public User setUser(string firstName, string lastName, string cpf, string password)
        {
            User user = new User();
            user.firstName = firstName;
            user.lastName = lastName;
            user.cpf = cpf;
            user.password = password;

            return user;
        }
        protected override void OnCreate(Bundle bundle)
        {
            base.OnCreate (bundle);
            SetContentView (Resource.Layout.Main);

            TextView firstName = FindViewById<TextView> (Resource.Id.firstNameField);
            TextView lastName = FindViewById<TextView> (Resource.Id.lastNameField);
            TextView cpf = FindViewById<TextView> (Resource.Id.cpfField);
            TextView password = FindViewById<TextView> (Resource.Id.passwordField);

            Button register = FindViewById<Button> (Resource.Id.RegisterButton);

            register.Click += (object sender, EventArgs e) => {

                var confirmDialog = new AlertDialog.Builder (this);

                confirmDialog.SetMessage ("Cadastrar o usuário: " + firstName.Text + "? Password " + password.Text);

                confirmDialog.SetNeutralButton ("Sim", delegate {
                    User user = new User();

                    user = setUser(firstName.Text , lastName.Text , cpf.Text, password.Text);

                    if(UserRegister.userRegister(user))
                    {
                        Toast.MakeText(this, "Usuário cadastrado com sucesso", ToastLength.Long).Show();
                    }else{
                        Toast.MakeText(this, "Erro ao cadastrar usuário", ToastLength.Long).Show();
                    }

                });

                confirmDialog.SetNegativeButton ("Não", delegate {
                });

                confirmDialog.Show();
            };

            // Set our view from the "main" layout resource

            // Get our button from the layout resource,
            // and attach an event to it
        }
        public static bool userRegister(User user)
        {
            String url = "http://10.10.15.41:8080/Futebol/rest/user/register";

            HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create (new Uri (url));
            request.ContentType = "application/json";
            request.Method = "POST";

            /* Monta o objeto json */
            using(var streamWriter = new StreamWriter(request.GetRequestStream())) {
                JsonObject json = new JsonObject();

                json.Add("firstName", user.firstName);
                json.Add("lastName", user.lastName);
                json.Add("cpf", user.cpf);
                json.Add("password", user.password);

                streamWriter.Write(json.ToString());
                streamWriter.Flush();
                streamWriter.Close();
            }

            /* Chama o serviço REST */
            try {
                HttpWebResponse response = (HttpWebResponse)request.GetResponse();
                if(response.StatusCode.Equals(HttpStatusCode.OK)){
                    return true;
                }else{
                    return false;
                }
            } catch (WebException e) {

                Console.Write("GUILHERME ERROR: ", e);
                JsonValue error = null;
                return error;

            }
        }