Exception: "org.codehaus.jackson.map.JsonMappingException: Can not deserialize instance of java.lang.String out of START_OBJECT token"

I am trying to validate a simple JSON body using Jackson, where I am storing the JSON request as a String in "dataJson" variable.

public void unmarshal(InputStream is) throws Exception { // this will contain my actual json string String dataJson= StUtil.toString(is); System.out.println(dataJson); //parse json string String response = objectMapper.readValue(dataJson, String.class); System.out.println(response); } 

SUtil.toString(InputStream is) method:

 public static String toString(final InputStream is) { final BufferedReader br = new BufferedReader(new InputStreamReader(is)); final StringBuffer buffer = new StringBuffer(); try { for (String line; (line = br.readLine()) != null; ) { buffer.append(line); } } catch (IOException ioe) { } return buffer.toString(); } 

I am learning the validation part using Jackson but it throws error/exception on line

String response = objectMapper.readValue(dataJson, String.class); 

And below is the exception I am getting -

Exception: "org.codehaus.jackson.map.JsonMappingException: Can not deserialize instance of java.lang.String out of START_OBJECT token" 

I wanted to learn what wrong am I doing. Any help on this would be appreciated.

JSON Request:

{"username" : "my_username","password" : "my_password","validation-factors":{"validationFactors":[{"name":"remote_address","value":"127.0.0.1"}]}}