Android – How to get tweets JSON from Twitter API?

This code uses this library: Android Asynchronous Http Client

    String url = "https://api.twitter.com/1.1/statuses/user_timeline.json?screen_name=manutd";
    AsyncHttpClient client = new AsyncHttpClient();

    private void getTweets() {

        RequestParams requestParams = new RequestParams();
        requestParams.put("grant_type", "client_credentials");
        AsyncHttpClient httpClient = new AsyncHttpClient();
        httpClient.addHeader("Authorization", "Basic " + Base64.encodeToString((CONSUMER_KEY + ":" + CONSUMER_SECRET).getBytes(), Base64.NO_WRAP));
        httpClient.addHeader("Content-Type", "application/x-www-form-urlencoded;charset=UTF-8");
        httpClient.post("https://api.twitter.com/oauth2/token", requestParams, new AsyncHttpResponseHandler() {
            @Override
            public void onSuccess(int statusCode, Header[] headers, byte[] responseBody) {
                try {
                    JSONObject jsonObject = new JSONObject(new String(responseBody));
                    client.addHeader("Authorization", jsonObject.getString("token_type") + " " + jsonObject.getString("access_token"));
                    client.get(url, handler);
                } catch (JSONException e) {
                    e.printStackTrace();
                }
            }

            @Override
            public void onFailure(int statusCode, Header[] headers, byte[] responseBody, Throwable error) {

            }

        });
    }

    AsyncHttpResponseHandler handler = new AsyncHttpResponseHandler() {
        @Override
        public void onSuccess(int statusCode, Header[] headers, byte[] responseBody) {
            String json = new String(responseBody);
            int length = json.length();
        }

        @Override
        public void onFailure(int statusCode, Header[] headers, byte[] responseBody, Throwable error) {

        }
    };