android - RecyclerView 仅在向下和向上滚动时刷新项目

Question

我正在用电影项目制作一个简单的回收 View 。当我尝试添加新项目时，它们不会立即显示在回收站 View 中。出于某种原因，我必须向下滚动以便第一个项目消失，然后再次向上滚动以显示新项目(它添加在索引 0 处)。

适配器:

public class MovieCardAdapter extends RecyclerView.Adapter<MovieCardAdapter.MovieViewHolder> {
List<Movie> movieList;

public MovieCardAdapter(final List<Movie> movieList) {
    this.movieList = movieList;
}

public void addItem(int position, final Movie movie){
    movieList.add(position,movie);
    notifyItemInserted(position);
}

public void removeItem(final Movie movie){
    final int indexOf = movieList.indexOf(movie);
    movieList.remove(movie);
    notifyItemRemoved(indexOf);
}

public void updateItems(final List<Movie> items){
    movieList = items;
    notifyDataSetChanged();
}

@Override
public MovieViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
    View itemView = LayoutInflater.
            from(viewGroup.getContext()).
            inflate(R.layout.movie_row, viewGroup, false);

    return new MovieViewHolder(itemView);
}

@Override
public long getItemId(int position) {
    return super.getItemId(position);
}

@Override
public void onBindViewHolder(final MovieViewHolder movieViewHolder, final int i) {
    final Movie movie = movieList.get(i);

    String posterUrl = "";
    final int posterHeight = 240;
    if (!isEmpty(movie.getImdb_id())) {
        posterUrl = "http://img.omdbapi.com/?i=" + movie.getImdb_id() + "&apikey="+apiKey+"&h=" + posterHeight;
    } else if (!isEmpty(movie.getPoster())) {
        posterUrl = movie.getPoster();
    }
    if (!isEmpty(posterUrl)) {
        Picasso.with(movieViewHolder.context)
                .load(posterUrl)
                .resize(220, 354)
                .centerCrop()
                .into(movieViewHolder.poster);
    }

    movieViewHolder.title.setText(movie.getTittel());
    movieViewHolder.format.setText(movie.getFormat());

    if (movie.getRuntime().isEmpty() || movie.getRuntime().equalsIgnoreCase("0")){
        movieViewHolder.runtime.setText("");
    }else{
        movieViewHolder.runtime.setText(movie.getRuntime()+" mins");
    }

    if (!movie.getTagline().isEmpty()) {
        movieViewHolder.tagline.setText(movie.getTagline());
    } else if (!movie.getPlot().isEmpty()) {
        movieViewHolder.tagline.setText(movie.getPlot());
    }
}

@Override
public int getItemCount() {
    return movieList.size();
}

public static class MovieViewHolder extends RecyclerView.ViewHolder {
    protected Context context;
    protected LinearLayout movieRowLinearLayout;
    protected ImageView poster;
    protected TextView title;
    protected TextView runtime;
    protected TextView tagline;
    protected TextView format;

    public MovieViewHolder(View v) {
        super(v);
        context = v.getContext();
        movieRowLinearLayout = (LinearLayout) v.findViewById(R.id.movieRowLinearLayout);
        poster = (ImageView) v.findViewById(R.id.poster);
        title = (TextView) v.findViewById(R.id.title);
        runtime = (TextView) v.findViewById(R.id.runtime);
        tagline = (TextView) v.findViewById(R.id.tagline);
        format = (TextView) v.findViewById(R.id.format);
    }
}

初始化适配器:

adapter = new MovieCardAdapter(MovieList.movies);
recyclerView.setAdapter(adapter);

添加示例电影:

if (id == R.id.add_movie) {
        final Movie movie = new Movie();
        movie.setTittel("0TEST");
        movie.setFormat("HD-DVD");

        MovieList.sortMoviesByTitle();
        adapter.addItem(MovieList.movies.indexOf(movie), movie);
        return true;
    } else if (id == R.id.action_logOut) {
        logOut(this);
    }

对不起英语不好，希望有人理解并知道问题可能是什么。我尝试从 runOnUiThread([...]) 添加，但结果相同。

Answer 1

发生这种情况是因为位置 0 位于当前可见屏幕上方。在实现转录模式之前，当您将项目添加到位置 N 时，如果 LinearLayoutManager#findFirstCompletelyVisibleItemPosition 返回 ，请尝试调用 scrollToPosition(N) >N.

此外，不要在 onBindViewHolder 方法中将位置参数设为 final。相反，如果您需要在回调中使用 ViewHolder.getPosition()。当项目的位置发生变化时，除非项目本身失效，否则您不会收到 onBind 调用。

更新

您的更新逻辑也不正确，因为您没有清除 View 中的值。

if (!movie.getTagline().isEmpty()) {
    movieViewHolder.tagline.setText(movie.getTagline());
} else if (!movie.getPlot().isEmpty()) {
    movieViewHolder.tagline.setText(movie.getPlot());
} else {
    movieViewHolder.tagline.setText(null);
}

海报 URL 相同。