过滤器 - 结果如何为null而不是大小为0的数组

Question

这是我的适配器中的简单过滤器类：

public class Adapter extends ArrayAdapter<T>
{
    private List<T> origItems;
    private List<T> filteredData = null;
    private ItemFilter mFilter = new ItemFilter();

    public AdapterAppOrContact(Context context, List<T> items)
    {
        super(context, R.layout.row_adapter_app, items);
        origItems = items;
        filteredData = items;
    }

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

    // ....

    private class ItemFilter extends Filter 
    {
        @Override
        protected FilterResults performFiltering(CharSequence constraint) 
        {
            String filterString = constraint.toString().toLowerCase();
            FilterResults results = new FilterResults();
            final List<T> list = origItems;
            int count = list.size();
            final ArrayList<T> newList = new ArrayList<T>(count);
            String filterableString ;

            for (int i = 0; i < count; i++)
            {
                filterableString = list.get(i).getName();
                if (filterableString.toLowerCase().contains(filterString)) 
                {
                    newList.add(list.get(i));
                }
            }

            results.values = newList;
            results.count = newList.size();
            return results;
        }

        @SuppressWarnings("unchecked")
        @Override
        protected void publishResults(CharSequence constraint, FilterResults results) 
        {
            filteredData = (ArrayList<T>) results.values;
            notifyDataSetChanged();
        }
    }
}

当您查看final ArrayList<T> newList = new ArrayList<T>(count);这意味着，就我看来，此过滤器永远不会返回null列表。但我看到以下情况：调用publishResults后，我的filteredData为空。

这怎么可能发生？ filteredData是私有的，并且在我的适配器的构造函数和过滤器的publishResults回调中的任何其他位置都不会更改。

有什么想法吗？我可以用空检查解决它，但我很好奇是什么原因

编辑 - Stacktrace

java.lang.NullPointerException: Attempt to invoke interface method 'int java.util.List.size()' on a null object reference
    at com.app.package.adapters.AdapterAppOrContact.getCount(AdapterAppOrContact.java:40)
    at android.widget.AdapterView$AdapterDataSetObserver.onChanged(AdapterView.java:828)
    at android.widget.AbsListView$AdapterDataSetObserver.onChanged(AbsListView.java:6373)
    at android.database.DataSetObservable.notifyChanged(DataSetObservable.java:37)
    at android.widget.BaseAdapter.notifyDataSetChanged(BaseAdapter.java:50)
    at android.widget.ArrayAdapter.notifyDataSetChanged(ArrayAdapter.java:310)
    at com.app.package.adapters.AdapterAppOrContact$ItemFilter.publishResults(AdapterAppOrContact.java:129)
    ...