Develop Reference

FlatMapFunction with spark java

I am trying to implement transformation logic using flatmap on 7gb input json file.
following code snippet throws
Cannot resolve method 'flatMap(anonymous org.apache.spark.api.java.function.FlatMapFunction<org.apache.spark.sql.Row,com.test.mapper.ProductType>)'
any suggestions please.
dataset is a Dataset<Row> of input json file.
dataset.flatMap(new FlatMapFunction<Row, ProductType>() {
private static final long serialVersionUID = -432662341173300339L;
#Override
public Iterator<ProductType> call(Row row) throws Exception {
List<ProductType> productTypeList = new ArrayList<>();
GenericRowWithSchema dep = row.getAs("dep");
GenericRowWithSchema identity = Util.getRow(dep, "identity");
String dt= Util.getValue(dep, "startDate");
String flg = Util.getValue(dep, "withdrawalPenalty");
return productTypeList.iterator();
}
});
public class ProductType implements Serializable {
String id;
String domain;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getDomain() {
return domain;
}
public void setDomain(String domain) {
this.domain = domain;
}
}
class Util{
public static GenericRowWithSchema getRow(GenericRowWithSchema row, String fieldName) {
try {
return row.getAs(fieldName);
} catch(Exception ex) {
return null;
}
}
public static String getValue(Row row, String fieldName) {
try {
return row.getAs(fieldName);
} catch(Exception ex) {
return "";
}
}
}

Problem trying to read a json file in Java with the MVC pattern

I'm trying to print some JSONObjects from a JSONArray in JAVA using the MVC pattern and the json.simple library, but when I run it the program just print the last JSONObject.
This is my Main class:
package Main;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import org.json.simple.JSONArray;
import org.json.simple.JSONObject;
import org.json.simple.parser.JSONParser;
import org.json.simple.parser.ParseException;
import Controlador.Controlador;
import Vista.Vista;
import Modelo.Modelo;
public class Main {
private static String ID;
public static void main(String[] args) throws IOException, InterruptedException {
Modelo modelo = llenarDatosModelo();
Vista vista = new Vista();
//se crea un objeto controlador y se le pasa el modelo y la vista
Controlador controlador = new Controlador(modelo, vista);
// se muestra los datos
controlador.actualizarVista();
}
//método estático que retorna el autor con sus datos
private static Modelo llenarDatosModelo() {
JSONParser jsonParser = new JSONParser ();
try(FileReader reader = new FileReader ("datos.json")) {
JSONObject documento = (JSONObject) jsonParser.parse(reader);
JSONObject resultados = (JSONObject)documento.get("search-results");
JSONArray Entrys = (JSONArray) resultados.get("entry");
for(Object Entry: Entrys) {
mostrarInformacionEntry ((JSONObject) Entry);
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch(IOException e) {
e.printStackTrace();
} catch(ParseException e) {
e.printStackTrace();
}
Modelo autor = new Modelo();
autor.setID(ID);
return autor;
}
private static void mostrarInformacionEntry(JSONObject entry) {
ID = (String) entry.get("dc:identifier");
}
This is my model:
package Modelo;
public class Modelo {
private String ID;
private String url;
private String eid;
private String document_count;
private String cited_by_count;
private String citation_count;
private String affiliation;
private String give_name;
private String classification;
private String publication_start;
private String publication_end;
public Modelo() {
}
public String getID() {
return ID;
}
public void setID(String string) {
this.ID = string;
}
public String geturl() {
return url;
}
public void seturl(String url) {
this.url = url;
}
public String geteid() {
return eid;
}
public void seteid(String eid) {
this.eid = eid;
}
public String getdocument_count() {
return document_count;
}
public void setdocument_count(String document_count) {
this.document_count = document_count;
}
public String getcited_by_count() {
return cited_by_count;
}
public void setcited_by_count(String cited_by_count) {
this.cited_by_count = cited_by_count;
}
public String getcitation_count() {
return citation_count;
}
public void setcitation_count(String citation_count) {
this.citation_count = citation_count;
}
public String getaffiliation() {
return affiliation;
}
public void setaffiliation(String affiliation) {
this.affiliation = affiliation;
}
public String getgive_name() {
return give_name;
}
public void setgive_name(String give_name) {
this.give_name = give_name;
}
public String getclassification() {
return classification;
}
public void setclassification(String classification) {
this.classification = classification;
}
public String getpublication_start() {
return publication_start;
}
public void setpublication_start(String publication_start) {
this.publication_start = publication_start;
}
public String getpublication_end() {
return publication_end;
}
public void setpublication_end(String publication_end) {
this.publication_end = publication_end;
}
}
This is my View:
package Vista;
public class Vista {
public void imprimirDatos(String string,String url, String eid, String document_count, String cited_by_count, String citation_count, String affiliation, String give_name, String classification, String publication_start, String publication_end) {
System.out.println("\n****AUTOR****");
System.out.println("ID: "+string);
System.out.println("url: "+url);
System.out.println("eid: "+eid);
System.out.println("document_count: "+document_count);
System.out.println("cited_by_count: "+cited_by_count);
System.out.println("citation_count: "+citation_count);
System.out.println("affiliation: "+affiliation);
System.out.println("give_name: "+give_name);
System.out.println("classification: "+classification);
System.out.println("publication_start: "+publication_start);
System.out.println("publication_end: "+publication_end);
}
}
And this is my controller:
package Controlador;
import Modelo.Modelo;
import Vista.Vista;
public class Controlador {
//objetos vista y modelo
private Vista vista;
private Modelo modelo;
//constructor para inicializar el modelo y la vista
public Controlador(Modelo modelo, Vista vista) {
this.modelo = modelo;
this.vista = vista;
}
//getters y setters para el modelo
public String getID() {
return modelo.getID();
}
public void setID(String ID) {
this.modelo.setID(ID);
}
public String geturl() {
return modelo.geturl();
}
public void seturl(String url) {
this.modelo.seturl(url);
}
public String geteid() {
return modelo.geteid();
}
public void seteid(String eid) {
this.modelo.seteid(eid);
}
public String getdocument_count() {
return modelo.getdocument_count();
}
public void setdocument_count(String document_count) {
this.modelo.setdocument_count(document_count);
}
public String getcited_by_count() {
return modelo.getcited_by_count();
}
public void setcited_by_count(String cited_by_count) {
this.modelo.setcited_by_count(cited_by_count);
}
public String getcitation_count() {
return modelo.getcitation_count();
}
public void setcitation_count(String citation_count) {
this.modelo.setcitation_count(citation_count);
}
public String getaffiliation() {
return modelo.getaffiliation();
}
public void setaffiliation(String affiliation) {
this.modelo.setaffiliation(affiliation );
}
public String getgive_name() {
return modelo.getgive_name();
}
public void setgive_name(String give_name) {
this.modelo.setgive_name(give_name);
}
public String getclassification() {
return modelo.getclassification();
}
public void setclassification(String classification) {
this.modelo.setclassification(classification);
}
public String getpublication_start() {
return modelo.getpublication_start();
}
public void setpublication_start(String publication_start) {
this.modelo.setpublication_start(publication_start);
}
public String getpublication_end() {
return modelo.getpublication_end();
}
public void setpublication_end(String publication_end) {
this.modelo.setpublication_end(publication_end);
}
//pasa el modelo a la vista para presentar los datos
public void actualizarVista() {
vista.imprimirDatos(modelo.getID(),modelo.geturl(), modelo.geteid(), modelo.getdocument_count(), modelo.getcited_by_count(), modelo.getcitation_count(), modelo.getaffiliation(), modelo.getgive_name(), modelo.getclassification(), modelo.getpublication_start(), modelo.getpublication_end());
}
}
When I run it the console shows this:
****AUTOR****
ID: SCOPUS_ID:85137292444
url: null
eid: null
document_count: null
cited_by_count: null
citation_count: null
affiliation: null
The JSONArray Entrys have multiple articles, I want the program to print them all. Does anyone know what I'm doing wrong?
The JSON File is:
https://drive.google.com/file/d/1t53qiU64eJVUupDA-Ie2ZR1Xakz7npGI/view?usp=sharing

