Question

我试图创建一个电影应用，所以我创建了recycleview以使用api json数据网络在gridlayout中显示海报现在该应用程序获取电影的名称和它的受欢迎程度没有问题，但无法获取海报，当我调试应用程序时，我发现海报null的值，当涉及到onbindviewholder为什么？

这是recycleview的适配器：

public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.RecyclerViewHolder> {

    ArrayList<MovieItem> mMoviesItems;
    private Context context;

    public RecyclerViewAdapter() {

    }

    class RecyclerViewHolder extends RecyclerView.ViewHolder {

        public final TextView MoviePopularity;
        public final ImageView MoviePoster;
        public final TextView MovieName;

        public RecyclerViewHolder(View view) {
            super(view);
            MoviePopularity = (TextView)itemView.findViewById(R.id.movie_popularity);
            MoviePoster = (ImageView)itemView.findViewById(R.id.iv_item_movie);
            MovieName = (TextView)itemView.findViewById(R.id.movie_name);
        }
    }

    @Override
    public RecyclerViewHolder onCreateViewHolder(ViewGroup viewGroup, int viewType) {
        context = viewGroup.getContext();
        int layoutIdForListItem = R.layout.movie_list_item;
        LayoutInflater inflater = LayoutInflater.from(context);
        boolean shouldAttachToParentImmediately = false;

        View view = inflater.inflate(layoutIdForListItem, viewGroup, shouldAttachToParentImmediately);
        return new RecyclerViewHolder(view);

    }

    @Override
    public void onBindViewHolder(RecyclerViewHolder holder, int position) {
        holder.MoviePopularity.setText(String.valueOf(mMoviesItems.get(position).getPopularity()));
        Picasso.with(this.context).load(mMoviesItems.get(position).getPhoto()).into(holder.MoviePoster);
        holder.MovieName.setText(String.valueOf(mMoviesItems.get(position).getName()));
    }


    @Override
    public int getItemCount() {
        if (null == mMoviesItems)
            return 0;
        else {
            return mMoviesItems.size();
        }
    }

    public void setMovieData(ArrayList<MovieItem> movieData) {
        mMoviesItems = movieData;
        notifyDataSetChanged();
    }

}

这是自定义类：

public class MovieItem {
    private double popularity;
    private String photo;
    private String name;

    public MovieItem(double popularity, String poster_path, String original_title) {
        this.popularity = popularity;
        this.photo = poster_path;
        this.name = original_title;
    }

    public double getPopularity() { return popularity; }
    public String getPhoto() { return photo; }
    public String getName() { return name; }
}

这是json类：公共决赛班OpenMovieJsonUtils {

    public static ArrayList<MovieItem> getSimpleMovieStringsFromJson(Context context, String moviesJsonString)
            throws JSONException {

        final String RESULTS = "results";
        final String POPULARITY = "popularity";
        final String POSTER_PATH = "poster_path";
        final String ORIGINAL_TITLE = "original_title";

        ArrayList<MovieItem> parsedMovieData = new ArrayList<MovieItem>();

        JSONObject moviesObject = new JSONObject(moviesJsonString);
        JSONArray moviesArray = moviesObject.getJSONArray(RESULTS);

        for (int i = 0; i < moviesArray.length(); i++) {
            double popularity;
            String poster_path;
            String original_title;

            moviesObject = moviesArray.getJSONObject(i);

            popularity = moviesObject.getDouble(POPULARITY);
            poster_path = moviesObject.getString(POSTER_PATH);
            original_title = moviesObject.getString(ORIGINAL_TITLE);

            parsedMovieData.add(new MovieItem(popularity, poster_path, original_title));

        }

        return parsedMovieData;
    }
}

这是网络课程：

public final class NetworkUtils {

    private static final String TAG = NetworkUtils.class.getSimpleName();

    private static final String MOVIES_BASE_URL = "https://api.themoviedb.org/3/movie/";
    private static final String MOVIES_URL  = MOVIES_BASE_URL;
    private static final String apiKey = "36666cbb5d7e20041e705d1b2c4e7a79";

    final static String API_PARAM = "api_key";

    public static URL buildUrl(String MoviesQuery) {
        Uri builtUri = Uri.parse(MOVIES_URL).buildUpon()
                .appendPath(MoviesQuery)
                .appendQueryParameter(API_PARAM, apiKey)
                .build();

        URL url = null;
        try {
            url = new URL(builtUri.toString());
        } catch (MalformedURLException e) {
            e.printStackTrace();
        }

        Log.v(TAG, "Built URI " + url);
        return url;
    }

    public static String getResponseFromHttpUrl(URL url) throws IOException {
        HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
        try {
            InputStream in = urlConnection.getInputStream();

            Scanner scanner = new Scanner(in);
            scanner.useDelimiter("\\A");

            boolean hasInput = scanner.hasNext();
            if (hasInput) {
                return scanner.next();
            } else {
                return null;
            }
        } finally {
            urlConnection.disconnect();
        }
    }
}

图像有什么问题，所以我的值为null，而不是电影的受欢迎程度和名称，而不是null

Answer 1

您的问题不完整，没有详细说明您获取API响应的详细信息。

我可以回答这个问题，因为我刚刚在Udacity正在进行的Android Developer Nanodegree中完成了这个项目。

希望你从TMDB获取电影细节。

您应该仔细阅读项目实施指南

您需要在此相对路径之前附加基本路径，以构建使用Picasso获取图像所需的完整网址

以下代码可以帮助您 -

public class MovieItem {
    private double popularity;
    private String photo;
    private String name;

    public MovieItem(double popularity, String poster_path, String original_title) {
        this.popularity = popularity;
        this.photo = poster_path;
        this.name = original_title;
    }

    public double getPopularity() { return popularity; }
    public String getPhoto() { return photo; }
    public String getName() { return name; }

    public Uri getFullPosterPath() {
        return Uri.parse("http://image.tmdb.org/t/p/")
                .buildUpon()
                .appendPath("w185")
                .appendEncodedPath(getPhoto())
                .build();
    }
}

在适配器中进行此更改 -

@Override
    public void onBindViewHolder(RecyclerViewHolder holder, int position) {
        holder.MoviePopularity.setText(String.valueOf(mMoviesItems.get(position).getPopularity()));
        Picasso.with(this.context).load(mMoviesItems.get(position).getFullPosterPath()).into(holder.MoviePoster);
        holder.MovieName.setText(String.valueOf(mMoviesItems.get(position).getName()));
    }

使用picasso从json数据中获取图像时的null值

1 个答案: