Conversione di oggetti Json in oggetti Java utilizzando Google Gson

Question

Sto utilizzando Spring Social FqlQuery per ottenere dati da Facebook. Ecco la risposta JSON che sto ricevendo da facebook. Il mio controller dove sto ottenendo uscita JSON è qui,

fql = "SELECT work FROM user WHERE uid = me()"; 
facebook.fqlOperations().query(fql, new FqlResultMapper<Object>() { 
    public Object mapObject(FqlResult result) { 
     List list = (List) result.getObject("work"); 
     for (Object object : list) { 
      JsonHelper jsonHelper = new JsonHelper(); 
      Gson gson = new GsonBuilder().setPrettyPrinting().create(); 
      String jsonOutput = gson.toJson(object); 
      System.out.println(jsonOutput); 
      gson.fromJson(jsonOutput, JsonHelper.class); 
     } 

System.out.println all'interno per ciclo restituisce JSON multipla, come di seguito .:

{ 
    "employer": { 
    "id": 129843057436, 
    "name": "www.metroplots.com" 
    }, 
    "location": { 
    "id": 102186159822587, 
    "name": "Chennai, Tamil Nadu" 
    }, 
    "position": { 
    "id": 108480125843293, 
    "name": "Web Developer" 
    }, 
    "start_date": "2012-10-01", 
    "end_date": "2013-05-31" 
} 
{ 
    "employer": { 
    "id": 520808381292985, 
    "name": "Federation of Indian Blood Donor Organizations" 
    }, 
    "start_date": "0000-00", 
    "end_date": "0000-00" 
} 

Ecco la mia classe helper:

import java.util.List; 

public class JsonHelper { 

class Employer{ 
    private int id; 
    private String name; 
    public int getId() { 
     return id; 
    } 
    public void setId(int id) { 
     this.id = id; 
    } 
    public String getName() { 
     return name; 
    } 
    public void setName(String name) { 
     this.name = name; 
    } 

} 
class Location{ 
    private int id; 
    private String name; 
    public int getId() { 
     return id; 
    } 
    public void setId(int id) { 
     this.id = id; 
    } 
    public String getName() { 
     return name; 
    } 
    public void setName(String name) { 
     this.name = name; 
    } 

} 
class Position{ 
    private int id; 
    private String name; 
    public int getId() { 
     return id; 
    } 
    public void setId(int id) { 
     this.id = id; 
    } 
    public String getName() { 
     return name; 
    } 
    public void setName(String name) { 
     this.name = name; 
    } 
} 
//Edited After here 
private String start_Date; 
private String end_Date; 
private Employer employer; 
private Location location; 
private Position position; 
public String getStart_Date() { 
    return start_Date; 
} 
public void setStart_Date(String start_Date) { 
    this.start_Date = start_Date; 
} 
public String getEnd_Date() { 
    return end_Date; 
} 
public void setEnd_Date(String end_Date) { 
    this.end_Date = end_Date; 
} 
public Employer getEmployer() { 
    return employer; 
} 
public void setEmployer(Employer employer) { 
    this.employer = employer; 
} 
public Location getLocation() { 
    return location; 
} 
public void setLocation(Location location) { 
    this.location = location; 
} 
public Position getPosition() { 
    return position; 
} 
public void setPosition(Position position) { 
    this.position = position; 
} 
} 

Quando provo a convertire gli oggetti json in oggetto java come sopra ho ricevuto questa eccezione.

HTTP Status 500 - Request processing failed; nested exception is com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_ARRAY but was BEGIN_OBJECT at line 6 column 16 

Qualcuno può aiutarmi dove mi sbaglio. Per favore aiutami a convertire json in oggetti java. Spero che la mia domanda sia chiara. Grazie in anticipo.

modifica apportata al regolatore:

facebook.fqlOperations().query(fql, new FqlResultMapper<Object>() { 
public Object mapObject(FqlResult result) { 
List<JsonHelper> json = new ArrayList<JsonHelper>(); 
List list = (List) result.getObject("work"); 

for (Object object : list) { 
    Gson gson = new GsonBuilder().setPrettyPrinting().create(); 
    String jsonOutput = gson.toJson(object); 
    System.out.println(jsonOutput); 
    JsonHelper jsonHelper = gson.fromJson(jsonOutput, JsonHelper.class); 
    json.add(jsonHelper); 
    System.out.println(jsonHelper.getStart_Date()); 
} 

for (JsonHelper jsonHelper : json) { 
    System.out.println(jsonHelper.getStart_Date()); 
} 

return list; 
} 

}); 

Answer 1

poiché non sono avendo accesso effettivo api, così sto provando con valore statico nell'esempio. In primo luogo nella classe JsonHelper, sostituire tutto per long, poiché i valori citati in json sono di tipo long e String. Poi provare Come accennato qui sotto:

  String str = "{\n" 
      + " \"employer\": {\n" 
      + " \"id\": 129843057436,\n" 
      + " \"name\": \"www.metroplots.com\"\n" 
      + " },\n" 
      + " \"location\": {\n" 
      + " \"id\": 102186159822587,\n" 
      + " \"name\": \"Chennai, Tamil Nadu\"\n" 
      + " },\n" 
      + " \"position\": {\n" 
      + " \"id\": 108480125843293,\n" 
      + " \"name\": \"Web Developer\"\n" 
      + " },\n" 
      + " \"start_date\": \"2012-10-01\",\n" 
      + " \"end_date\": \"2013-05-31\"\n" 
      + "}"; 


    List<JsonHelper> json = new ArrayList<JsonHelper>(); 
    Gson gson = new Gson(); 
    JsonHelper users = gson.fromJson(str, JsonHelper.class); 
    json.add(users); 


    for (JsonHelper js_obj : json) { 
     System.out.println(js_obj.getEmployer().getId()); 
     System.out.println(js_obj.getEmployer().getName()); 
    }