不调用自定义适配器getView()方法

Question

这是片段的代码,我在其中为列表设置自定义适配器.

没有错误,但是ListView空的.我实现getCount()了在ArrayList中返回正确数量的项目.我没有("Inside", "GetView")在logcat中看到

分段

public class ServiceCarListFragment extends Fragment {

    private String url;
    private ArrayList<CarDetail> carDetailList = new ArrayList<CarDetail>();
    private CarListAdapter adapter;
    private ListView mList;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        url = getActivity().getIntent().getStringExtra("url");
        new DownloadCarDetail().execute(url);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        View v = inflater.inflate(R.layout.fragment_service_car_list, container, false);
        mList = (ListView) v.findViewById(R.id.list);
        mList.setAdapter(adapter);

        for (CarDetail car : carDetailList) {
            // START LOADING IMAGES FOR EACH STUDENT
            car.loadImage(adapter);
        }
        return v;
    }

    class DownloadCarDetail extends AsyncTask<String, String, ArrayList<CarDetail>> {

        @Override
        protected ArrayList<CarDetail> doInBackground(String... params) {
            // TODO Auto-generated method stub
            ArrayList<CarDetail> carDetailList = JsonParser.parseJson(params[0]);
            return carDetailList;
        }

        @Override
        protected void onPostExecute(ArrayList<CarDetail> carDetailList) {
            // TODO Auto-generated method stub
            ServiceCarListFragment.this.carDetailList = carDetailList;
            Log.d("dccs", String.valueOf(ServiceCarListFragment.this.carDetailList.size()));
            adapter = new CarListAdapter(getActivity(), ServiceCarListFragment.this.carDetailList);
            Log.d("dccs", String.valueOf((adapter.getCount())));
        }

    }
}

CustomAdapter

public class CarListAdapter extends BaseAdapter {

    private ArrayList<CarDetail> items = new ArrayList<CarDetail>();
    private Context context;

    public CarListAdapter(Context context, ArrayList<CarDetail> items) {
        this.context = context;
        this.items = items;
    }

    @Override
    public int getCount() {
        // TODO Auto-generated method stub
        return items.size();
    }

    @Override
    public Object getItem(int position) {
        // TODO Auto-generated method stub
        return items.get(position);
    }

    @Override
    public long getItemId(int position) {
        // TODO Auto-generated method stub
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        // TODO Auto-generated method stub
        Log.d("Inside", "GetView");
        LayoutInflater mInflater = (LayoutInflater) context.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
        ViewHolder holder = null;
        CarDetail car = items.get(position);

        if (convertView == null) {
            convertView = mInflater.inflate(R.layout.car_list_row, null);
            holder = new ViewHolder();
            holder.tvCarName = (TextView) convertView.findViewById(R.id.tvCarName);
            holder.tvDailyPriceValue = (TextView) convertView.findViewById(R.id.tvWeeklyPriceValue);
            holder.tvWeeklyPriceValue = (TextView) convertView.findViewById(R.id.tvWeeklyPriceValue);
            holder.imgCar = (ImageView) convertView.findViewById(R.id.imgCar);
            convertView.setTag(holder);
        } else {
            holder = (ViewHolder) convertView.getTag();
        }

        holder.tvCarName.setText(car.getCarName());
        if (car.getImage() != null) {
            holder.imgCar.setImageBitmap(car.getImage());
        } else {
            // MY DEFAULT IMAGE
            holder.imgCar.setImageResource(R.drawable.ic_action_call);
        }

        return convertView;
    }

    static class ViewHolder {
        TextView tvCarName;
        TextView tvDailyPriceValue;
        TextView tvWeeklyPriceValue;
        ImageView imgCar;
    }

}

Answer 1

getView没有被称为的唯一原因是:

1. getCount 返回0.
2. 你忘了打电话setAdapter了ListView.
3. 如果ListView可见性(或其容器的可见性)是GONE.感谢@TaynãBonaldo的宝贵意见.
4. ListView没有附加到任何视口布局.也就是说,mListView = new ListView(...)没有使用myLayout.addView(mListView).

在onPostExcute创建新实例后,CarListAdapter我建议您将新实例更新到您的实例ListView.确实你需要再次打电话

 mList.setAdapter(adapter);

编辑:setAdapter应始终在ui线程上调用,以避免意外行为

EDIT2:

这同样适用于RecyclerView.确保这一点

• getItemCount返回的值大于0(通常是数据集大小)
• 既setLayoutManager和setAdapter对被称为UI Thread
• 必须将窗口小部件的可见性设置为 VISIBLE

Answer 2

在向列表中添加项目时,必须验证列表是否包含元素可能有错误.要验证,请使用以下方法:

adapter.getCount();