Your method mostrarInformacionEntry is reading the fields of one JSON array entry. Your problem is, that this method isn't creating a new model per entry. Instead it assigns the read value dc:identifier to the class variable ID. This is done for all entries in the array. An entry overwrites the saved ID of the previous entry. At the end you create a model with the ID of the last loaded entry. But you should create a model for each entry.
You need a custom entry class/POJO:
public class ModeloEntry {
private String ID;
private String url;
private String eid;
private String document_count;
private String cited_by_count;
private String citation_count;
private String affiliation;
private String give_name;
private String classification;
private String publication_start;
private String publication_end;
public ModeloEntry() {
}
public String getID() {
return ID;
}
public void setID(String string) {
this.ID = string;
}
public String geturl() {
return url;
}
public void seturl(String url) {
this.url = url;
}
public String geteid() {
return eid;
}
public void seteid(String eid) {
this.eid = eid;
}
public String getdocument_count() {
return document_count;
}
public void setdocument_count(String document_count) {
this.document_count = document_count;
}
public String getcited_by_count() {
return cited_by_count;
}
public void setcited_by_count(String cited_by_count) {
this.cited_by_count = cited_by_count;
}
public String getcitation_count() {
return citation_count;
}
public void setcitation_count(String citation_count) {
this.citation_count = citation_count;
}
public String getaffiliation() {
return affiliation;
}
public void setaffiliation(String affiliation) {
this.affiliation = affiliation;
}
public String getgive_name() {
return give_name;
}
public void setgive_name(String give_name) {
this.give_name = give_name;
}
public String getclassification() {
return classification;
}
public void setclassification(String classification) {
this.classification = classification;
}
public String getpublication_start() {
return publication_start;
}
public void setpublication_start(String publication_start) {
this.publication_start = publication_start;
}
public String getpublication_end() {
return publication_end;
}
public void setpublication_end(String publication_end) {
this.publication_end = publication_end;
}
}
And you need a model in the context of MVC, holding all entries:
public class Modelo {
private List<ModeloEntry> entries = new ArrayList<>();
public void addEntry(ModeloEntry entry) {
this.entries.add(entry);
}
public List<ModeloEntry> getEntries() {
return entries;
}
}
Then you can do the following:
public class Main() {
// ...
private static Modelo llenarDatosModelo() {
Modelo autor = new Modelo(); // Create the MVC model first
JSONParser jsonParser = new JSONParser ();
try(FileReader reader = new FileReader ("datos.json")) {
JSONObject documento = (JSONObject) jsonParser.parse(reader);
JSONObject resultados = (JSONObject)documento.get("search-results");
JSONArray Entrys = (JSONArray) resultados.get("entry");
for(Object Entry: Entrys) {
ModeloEntry entry = mostrarInformacionEntry ((JSONObject) Entry); // Create a entry instance per JSON array entry
author.addEntry(entry); // Add the entry to your MVC model
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch(IOException e) {
e.printStackTrace();
} catch(ParseException e) {
e.printStackTrace();
}
return autor; // Return your MVC model
}
private static ModeloEntry mostrarInformacionEntry(JSONObject entry) {
ModeloEntry entry = new ModeloEntry(); // Create a entry instance
entry.setId((String) entry.get("dc:identifier"));
return entry;
}
}
Your for-each loop is then outsourced to your controller class:
public class Controlador {
private Vista vista;
private Modelo modelo;
public void actualizarVista() {
// Print each entry of your MVC model line by line
for(ModeloEntry entry : modelo.getEntries()) {
vista.imprimirDatos(modelo.getID(),modelo.geturl(), modelo.geteid(), modelo.getdocument_count(), modelo.getcited_by_count(), modelo.getcitation_count(), modelo.getaffiliation(), modelo.getgive_name(), modelo.getclassification(), modelo.getpublication_start(), modelo.getpublication_end());
}
}
}

Java.net(RestFul service JSON reponse parsing issue) How to convert list of same item in JSON reponse String to Java Object?

