Question

我的RecyclerView包含看到的电影前面的复选标记。我在对RecyclerView进行排序后使用notifyDatasetChanged()。单击菜单选项后，即使项目发生变化，复选标记也不会更改并保持在同一位置。

以下是我的活动课程的一部分：

public class SearchActivity extends AppCompatActivity {
    MoviesAdapter adapter;
    List<Movie> movies = new ArrayList<>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        adapter = new MovieAdapter(movies, SearchActivity.this);
        recyclerView.setAdapter(adapter);

        fetchMovies("ascending");
    }

    private void fetchMovies(String order) {
        movies.clear();
        movies.addAll(response.body().getMovies(order));
        adapter.notifyDatasetChanged();
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case R.id.ascending:
                fetchMovies("ascending");
                adapter.notifyDatasetChanged();
                return true;
            case R.id.descending:
                fetchMovies("descending");
                adapter.notifyDatasetChanged();                    
                return true;
            default:
                return super.onOptionsItemSelected(item);
        }
    }
}

我的MovieAdapter：

public class MovieAdapter extends RecyclerView.Adapter<MovieAdapter.MovieViewHolder> {

private List<Movie> movies;
private final int rowLayout;
private final Context context;

public MovieAdapter(List<Movie> movies, Context context) {
    this.movies= movies;
    this.rowLayout = R.layout.movie_item;
    this.context = context;
}

@Override
public MovieViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View view = LayoutInflater.from(parent.getContext()).inflate(rowLayout, parent, false);
    return  new MovieViewHolder(view);
}

@Override
public void onBindViewHolder(final MovieViewHolder holder, @SuppressLint("RecyclerView") final int position) {...}

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

@Override
public int getItemViewType(int position) {
    return position;
}

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

public void notifyNewData(List<Movie> movies) {
    this.movies= movies;
    notifyDataSetChanged();
}

static class MovieViewHolder extends RecyclerView.ViewHolder {...}

}

Answer 1

你应该使用movies.addAll（）而不是movies.add（）。因为很明显你从api响应中添加了更多的项目。

如果它不起作用，请在适配器类中创建一个方法并将新值传递给它，并从该方法中调用notifyDatasetChanged：

 public void notifyNewData(List<Movie> movies){
        this.movies.clear()
        this.addAll(movies)
        this.notifyDatasetChanged();
    }

并调用adapter.notifyNewData（movies）;来自你的主要班级

在排序RecyclerView后，notifyDatasetChanged（）无法正常工作

1 个答案: