public interface ResultListener {
    public void onResult(JSONObject result);
}

private ResultListener listener;

public JSONObject logar(final String usuario , final String senha){
    Map<String, String> postParam= new HashMap<String, String>();
    postParam.put("username", usuario);
    postParam.put("password", senha);



    JsonObjectRequest jsonObjReq = new JsonObjectRequest(Request.Method.POST,
            "http://192.168.0.13:8088/onblox/login", new JSONObject(postParam),
            new Response.Listener<JSONObject>() {

                @Override
                public void onResponse(JSONObject response) {
                    Log.d("tag", response.toString());
                    Toast.makeText(getApplicationContext(), response.toString(), Toast.LENGTH_LONG).show();
                    listener.onResult(response);
                }
            }, new Response.ErrorListener() {

        @Override
        public void onErrorResponse(VolleyError error) {
            VolleyLog.d("tag" , "Error: " + error.getMessage());
            Toast.makeText(getApplicationContext(),error.getMessage().toString(), Toast.LENGTH_LONG).show();

        }
    }) {

    };

    jsonObjReq.setTag("TAG");
    // Adding request to request queue
    rq.add(jsonObjReq);

    MainActivity objectLoader = new MainActivity();

    return (JSONObject)listener;
}
public void setResultListener(ResultListener listener){
    this.listener = listener;
}