I am calling Restful service using below code :(Java.net implementation )
StringBuilder responseStrBuilder = new StringBuilder();
try
{
URL url = new URL(restUrl);
conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod(httpRequestMethod);
conn.setRequestProperty("Accept-Language", "en-US,en;q=0.5");
conn.setRequestProperty("Content-Type", "application/json");
if (requestHeaders != null)
{
for (Map.Entry<String, String> entry : requestHeaders.entrySet())
{
conn.setRequestProperty(entry.getKey(), entry.getValue());
}
}
conn.setDoInput(true);
conn.setDoOutput(true);
OutputStream os = conn.getOutputStream();
os.write(urlParameters.getBytes());
os.flush();
os.close();
if (conn.getResponseCode() != 200) {//do something}
br = new BufferedReader(new InputStreamReader((conn.getInputStream())));
while ((output = br.readLine()) != null)
responseStrBuilder.append(output);
Approach 1:
I have below string(JSON String) as my Restful service response , how can I convert it to Java object. Since same(Itm) object is repeated multiple times if I use org.codehaus.jettison.json.JSONObject myObject = new org.codehaus.jettison.json.JSONObject(responseStrBuilder.toString());
It only reads first Itm Object and does not bring list of all item object.
JSON String output from service :
{"Response":{"RID":"04'34'",
"Itm":{"id":{"ab":"1","cd":"12"},"qw":"JK","name":"abcd "},
"Itm":{"id":{"ab":"2","cd":"34},"qw":"JK","name":"asdf "},
"Itm":{"id":{"ab":"3","cd":"12"},"qw":"JK","name":"fghj "}
}}
Approach 2:
I also tried below snippet with correct Java object with setters and getters
ObjectMapper objectMapper = new ObjectMapper();
mapper.configure(DeserializationConfig.Feature.FAIL_ON_UNKNOWN_PROPERTIES, false);
MyJavaReponseObject javaObj = mapper.readValue(json, MyJavaReponseObject.class);
This approach also reads only one object of Itm and not all the object as its not coming in array format in JSON string. Is there any better way of getting all the object(Itm) mapped to single List of Object in java pojo ?

You can use the List class in your response object, if you should parse that json string itself.
I have a ReponseJSON class with json objects, one Response and three Itms
static class ReponseJSON {
private Response Response;
#JsonProperty("Response")
public Response getResponse() {
return Response;
}
public void setResponse(Response Response) {
this.Response = Response;
}
static class Response {
private String rid;
private Itm Itm;
private List<Itm> listItm = new ArrayList<Itm>();
public Itm getItm() {
return Itm;
}
#JsonProperty("Itm")
public void setItm(Itm Itm) {
this.Itm = Itm;
listItm.add(Itm);
}
public String getRID() {
return rid;
}
public List<Itm> getItms() {
return listItm;
}
#JsonProperty("RID")
public void setRID(String rid) {
this.rid = rid;
}
static class Itm {
private Id id;
private String qw, name;
public String getQw() {
return qw;
}
public void setQw(String qw) {
this.qw = qw;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Id getId() {
return id;
}
public void setId(Id id) {
this.id = id;
}
static class Id {
private String ab, cd;
public String getCd() {
return cd;
}
public void setCd(String cd) {
this.cd = cd;
}
public String getAb() {
return ab;
}
public void setAb(String ab) {
this.ab = ab;
}
}
}
}
}
In a Response class, I have a list class and save a Itm object whenever object mapper call this class.
static class Response {
... skip ..
private List<Itm> listItm = new ArrayList<Itm>();
... skip ..
#JsonProperty("Itm")
public void setItm(Itm Itm) {
this.Itm = Itm;
listItm.add(Itm);
}
}
Check the full source code as follows.
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.core.JsonParseException;
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.ObjectMapper;
public class JacksonParserTest {
static class ReponseJSON {
private Response Response;
#JsonProperty("Response")
public Response getResponse() {
return Response;
}
public void setResponse(Response Response) {
this.Response = Response;
}
static class Response {
private String rid;
private Itm Itm;
private List<Itm> listItm = new ArrayList<Itm>();
public Itm getItm() {
return Itm;
}
#JsonProperty("Itm")
public void setItm(Itm Itm) {
this.Itm = Itm;
listItm.add(Itm);
}
public String getRID() {
return rid;
}
public List<Itm> getItms() {
return listItm;
}
#JsonProperty("RID")
public void setRID(String rid) {
this.rid = rid;
}
static class Itm {
private Id id;
private String qw, name;
public String getQw() {
return qw;
}
public void setQw(String qw) {
this.qw = qw;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Id getId() {
return id;
}
public void setId(Id id) {
this.id = id;
}
static class Id {
private String ab, cd;
public String getCd() {
return cd;
}
public void setCd(String cd) {
this.cd = cd;
}
public String getAb() {
return ab;
}
public void setAb(String ab) {
this.ab = ab;
}
}
}
}
}
public static void main(String[] args) {
String responseJson =
"{\"Response\":{\"RID\":\"04'34'\","
+ "\"Itm\":{\"id\":{\"ab\":\"1\",\"cd\":\"12\"},\"qw\":\"JK\",\"name\":\"abcd\"}"
+ ",\"Itm\":{\"id\":{\"ab\":\"2\",\"cd\":\"34\"},\"qw\":\"JK\",\"name\":\"asdf\"}"
+ ",\"Itm\":{\"id\":{\"ab\":\"3\",\"cd\":\"12\"},\"qw\":\"JK\",\"name\":\"fghj\"}"
+ "}} ";
ObjectMapper mapper = new ObjectMapper();
ReponseJSON responseObj = null;
try {
responseObj = mapper.readValue(responseJson, ReponseJSON.class);
ReponseJSON.Response response = responseObj.getResponse();
for(int i = 0; i < response.getItms().size(); i++)
{
ReponseJSON.Response.Itm item = response.getItms().get(i);
System.out.println(item.getId().getAb());
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
The version of my jackson mapper is 2.9.1.
You check the main method of the source, because the JSON string you prepared is invalid as coddemonkey mentioned.
Have a good day.

