Check message send by serve with volley

I am doing some http connection trough android and server in nodejs, and in my server i have some error handling for diferent status code, what i need is to get the related message specific for the behaviour im doing.

Imagine i have some username unique error handling, if i put the same username i want to retrive the message that i already have for user handling in the server.

so my code is like this at the moment:` public void register(View view) { //defining form data

    String username = usernameTxt.getText().toString();
    String password = passwordTxt.getText().toString();
    String email = emailTxt.getText().toString();

    Map<String, String> params = new HashMap<String, String>();
    params.put("username", username);
    params.put("email", email);
    params.put("password", password);
    JsonObjectRequest request = new JsonObjectRequest(URL, new JSONObject(params),
            new Response.Listener<JSONObject>() {
                @Override
                public void onResponse(JSONObject response) {
                    Log.d("response",String.valueOf(response));
                }
            }, new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {
            NetworkResponse networkResponse = error.networkResponse;
            if (networkResponse != null && networkResponse.statusCode == 400) {
                Log.d("fail","fail");
            }
        }


    });

    request.setRetryPolicy(new DefaultRetryPolicy(60000, DefaultRetryPolicy.DEFAULT_MAX_RETRIES, DefaultRetryPolicy.DEFAULT_BACKOFF_MULT));
    queue.add(request);

}`

i can already handle the status code, but how to retrive the message for the specific error?

via Cris dois