If you are using Android Studio which you should do put this line in the gradle file

compile 'com.mcxiaoke.volley:library:1.0.15'

If you want to use the GET method you should have something like that.

private void weatherData() {
    JsonObjectRequest jsonObjReq = new JsonObjectRequest(
        Request.Method.GET,
        "URL with JSON data",
        new Response.Listener<JSONObject>() {
             @Override
             public void onResponse(JSONObject response) {
                 try {
                      //Your code goes here      
                 } catch (JSONException e) {
                      Log.e("TAG", e.toString());
                 }
             }
        }, 
        new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
            }
        });
    // Adding request to request queue
    AppController.getInstance().addToRequestQueue(jsonObjReq);
}

But if you want to post data in the server,then you should construct a HashMap and Volley library converts those key/pair values into JSON objects before posting them in the server. Here is an example.

final HashMap<String, String> postParams = new HashMap<String, String>();
postParams.put("username", username);
postParams.put("password", password);

Response.Listener<JSONObject> listener;
Response.ErrorListener errorListener;
final JSONObject jsonObject = new JSONObject(postParams);

JsonObjectRequest jsonObjReq = new JsonObjectRequest(
    "YOUR URL WITH JSON DATA", 
    jsonObject,
    new com.android.volley.Response.Listener<JSONObject>() {
        @Override
        public void onResponse(JSONObject response) {
            Log.d("TAG", response.toString());
            try {
                if (response.getString("status").equals("fail")) {

                } else if (response.getString("status").equals("success")) {

                } catch (JSONException e) {
                     Log.e("TAG", e.toString())
                }
            }
        }, 
        new com.android.volley.Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
             //VolleyLog.d("TAG", "Error: " + error.getMessage());
            //pDialog.dismiss();

        }
    }) {
        @Override
        public String getBodyContentType() {
            return "application/json; charset=utf-8";
        }
    };
    // Adding request to request queue
    AppController.getInstance().addToRequestQueue(jsonObjReq, tag_json_obj);

    VolleySingleton.getInstance(getApplicationContext()).
    addToRequestQueue(jsonObjRequest);
 }