Question

我是回收视图中的新手。这是我的RecycerView的示例代码。我从互联网获取数据，在stage.setOnCloseRequest(new EventHandler<WindowEvent>() { @Override public void handle(WindowEvent event) { System.out.println("I will not close"); event.consume(); } });我设置了适配器。

onPostExecute()

运行后，我收到此错误：

RecyclerView recycle;
MyAdapter adapters;
private static String url;
private static final String TAG_CONTACTS = "contacts";
JSONArray contacts = null;
ProgressDialog pDialog;
private int preLast;
int page = 0, in, to;
Boolean loadmore = true;
HashMap<String, String> item;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    url = "http://192.168.1.20/adres/getAds.php";

    recycle = (RecyclerView) findViewById(R.id.recycle);
    recycle.setItemAnimator(new DefaultItemAnimator());

    new GetContacts().execute();

    final GestureDetector mGestureDetector = new GestureDetector(MainActivity.this, new GestureDetector.SimpleOnGestureListener() {

        @Override
        public boolean onSingleTapUp(MotionEvent e) {
            return true;
        }

    });

}

private class GetContacts extends AsyncTask<Void, Void, ArrayList<HashMap<String, String>>> {
    Boolean goterr = false;

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        pDialog = new ProgressDialog(MainActivity.this);
        pDialog.setCancelable(true);
        pDialog.show();
    }

    @Override
    protected ArrayList<HashMap<String, String>> doInBackground(Void... arg0) {
        String jsonStr = Fun.getHtml(url);
        Log.v("this", jsonStr);
        ArrayList<HashMap<String, String>> dataC = new ArrayList<HashMap<String, String>>();

        if (jsonStr != null) {
            try {
                JSONObject jsonObj = new JSONObject(jsonStr);
                contacts = jsonObj.getJSONArray(TAG_CONTACTS);
                if (contacts.length() < 20)
                    loadmore = false;

                for (int i = 0; i < contacts.length(); i++) {
                    JSONObject c = contacts.getJSONObject(i);
                    HashMap<String, String> contact = new HashMap<String, String>();
                    contact.put("id", new String(c.getString("id").getBytes("ISO-8859-1"), "UTF-8"));
                    contact.put("name", new String(c.getString("name").getBytes("ISO-8859-1"), "UTF-8"));
                    dataC.add(contact);
                    dataC.add(contact);
                }
            } catch (JSONException e) {
                Log.v("this", e.getMessage());
                goterr = true;
            } catch (UnsupportedEncodingException e) {
                Log.v("this", e.getMessage());
                goterr = true;
            }
        } else {
            goterr = true;
        }
        return dataC;
    }

    @Override
    protected void onPostExecute(ArrayList<HashMap<String, String>> result) {
        super.onPostExecute(result);
        if (pDialog.isShowing() && pDialog != null)
            pDialog.dismiss();

        if (!isCancelled() && goterr == false && result != null) {
            if (adapters == null) {
                adapters = new MyAdapter(MainActivity.this, result);
                recycle.setAdapter(adapters);
                recycle.setLayoutManager(new LinearLayoutManager(MainActivity.this));
            } else {
                adapters.addAll(result);
            }
        } else {
            //MyToast.makeText(MainActivity.this, DariGlyphUtils.reshapeText(MainActivity.this.getResources().getString(R.string.problemload)));
        }

    }
}

public class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyViewHolder> {
    private LayoutInflater inflater;
    public ArrayList<HashMap<String, String>> list;

    public MyAdapter(Context context, ArrayList<HashMap<String, String>> list) {
        inflater = LayoutInflater.from(context);
        this.list = list;
    }

    @Override
    public MyViewHolder onCreateViewHolder(ViewGroup parrent, int i) {
        View view = inflater.inflate(R.layout.customrow, parrent, false);
        MyViewHolder holder = new MyViewHolder(view);
        return holder;
    }

    public void addAll(ArrayList<HashMap<String, String>> result) {
        if (this.list == null) {
            this.list = result;
        } else {
            this.list.addAll(result);
        }
        notifyDataSetChanged();
    }

    public HashMap<String, String> geting(int position) {
        return list.get(position);
    }

    @Override
    public void onBindViewHolder(MyViewHolder viewHolder, int position) {
        item = list.get(position);
        viewHolder.txt.setText(item.get("onvan"));
    }

    @Override
    public int getItemCount() {
        return list.size();
    }

    class MyViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
        TextView txt;
        ImageView img;

        public MyViewHolder(View itemView) {
            super(itemView);
            itemView.setOnClickListener(this);
            txt = (TextView) itemView.findViewById(R.id.txt);
            img = (ImageView) itemView.findViewById(R.id.img);
        }

        @Override
        public void onClick(View v) {
            item = adapters.geting(getPosition());
            Log.v("this", "id " + item.get("id"));
            /*Intent in=new Intent (FistActiivty.this,AdDetails.class);
            in.putExtra("ad_id",item.get("id"));
            startActivity(in)*/
            ;

        }
    }
}

这段代码有什么问题？

Answer 1

问题是在第一次布局过程中，当您的AsyncTask仍在从网络获取数据时，您的RecyclerView没有适配器。

您可以在onCreate()中附加（空）适配器，并在onPostExecute()中更新适配器的数据。只需确保适配器正确处理空数据集。

没有适配器;使用RecyclerView时跳过布局

1 个答案: