自定义列表视图适配器中的 clear() 也会更新列表数据

Question

我正在研究一个列表视图过滤器，也就是说，有一个编辑框，如果我输入一些关键字，列表视图数据会相应地改变。首先，有一个数据集。

private ArrayList<PostItem> postList;

假设列表中已经填满了数据，这里是带有过滤的适配器：

private class PostAdapter extends ArrayAdapter<PostItem> implements
        Filterable {

    public PostAdapter(Context context, int resource, List<PostItem> items) {
        super(context, resource, items);
    }

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

        View v = convertView;

        if (v == null) {
            LayoutInflater vi;
            vi = LayoutInflater.from(getContext());
            v = vi.inflate(R.layout.post_item, parent, false);
        }

        PostItem post = getItem(position);

        if (post != null) {
            TextView title = (TextView) v.findViewById(R.id.postTitle);
            TextView date = (TextView) v.findViewById(R.id.postDate);

            v.setTag(post.id);
            title.setText(Html.fromHtml(post.title));
            date.setText(post.name + " "
                    + getResources().getString(R.string.post_on) + " "
                    + post.date);
        }

        return v;

    }

    @Override
    public Filter getFilter() {

        Filter filter = new Filter() {

            @SuppressWarnings("unchecked")
            @Override
            protected void publishResults(CharSequence constraint,
                    FilterResults results) {

                ArrayList<PostItem> filteredList = (ArrayList<PostItem>)results.values;

                clear();

                for (PostItem item :filteredList) {
                    add(item);
                }
            }

            @Override
            protected FilterResults performFiltering(CharSequence constraint) {
                FilterResults results = new FilterResults();
                ArrayList<PostItem> filteredArray = new ArrayList<PostItem>();

                constraint = constraint.toString().toLowerCase();

                for (PostItem item : postList) {
                    if (item.title.toLowerCase().contains(constraint)) {
                        filteredArray.add(item);
                    }
                }

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

        return filter;
    }

}

问题是，clear() 函数还会删除 postList 中包含的所有项目，并插入所有最新的过滤结果。如何解决？我试图有一个复制的变量，例如copyPostList = postList 但还是一样。感谢您的帮助

更新：更多解释：

1. 首先，postList 有项目“abc”；

2. 然后，输入“ab”，列表显示“abc”，正确

3. 然后，输入“xyz”，列表什么都不显示，这是正确的

4. 最后输入“abc”，列表不显示，不正确

Answer 1

public class AutoCompleteAdapter extends ArrayAdapter<String> implements Filterable {

    private ArrayList<String> fullList;
    private ArrayList<String> mOriginalValues;
    private ArrayFilter mFilter;

    public AutoCompleteAdapter(Context context, int resource, List<String> objects) {

        super(context, resource, objects);
        fullList = (ArrayList<String>) objects;
        mOriginalValues = new ArrayList<String>(fullList);

    }

    @Override
    public void add(String object) {
        super.add(object);
        fullList.add(object);
        mOriginalValues.add(object);
    }

    @Override
    public void clear() {
        super.clear();
        fullList.clear();
        mOriginalValues.clear();
    }

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

    @Override
    public String getItem(int position) {
        return fullList.get(position);
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        TextView view = (TextView) super.getView(position, convertView, parent);
        view.setEllipsize(TextUtils.TruncateAt.START);
        return view;
    }

    @Override
    public Filter getFilter() {
        if (mFilter == null) {
            mFilter = new ArrayFilter();
        }
        return mFilter;
    }


    private class ArrayFilter extends Filter {

        @Override
        protected FilterResults performFiltering(CharSequence prefix) {
            FilterResults results = new FilterResults();

            if (mOriginalValues == null) {
                mOriginalValues = new ArrayList<String>(fullList);
            }
            ArrayList<String> list = new ArrayList<String>(mOriginalValues);
            results.values = list;
            results.count = list.size();


            return results;
        }

        @SuppressWarnings("unchecked")
        @Override
        protected void publishResults(CharSequence constraint, FilterResults results) {

            if (results.values != null) {
                fullList = (ArrayList<String>) results.values;
            } else {
                fullList = new ArrayList<String>();
            }
            if (results.count > 0) {
                notifyDataSetChanged();
            } else {
                notifyDataSetInvalidated();
            }
        }
    }
}

检查一下。这个适配器很好用。祝你好运。

Answer 2

最终代码，为我的案例添加过滤和getView

    private class PostAdapter extends ArrayAdapter<PostItem> implements Filterable {

    private ArrayList<PostItem> fullList;
    private ArrayList<PostItem> mOriginalValues;        
    private ArrayFilter mFilter;

    public PostAdapter(Context context, int resource, List<PostItem> objects) {
        super(context, resource, objects);
        fullList = (ArrayList<PostItem>) objects;
        mOriginalValues = new ArrayList<PostItem>(fullList);

    }

    @Override
    public void add(PostItem object) {
        super.add(object);
        fullList.add(object);
        mOriginalValues.add(object);
    }

    @Override
    public void clear() {
        super.clear();
        fullList.clear();
        mOriginalValues.clear();
    }

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

    @Override
    public PostItem getItem(int position) {
        return fullList.get(position);
    }

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

        View v = convertView;

        if (v == null) {
            LayoutInflater vi;
            vi = LayoutInflater.from(getContext());
            v = vi.inflate(R.layout.post_item, parent, false);
        }

        PostItem post = getItem(position);

        if (post != null) {
            TextView title = (TextView) v.findViewById(R.id.postTitle);
            TextView date = (TextView) v.findViewById(R.id.postDate);

            v.setTag(post.id);
            title.setText(Html.fromHtml(post.title));
            date.setText(post.name + " "
                    + getResources().getString(R.string.post_on) + " "
                    + post.date);
        }

        return v;
    }

    @Override
    public Filter getFilter() {
        if (mFilter == null) {
            mFilter = new ArrayFilter();
        }
        return mFilter;
    }


    private class ArrayFilter extends Filter {

        @Override
        protected FilterResults performFiltering(CharSequence prefix) {
            FilterResults results = new FilterResults();
            ArrayList<PostItem> list =  new ArrayList<PostItem>();

            if (mOriginalValues == null) {
                mOriginalValues = new ArrayList<PostItem>(fullList);
            }

            for (PostItem item : mOriginalValues) {
                if (item.title.toLowerCase().contains(prefix.toString().toLowerCase())) {
                    list.add(item);
                }
            }

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

        @SuppressWarnings("unchecked")
        @Override
        protected void publishResults(CharSequence constraint, FilterResults results) {

            if (results.values != null) {
                fullList = (ArrayList<PostItem>) results.values;
            } else {
                fullList = new ArrayList<PostItem>();
            }
            if (results.count > 0) {
                notifyDataSetChanged();
            } else {
                notifyDataSetInvalidated();
            }
        }
    }
}

感谢您的帮助