notifyDataSetChanged on RecyclerView

Question

我有recyclerView和customAdaprer。我将一个对象(EarthquakeList)的列表传递给回收适配器，然后执行setAdapter：

    protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    ButterKnife.bind(this);
    earthquakeList = new ArrayList<>();
    adapter = new RecyclerViewAdapter(earthquakeList);
    recyclerView.setAdapter(adapter);
}

我在AsyncTask方法上创建了onResume：

    @Override
protected void onResume() {
    super.onResume();
    // Kick off an {@link AsyncTask} to perform the network request
    new EarthQuakeAsyncTask().execute();
}

在AsyncTask我的类中，我从我的对象那里得到了一个新的列表，当我用旧的列表替换这个新的列表并调用notifyDataSetChanged时，recyclerView仍然没有显示什么？我调试我的应用程序，并从网络中获取对象。我在列表视图上这样做，但是recylerview看起来很出众。

我用新的单子代替旧的单子，一个像blow一样：

  private class EarthQuakeAsyncTask extends AsyncTask<Void, Void,  List<Earthquake>> {
    @Override
    protected List<Earthquake> doInBackground(Void... urls) {

        // Create URL object
        URL url = HttpRequest.createUrl(USGS_REQUEST_URL);

        //  perform HTTP request to the URL and receive a JSON response back
        String jsonResponse = "";
        try {
            jsonResponse = HttpRequest.makeHttpRequest(url);
        } catch (IOException e) {
            e.printStackTrace();
        }
        List<Earthquake> earthquakes = HttpRequest.extractFeaturesFromJson(jsonResponse);
        return earthquakes;
    }

    @Override
    protected void onPostExecute(List<Earthquake> earthquakeList) {
        super.onPostExecute(earthquakeList);
        MainActivity.this.earthquakeList.clear();
        MainActivity.this.earthquakeList.addAll(earthquakeList);
        adapter.notifyDataSetChanged();

    }

我到底是怎么了？

*编辑*这是适配器：

public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.MyHolder> {

List<Earthquake> earthquakes;


public RecyclerViewAdapter(List<Earthquake> earthquakes) {
    this.earthquakes = earthquakes;
}


@Override
public MyHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View view = LayoutInflater.from(parent.getContext()).inflate(
            R.layout.earthquak_list_item, parent, false);
    MyHolder myHolder = new MyHolder(view);
    return myHolder;
}

@Override
public void onBindViewHolder(MyHolder holder, int position) {

    Earthquake earthquake = earthquakes.get(position);
    holder.magnitude.setText(earthquake.getmMagnitude());
    holder.location.setText(earthquake.getmLocation());
    holder.time.setText(earthquake.getmDate());

}

@Override
public int getItemCount() {
    return (null != earthquakes ? earthquakes.size() : 0);
}

public void setItems(List<Earthquake> earthquakeList) {
    this.earthquakes = earthquakeList;

}


public class MyHolder extends RecyclerView.ViewHolder {

    @BindView(R.id.magnitude)
    TextView magnitude;

    @BindView(R.id.location)
    TextView location;

    @BindView(R.id.date)
    TextView time;

    public MyHolder(View itemView) {
        super(itemView);
        ButterKnife.bind(this, itemView);
    }
}

Answer 1

我忘了把LayoutManager放在recyclerView上了。

这是正确的代码：

    protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    ButterKnife.bind(this);
    earthquakeList = new ArrayList<>();
    layoutManager = new LinearLayoutManager(this);
    recyclerView.setLayoutManager(layoutManager);
    adapter = new RecyclerViewAdapter(earthquakeList);
    recyclerView.setAdapter(adapter);

}