Make your json response looks something similar to this
{"Response":{"RID":"04'34'",
"Itms":[{"id":{"ab":"1","cd":"12"},"qw":"JK","name":"abcd "},
{"id":{"ab":"2","cd":"34"},"qw":"JK","name":"asdf "},
{"id":{"ab":"3","cd":"12"},"qw":"JK","name":"fghj "}]
}}
then, use org.json jar to parse the string to jsonObject
JSONObject jsonObject=new JSONObject(responseString);
This is one type of solution, if you can't change the response as mentioned above then you have to manually parse the string(using java bean) there is no other option available.

Empty string when using GSON for Java -> JSon

Trying to convert a POJO to a Json representation , my output is quite surprising : empty !
Here the POJO class :
public class AccountDTO extends BasicDBObject {
/**
*
*/
public static final String COLLECTION_NAME = "account-data";
private static final long serialVersionUID = 1L;
private String customerFirstName;
private String customerLastName;
private long customerId;
private String IBAN;
private float balance;
private String accountCurrency;
public AccountDTO(Account account, Customer customer) {
super();
this.customerFirstName = customer.getFirstname();
this.customerLastName = customer.getLastname();
this.customerId = customer.getCustomerId();
this.IBAN = account.getIBAN();
this.balance = account.getBalance();
this.accountCurrency = account.getAccountCurrency();
}
public String getCustomerName() {
return customerFirstName;
}
public void setCustomerName(String customerName) {
this.customerFirstName = customerName;
}
public String getCustomerLastName() {
return customerLastName;
}
public void setCustomerLastName(String customerLastName) {
this.customerLastName = customerLastName;
}
public long getCustomerId() {
return customerId;
}
public void setCustomerId(long customerId) {
this.customerId = customerId;
}
public String getIBAN() {
return IBAN;
}
public void setIBAN(String iBAN) {
IBAN = iBAN;
}
public float getBalance() {
return balance;
}
public void setBalance(float balance) {
this.balance = balance;
}
public String getCustomerFirstName() {
return customerFirstName;
}
public void setCustomerFirstName(String customerFirstName) {
this.customerFirstName = customerFirstName;
}
public String getAccountCurrency() {
return accountCurrency;
}
public void setAccountCurrency(String accountCurrency) {
this.accountCurrency = accountCurrency;
}
#Override
public String toString() {
return "AccountDTO [customerFirstName=" + customerFirstName + ", customerLastName=" + customerLastName
+ ", customerId=" + customerId + ", IBAN=" + IBAN + ", balance=" + balance + ", accountCurrency="
+ accountCurrency + "]";
}
}
The converter :
public abstract class AccountDTODigester {
public static String digestJavaToJson(AccountDTO dto){
Gson gson = new Gson();
String json = gson.toJson(dto);
return json;
}
}
Code with jackson :
public abstract class AccountDTODigester {
public static String digestJavaToJson(AccountDTO dto) throws JsonProcessingException{
ObjectMapper mapper = new ObjectMapper();
String jsonInString = new String();
jsonInString = mapper.writeValueAsString(dto);
return jsonInString;
}
}
And finnaly the runner :
public class DAOTest {
AccountDTO accountDTO;
#Before
public void initialize(){
Account account = new Account("FRkk BBBB BGGG GGCC CCCC CCCC CKK", 0, "euro");
Customer customer = new Customer("XXXXXX", "YYYYYY", 1, account);
this.accountDTO = new AccountDTO(account, customer);
}
#Test
public void toJson(){
Assert.assertNotEquals(AccountDTODigester.digestJavaToJson(accountDTO),new String("{}"));
}
Console output :
AccountDTO [customerFirstName=XXXXXX, customerLastName=YYYYYY, customerId=1, IBAN=FRkk BBBB BGGG GGCC CCCC CCCC CKK, balance=0.0, accountCurrency=euro]
{}
When I run the test, my json string is { }and my test is mark as failed.
Gson seems to ver very easy to use, I don't understand why I got this empty Json instead a String filled with a json representation of my AccountDTO object

