Quiero analizar un archivo JSON a través de Java utilizando Api GSON para obtener los últimos campos del archivo JSON:

descriptor.json:

{
    "Teleservice_1" : {
        "Record_1" : {
            "method_name" : "mehdi",
            "method_params": ["param1",2,"param3"]
        },
        "Record_2" : {
            "method_name" : "mkyong",
            "method_params": [3,"param2"]
        },
        "Record_3" : {
            "method_name" : "amine",
            "method_params": [3,"param1","param2"]
        }
    },
    "Teleservice_2" : {
        "Record_11" : {
            "method_name" : "mehdi1",
            "method_params": ["param11",22,"param33"]
        },
        "Record_22" : {
            "method_name" : "mkyong1",
            "method_params": [33,"param22"]
        },
        "Record_33" : {
            "method_name" : "amine1",
            "method_params": [33,"param11","param22"]
        }
    },
    "Teleservice_3" : {
        "Record_111" : {
            "method_name" : "mehdi2",
            "method_params": ["param111",222,"param333"]
        },
        "Record_222" : {
            "method_name" : "mkyong2",
            "method_params": [333,"param222"]
        },
        "Record_333" : {
            "method_name" : "amine2",
            "method_params": [333,"param111","param222"]
        }
    }
}

ListTeleServices.java:

import java.util.HashMap;

public class ListTeleServices {

    private HashMap<String, TeleService> listTeleServices;

    public ListTeleServices() {

    }

    public TeleService getTeleService(String teleserviceName) {
        if(this.listTeleServices.get(teleserviceName) != null) 
            return this.listTeleServices.get(teleserviceName);
        else
            return null;
    }
}

TeleService.java:

import java.util.HashMap;

public class TeleService {

    private HashMap<String, Record> listRecords;

    public TeleService() {

    }

    public Record getRecord(String recordName) {
        if(this.listRecords.get(recordName) != null) 
            return this.listRecords.get(recordName);
        else
            return null;
    }
}

Record.java:

public class Record {

    private String method_name;
    private Object[] method_parameters; 

    public Record(String methodName, Object[] methodParameters) {
        this.method_name = new String(methodName);
        this.method_parameters = methodParameters;
    }

    public String getMethodName() {
        return this.method_name;
    }

    public Object[] getMethodParameters() {
        return this.method_parameters;
    }

    public void setMethodName(String methodName) {
        this.method_name = methodName;
    }

    public void setMethodParameters(Object[] methodParameters) {
        this.method_parameters = methodParameters;
    }
}

Y finalmente mi clase de analizador,JSONMainParse.java:

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import com.google.gson.Gson;


public class JSONMainParse {

    public static void main(String[] args) throws FileNotFoundException {

        BufferedReader br = new BufferedReader(new FileReader("/Users/Mehdi/Desktop/descriptor.json"));
        Gson gson = new Gson();
        ListTeleServices teleservices = gson.fromJson(br, ListTeleServices.class);
        String methodName = teleservices.getTeleService("Teleservice_2").getRecord("Record_33").getMethodName();

        System.out.println(methodName);
    }
}

Me parece correcto, y debería mostrar: "amine1" pero me da unExcepción de puntero nulo a :

ListTeleServices.getTeleService (ListTeleServices.java:12) cual es :

if(this.listTeleServices.get(teleserviceName) != null) 

yen JSONMainParse.main (JSONMainParse.java:15) cual es :

String methodName = teleservices.getTeleService("Teleservice_2").getRecord("Record_33").getMethodName();

Tienes alguna idea sobre esto ? Gracias :)