以下是我将自定义适配器设置到列表中的片段代码。
没有错误,但ListView
为空。我已经实现了getCount()
,它返回了我的ArrayList中正确数量的项目。我没有在logcat中看到("Inside", "GetView")
片段
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;
}
}
答案 0 :(得分:153)
getView
未被调用的唯一原因是:
getCount
返回0. setAdapter
上致电ListView
。ListView
的可见性(或其容器的可见性)为GONE
。感谢@TaynãBonaldo的宝贵意见。ListView
未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
中,在您创建CarListAdapter
的新实例后,我建议您将新实例更新为ListView
。确实你需要再次打电话
mList.setAdapter(adapter);
编辑:应始终在ui线程上调用setAdapter
,以避免意外行为
<强> EDIT2:强>
同样适用于RecyclerView
。确保
getItemCount
返回的值大于0
(通常是数据集大小)setLayoutManager
setAdapter
和UI Thread
VISIBLE
答案 1 :(得分:5)
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();
答案 2 :(得分:3)
我遇到了类似的问题。这是一个简单的解决方法:
在onCreateView中,您必须在创建视图之前等待。所以改变你的界限:
mList = (ListView)v.findViewById(R.id.list);
mList.setAdapter(adapter);
改变以上两条线:
mList = (ListView)v.findViewById(R.id.list);
mList.post(new Runnable() {
public void run() {
mList.setAdapter(adapter);
}
});
希望这会有助于遇到类似问题的其他人
答案 3 :(得分:0)
您缺少构造函数中的超类。请参阅下面的示例:
public AppDataAdapter(Activity a, int textViewResourceId, ArrayList<AppData> entries) {
super(a, textViewResourceId, entries);
this.entries = entries;
this.activity = a;
}
答案 4 :(得分:0)
你一直在做的是
在适配器中
public CarListAdapter(Context context , ArrayList<CarDetail> items) {
this.context = context;
this.items = items;
}
片段中的
adapter = new CarListAdapter(getActivity(),ServiceCarListFragment.this.carDetailList);
我希望您将使用FragmentActivity
您需要致电
adapter = new CarListAdapter(YOUR_ACTIVITY_CONTEXT, carDetailList);
其中YOUR_ACTIVITY_CONTEXT
将是您的FragmentActivity
答案 5 :(得分:0)
我有同样的问题。在尝试了以上所有技巧之后,我的getView仍然没有被调用。因此,我尝试删除在ListView之外使用的ScrollView。然后,getView运行良好。只是为了增加一个可能性。我希望可以帮助某人。