Xml is working fine but json is not in jax rs - api

Question

I am learning restful api with jax rs(jersey) and I making a messageResource class in which I am getting messages .everything works fine with xml but get function is not working with json .I have tried content type and accept headers too but its not working and returning 500 error and content type text/html.
Even the maven dependency moxy is also set in pom.xml
Can anybody help me finding the error.
package org.restfulapi.messenger.resources;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.ArrayList;
import java.util.List;
import javax.ws.rs.Consumes;
import javax.ws.rs.DELETE;
import javax.ws.rs.GET;
import javax.ws.rs.POST;
import javax.ws.rs.PUT;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.Produces;
import javax.ws.rs.QueryParam;
import javax.ws.rs.core.Context;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;
import javax.ws.rs.core.Response.Status;
import javax.ws.rs.core.UriInfo;
import org.restfulapi.messenger.services.DataNotFoundException;
import org.restfulapi.messenger.services.Link;
import org.restfulapi.messenger.services.Message;
import org.restfulapi.messenger.services.MessageService;
#Path("messages")
#Produces(value= {MediaType.APPLICATION_JSON,MediaType.APPLICATION_XML})
#Consumes(value= {MediaType.APPLICATION_JSON,MediaType.APPLICATION_XML})
public class MessageResource
{
MessageService service=new MessageService();
#GET
#Path("/{messageID}")
public Message getMessage(#PathParam("messageID")int id,#Context UriInfo uriinfo )
{
Message msg=service.getMessage(id);
if(service.getMessage(id)==null)
{
throw new DataNotFoundException("message with id "+id+"not found");
}
return msg;
}
#GET
public List<Message> getMessages(#QueryParam("year")int year,
#QueryParam("start") int start,
#QueryParam("size") int size)
{
if(year>0)
{
return service.getbyyear(year);
}
if(start>0 & size>0)
{
return service.get(start, size);
}
return service.getMessages();
}
#POST
public Response addMessage(Message msg) throws URISyntaxException
{
return Response.created(new URI("/messenger/webapi/messages"+msg.getId())).entity(service.addMessage(msg)).build();
}
package org.restfulapi.messenger.services;
import java.util.List;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.HashMap;
import java.util.Map;
public class MessageService {
private HashMap<Integer, Message> messages = Database.getMessages();
public MessageService()
{
}
public ArrayList<Message> getMessages() {
return new ArrayList<Message>(messages.values());
}
;
public Message getMessage(int id) {
return messages.get(id);
}
public ArrayList<Message> getbyyear(int year)
{
ArrayList<Message> result =new ArrayList();
Calendar cal=Calendar.getInstance();
for(Message msg:messages.values())
{
cal.setTime(msg.getCreated());
if(cal.get(Calendar.YEAR)==year)
result.add(msg);
}
return result;
}
public List<Message> get(int start,int size)
{
ArrayList<Message> result =new ArrayList<Message>(messages.values());
return result.subList(start, start+size);
}
public Message addMessage(Message message) {
message.setId(messages.size() + 1);
messages.put(message.getId(), message);
return message;
}
}
package org.restfulapi.messenger.services;
import java.util.ArrayList;
import java.util.Date;
import javax.xml.bind.annotation.XmlRootElement;
#XmlRootElement
public class Message {
private int id;
private String msg;
private Date created;
private String author;
private ArrayList<Link> links=new ArrayList();
public ArrayList<Link> getLinks() {
return links;
}
public void setLinks(ArrayList<Link> links) {
this.links = links;
}
public Message()
{
}
public Message(int id, String msg, String author) {
this.id = id;
this.msg = msg;
this.author = author;
this.created = new Date();
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getMsg() {
return msg;
}
public void setMsg(String msg) {
this.msg = msg;
}
public Date getCreated() {
return created;
}
public void setCreated(Date created) {
this.created = created;
}
public String getAuthor() {
return author;
}
public void setAuthor(String author) {
this.author = author;
}
public void addLink(String uri, String rel) {
Link l=new Link(uri,rel);
links.add(l);
}
}
public class Database
{
private static HashMap<Integer,Message> messages=new HashMap();
public static HashMap<Integer,Message> getMessages()
{
return messages;
}
}