NotifyDataSetChanged() 未显示更新列表

Question

我在 publishResults() 函数的过滤列表中得到了正确的对象，但是过滤后的列表没有显示在屏幕上。以下是继承自 ArrayAdapter class 的 CityAdapter class 的代码。好像 notifyDataSetChanged() 不工作？请告知为什么列表在代码中不是displaying.What的错误。


import...
public class CityListAdapter extends ArrayAdapter<City> implements Filterable {

    private ArrayList<City> cities;
    private ArrayList<City> filtered_list;

    public CityListAdapter(Context context, int resource, ArrayList<City>cities) {
        super(context, resource, cities);
        this.cities = cities;
    }

    @NonNull
    @Override
    public View getView(int position, @Nullable View convertView,  ViewGroup parent) {

        Holder holder = new Holder();
        if(convertView == null) {
            LayoutInflater inflator = LayoutInflater.from(getContext());
            convertView = inflator.inflate(R.layout.adapter_view,parent,false);


            holder.box = (CheckBox) convertView.findViewById(R.id.checkBox);
            holder.name = (TextView) convertView.findViewById(R.id.textView);

            convertView.setTag(holder);
        }
        else {
            holder = (Holder) convertView.getTag();
        }
        City city = getItem(position) ;
        holder.name.setText(city.getName());

        return convertView;
    }
    private class Holder {
        CheckBox box;
        TextView name;


    }
    @NonNull
    @Override
    public Filter getFilter() {
        return new CityFilter();
    }



    private class CityFilter extends Filter {

        @Override
        protected FilterResults performFiltering(CharSequence constraint) {

            FilterResults results = new FilterResults();

            filtered_list = new ArrayList<>();
            if (constraint != null && constraint.length()!= 0) {
                for (int i = 0; i < cities.size(); i++) {
                    if (cities.get(i).getName().contains(constraint)) {
                        filtered_list.add(cities.get(i));
                        showMessage(cities.get(i).getName() + "added");
                    }
                }
            }
            results.values = filtered_list;
            results.count = filtered_list.size();


            return results;
        }

        @Override
        protected void publishResults(CharSequence constraint, FilterResults results) {
            filtered_list = (ArrayList<City>) results.values;
            int size =filtered_list.size();
            showMessage("Data set changed"+String.format("%d", size));
            notifyDataSetChanged();
        }

    }
    public void showMessage(String message) {
        Toast toast = Toast.makeText(getContext(), message, Toast.LENGTH_LONG);
        toast.show();
    }

}

Answer 1

您需要在最开始（即在构造函数中）将完整的项目列表分配给过滤列表；这样他们就可以在没有过滤结果（空搜索）时拥有整个列表，并且只要您实例化适配器就会发生这种情况。

public CityListAdapter(Context context, int resource, ArrayList<City>cities) {
    super(context, resource, cities);
    this.cities = cities;
    this.filtered_list = cities; // <<<<< Change here
}

旁注

同时覆盖 getCount() 以避免 IndexOutOfBoundsException 当原始列表大小不等于过滤后的列表大小时滚动到列表末尾。

由于原列表为cities，过滤时，其大小会缩小，所以只需要获取过滤后的列表大小，而不是原始列表大小即可避免IndexOutOfBoundsException。

因此将其添加到适配器中：

@Override
public int getCount() {
    return filtered_list.size();
}

NotifyDataSetChanged() 未显示更新列表

NotifyDataSetChanged() isn't showing the updated list

java

android

android-arrayadapter

android-adapter