Member Variable not initializing in MainActivity.java due to not waiting to finish a method. Help

    public class MainActivity extends AppCompatActivity {

    private List<Game> gameList;
    private NBA mNBA= new NBA();
    public static final String TAG = MainActivity.class.getSimpleName();
    public static final String mScoreboardUrl = "http://data.nba.com/5s/json/cms/noseason/scoreboard/20160116/games.json";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.content_main);
        RecyclerView recList = (RecyclerView) findViewById(R.id.cardList);
        recList.setHasFixedSize(true);
        LinearLayoutManager llm = new LinearLayoutManager(this);
        llm.setOrientation(LinearLayoutManager.VERTICAL);
        recList.setLayoutManager(llm);
        setUpGames();
        Log.i(TAG, "is it empty main thread " + mNBA.getGameList().size());

        GameAdapter ca = new GameAdapter(mNBA.getGameList());
        recList.setAdapter(ca);
    }



    private void setUpGames() {
        if (isNetworkAvailable()) {
            OkHttpClient client = new OkHttpClient();
            Request request = new Request.Builder().url(mScoreboardUrl).build();
            Call call = client.newCall(request);
            call.enqueue(new Callback() {
                @Override
                public void onFailure(Request request, IOException e) {
                    alertUserAboutError();
                }

                @Override
                public void onResponse(Response response) throws IOException {
                    try {
                        String jsonData = response.body().string();
                        if (response.isSuccessful()) {
                            mNBA = parseNBADetails(jsonData);
                            Log.i(TAG, "is it empty 3 " + mNBA.getGameList().size());
                        } else {
                            alertUserAboutError();
                        }
                    } catch (IOException e) {
                    } catch (JSONException j) {
                    }
                }
            });
        } else {
            Toast.makeText(this, getString(R.string.network_unavailable_message),
                    Toast.LENGTH_LONG).show();
        }
    }


    private void alertUserAboutError() {
        AlertDialogFragment dialog = new AlertDialogFragment();
        dialog.show(getFragmentManager(), "error_dialog");
    }

    private boolean isNetworkAvailable() {
        ConnectivityManager manager = (ConnectivityManager)
                getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo networkInfo = manager.getActiveNetworkInfo();
        boolean isAvailable = false;
        if (networkInfo != null && networkInfo.isConnected()) {
            isAvailable = true;
        }

        return isAvailable;

    }

    private NBA parseNBADetails(String jsonData) throws JSONException {

        NBA nba = new NBA();
        nba.setGameList(parseGames(jsonData));

        Log.i(TAG, "is it empty 2 " + nba.getGameList().size());
        return nba;
    }

    private List<Game> parseGames(String jsonData) throws JSONException {
        JSONObject sports_content = new JSONObject(jsonData);
        JSONObject schedule = sports_content.getJSONObject("sports_content");
        JSONObject gameArray = schedule.getJSONObject("games");
        JSONArray data = gameArray.getJSONArray("game");

        List<Game> gameList = new ArrayList<Game>();
        for (int i = 0; i < data.length(); i++) {
            Game game = new Game();
            JSONObject jsonGame = data.getJSONObject(i);

            JSONObject jsonVisitor = jsonGame.getJSONObject("visitor");
            game.setVisitorTeamName(jsonVisitor.getString("nickname"));
            game.setVisitorScore(jsonVisitor.getInt("score"));
            game.setVisitorTeamLocation(jsonVisitor.getString("city"));

            JSONObject jsonHome = jsonGame.getJSONObject("home");
            game.setHomeTeamLocation(jsonHome.getString("city"));
            game.setHomeTeamName(jsonHome.getString("nickname"));
            game.setHomeScore(jsonHome.getInt("score"));

            Log.i(TAG, game.getHomeScore() + "");

            gameList.add(game);
        }
        return gameList;
    }
    }