objectnode getjson() {               objectmapper mapper = new objectmapper();               // code generate object user...               mapper.writevalue(new file("result.json"), user);               jsonobj = mapper.createobjectnode();               return jsonobj;         }  } 

after program runs, file result.json contains correct json data. however, jsonobj empty (jsonobj={}). looked javadoc of objectmapper couldn't find easy way write objectnode (json object in jackson). there no method in objectmapper following:

public void writevalue(objectnode json, object value) 

how write objectnode directly objectmapper?

you need make use of objectmapper#valuetotree() instead.

this construct equivalent json tree representation. functionally same if serializing value json , parsing json tree, more efficient.

you don't need write user object out json file, if that's not required.

public class myclass {      private objectnode jsonobj;      public objectnode getjson() {       objectmapper mapper = new objectmapper();       // code generate object user...       jsonnode jsonnode = mapper.valuetotree(user);       if (jsonnode.isobject()) {         jsonobj = (objectnode) jsonnode;         return jsonobj;       }       return null;     } }