Ok I found solution :
My JSON was null because extends BasicDBObject , the serialization seems to be jammed by this.
Still looking for a better explication, but now my json is ok.

Having difficulty to convert xml to java object

I am using XStream Library.
Link of xml service
http://webservices.nextbus.com/service/publicXMLFeed?command=routeConfig&a=ttc&r=54
My Classes......
package com.example.myjakcontest;
import java.util.List;
import com.thoughtworks.xstream.annotations.XStreamAlias;
public class Body {
#XStreamAlias("copyright")
private String _copyright;
private Route route;
public String get_copyright() {
return this._copyright;
}
public void set_copyright(String _copyright) {
this._copyright = _copyright;
}
public Route getRoute() {
return this.route;
}
public void setRoute(Route route) {
this.route = route;
}
}
package com.example.my**jakcontest;**
import java.util.List;
public class Direction{
private String _branch;
private String _name;
private String _tag;
private String _title;
private String _useForUI;
private List<Stop> stop;
public String get_branch(){
return this._branch;
}
public void set_branch(String _branch){
this._branch = _branch;
}
public String get_name(){
return this._name;
}
public void set_name(String _name){
this._name = _name;
}
public String get_tag(){
return this._tag;
}
public void set_tag(String _tag){
this._tag = _tag;
}
public String get_title(){
return this._title;
}
public void set_title(String _title){
this._title = _title;
}
public String get_useForUI(){
return this._useForUI;
}
public void set_useForUI(String _useForUI){
this._useForUI = _useForUI;
}
public List<Stop> getStop(){
return this.stop;
}
public void setStop(List<Stop> stop){
this.stop = stop;
}
}
Async Task
XStream x = new XStream();
x.alias("body", Body.class);
x.alias("stop", Stop.class);
x.alias("route", Route.class);
x.alias("direction", Direction.class);
x.alias("path", Path.class);
x.alias("point", Point.class);
x.addImplicitCollection(Route.class, "stop");
x.addImplicitCollection(Route.class, "direction");
x.addImplicitCollection(Route.class, "path");
x.addImplicitCollection(Direction.class, "stop");
x.addImplicitCollection(Path.class, "point");
Body object = (Body) x.fromXML(httpResponse.getEntity()
.getContent());
// Function converts XML to String
String xml = convertStreamToString(httpResponse.getEntity()
.getContent());
Body b = (Body) x.fromXML(xml);
I have all the classes but in object "b" i am getting null.

Try JAXB .It s a standard way of doing it...!
refer the link www.javatpoint.com/jaxb-unmarshalling-example