RecyclerView 不显示来自 JSON 的数据

Question

我正在尝试在 RecyclerView 中显示从 AirVisual API 提供的 JSON 收集的数据。但是，我遇到了一个问题，即 JSON 中的数据不会显示在 RecyclerView 中，而如果我自己向其中添加数据（通过 ArrayList），数据将显示在 RecyclerView 中。这是我从 API 解析的 JSON 数据：{  "status": "success",  "data": {    "city": "New York",    "state": "New York",    "country": "USA",    "location": {      "type": "Point",      "coordinates": [        -73.928596,        40.694401      ]    },    "current": {      "weather": {        "ts": "2018-09-12T23:00:00.000Z",        "hu": 93,        "ic": "10d",        "pr": 1024,        "tp": 23,        "wd": 102,        "ws": 2.31      },      "pollution": {        "ts": "2018-09-12T22:00:00.000Z",        "aqius": 18,        "mainus": "p2",        "aqicn": 6,        "maincn": "p2"      }    }  }} 我怀疑来自 JSON 的数据根本没有添加到 ArrayList 中，因为记录返回的 ArrayList 的大小2，这是我手动添加到列表中的 2 个对象。对于从 JSON 存储数据的Station类，我使用 jsonschema2pojo.org 生成 Gson 反序列化所需的类（不确定这是否是使用 JSON 数据的正确/最佳方式）。这是 MainActivity.javapublic class MainActivity extends AppCompatActivity {    private static final String url = "http://api.airvisual.com/v2/city?city=New%20York&state=New%20York&country=USA&key={{API_KEY}}";    private RecyclerView recyclerView;    private Adapter adapter;    private List<Station> stationList;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        RecyclerView recyclerView = (RecyclerView) findViewById(R.id.recyclerView);        recyclerView.setHasFixedSize(true);        recyclerView.setLayoutManager(new LinearLayoutManager(this));        stationList = new ArrayList<>();        loadRecyclerViewData();        //Information for these objects are in the code        //but I decided not to include it in here        //because these are just for testing        Station station1 = new Station();        Station station2 = new Station();        stationList.add(station1);        stationList.add(station2);        adapter = new Adapter(this, stationList);

Answer 1

  private void loadRecyclerViewData() { RequestQueue requestQueue = Volley.newRequestQueue(this); // Request a string response from the provided URL. StringRequest stringRequest = new StringRequest(Request.Method.GET, url, new Response.Listener<String>() { @Override public void onResponse(String response) { // Using Gson to turn JSON to Java object of Station GsonBuilder gsonBuilder = new GsonBuilder(); Gson gson = gsonBuilder.create(); Station station = gson.fromJson(response, Station.class); stationList.add(station);

adapter.notifyDataSetChanged();

Log.d("API RESPONSE", response); } }, new Response.ErrorListener() { @Override public void onErrorResponse(VolleyError error) { Log.d("VOLLEY ERROR", error.toString()); } }); // Add the request to the RequestQueue. requestQueue.add(stringRequest); }

将数据添加到数据集后，您必须调用 notifyDataSetChanged()。