Error 415 Unsupported Media Type: POST not reaching REST if JSON, but it does if XML

I am actually new to REST WS but really I don't get this 415 Unsupported Media Type.

I am testing my REST with Poster on Firefox and the GET works fine for me, also the POST (when it's a application/xml) but when I try application/json it doesn't not reach the WS at all, the server rejects it.

This is my URL: http:// localhost:8081/RestDemo/services/customers/add

This is JSON I'm sending: {"name": "test1", "address" :"test2"}

This is XML I'm sending:

<customer><name>test1</name><address>test2</address></customer>

and this is my Resource class:

@Produces("application/xml")@Path("customers")@Singleton@XmlRootElement(name = "customers")public class CustomerResource {    private TreeMap<Integer, Customer> customerMap = new TreeMap<Integer, Customer>();    public  CustomerResource() {        // hardcode a single customer into the database for demonstration        // purposes        Customer customer = new Customer();        customer.setName("Harold Abernathy");        customer.setAddress("Sheffield, UK");        addCustomer(customer);    }    @GET    @XmlElement(name = "customer")    public List<Customer> getCustomers() {        List<Customer> customers = new ArrayList<Customer>();        customers.addAll(customerMap.values());        return customers;    }    @GET    @Path("/{id}")    @Produces("application/json")    public String getCustomer(@PathParam("id") int cId) {        Customer customer = customerMap.get(cId);         return  "{\"name\": \""+ customer.getName() +" \", \"address\": \""+ customer.getAddress() +"\"}";    }    @POST    @Path("/add")    @Produces(MediaType.APPLICATION_JSON)    @Consumes({MediaType.APPLICATION_XML, MediaType.APPLICATION_JSON})    public String addCustomer(Customer customer) {         //insert          int id = customerMap.size();         customer.setId(id);         customerMap.put(id, customer);         //get inserted         Customer result = customerMap.get(id);         return  "{\"id\": \""+ result.getId() +" \", \"name\": \""+ result.getName() +" \", \"address\": \""+ result.getAddress() +"\"}";    }}

EDIT 1:

This is my Customer class:

@XmlRootElement public class Customer implements Serializable {    private int id;    private String name;    private String address;    public Customer() {    }    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;    }    public String getAddress() {        return address;    }    public void setAddress(String address) {        this.address = address;    }}