在尝试使用我的自定义Android ArrayAdapter时，我无法弄清楚如何通过此Looper.prepare（）错误

Question

我创建了一个自定义ArrayAdapter所以我可以将结果过滤到我的AutoCompleteTextView：

public class AutoCompleteCountryAdapter extends ArrayAdapter<String>
{
    private List<String> countryListFull;

    public AutoCompleteCountryAdapter(@NonNull Context context, int resource, @NonNull List<String> countryList)
    {
        super(context, resource, countryList);
        countryListFull = new ArrayList<>(countryList);
    }

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

    private Filter countryFilter = new Filter()
    {
        @Override
        protected FilterResults performFiltering(CharSequence constraint)
        {
            FilterResults filterResults = new FilterResults();
            List<String> suggestions = new ArrayList<>();

            if (constraint == null || constraint.length() == 0)
            {
                suggestions.addAll(countryListFull);
            } else
            {
                String filterPattern = constraint.toString().toLowerCase().trim();

                for (String country : countryListFull)
                {
                    if (country.toLowerCase().startsWith(filterPattern))
                    {
                        suggestions.add(country);
                    }
                }
            }

            filterResults.values = suggestions;
            filterResults.count = suggestions.size();

            return filterResults;
        }

        @Override
        protected void publishResults(CharSequence charSequence, FilterResults filterResults)
        {
            clear();
            addAll((List) filterResults.values);
            notifyDataSetChanged();
        }

        @Override
        public CharSequence convertResultToString(Object resultValue)
        {
            return ((String) resultValue);
        }
    };
}

但是，当我尝试使用此适配器时：

List<String> placeOfBirthList;

AutoCompleteCountryAdapter pobAdapter = new AutoCompleteCountryAdapter(new AutoCompleteCountryAdapter(getApplication().getApplicationContext(), android.R.layout.simple_dropdown_item_1line, placeOfBirthList));

我收到此Logcat错误：

java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()

我在创建新Filter后第一个花括号的行中得到此异常：

private Filter countryFilter = new Filter()
{ // HERE

我不是从我的MainActivity.java中调用这个，而是从ViewModel中的一种常规方法中调用不同活动的Fragment。

public class MyViewModel extends AndroidViewModel {

    private List<String> placeOfBirthList;

    public MyViewModel(Application application) {
        super(application);
        myMethod();
    }

    private void myMethod() {
        AutoCompleteCountryAdapter myAdapter = new AutoCompleteCountryAdapter(getApplication().getApplicationContext(), android.R.layout.simple_dropdown_item_1line, placeOfBirthList);
    }
}

Answer 1

所以......我解决了这个问题。在一位同事的建议下，我将自定义ArrayAdapter的创建移动到了我的View片段中：

FragmentBinding binding = ~~~;
MyViewModel mViewModel = ~~~;
binding.setViewModel(mViewModel);
AutoCompleteCountryAdapter myAdapter = new AutoCompleteCountryAdapter(getContext(), android.R.layout.simple_dropdown_item_1line, viewModel.getPlaceOfBirthList());
binding.placeOfBirthField.setAdapter(myAdapter);

这解决了我所有的Looper问题。另外，它满足MVVM中“视图模型中没有视图代码”的要求。