java - volley- 如何从 Volley 中的 OnResponse 方法返回 ArrayList

Question

我正在使用 volley 从 REST api 解析电影详细信息，并将解析的数据保存在名为 detailsMovies 的对象数组列表中。但是我无法在 onResponse 方法之外访问 ArrayList。我是 Android 新手，所以我不知道该怎么做。感谢您的帮助!

代码如下:`

    public class MovieDetailsActivity extends AppCompatActivity {
    TextView movieIdText;
    private VolleySingleton volleySingleton;
    private RequestQueue mRequestQueue;
    private ArrayList<MovieDetails> detailsMovies = new ArrayList<>();
//    private String movieTitle ;
//    private String movieSummary ;
//    private int movieYear;
//    private long movieRating;
//    private String movieYoutubeId;
//    private String movieUrlThumbnail;
//    private String movieDownloadLink720p;
//    private String movieQuality720p;
//    private String moviefileSize720p;
//    private String movieDownloadLink1080p;
//    private String movieQuality1080p;
//    private String moviefileSize1080p;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_movie_details);
        Intent i = getIntent();
        String movieId = i.getExtras().getString("movieId");
        volleySingleton = VolleySingleton.getsInstance();
        mRequestQueue = VolleySingleton.getmRequestQueue();
        parseMovieDetails();

    }


    public void  parseMovieDetails(){



        JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(Request.Method.GET, getUrl(100), new Response.Listener<JSONObject>() {
            @Override
            public void onResponse(JSONObject response) {
                MovieDetails movieDetails = new MovieDetails();
                if (response == null || response.length() == 0) {
                    Toast.makeText(getApplicationContext(), "Null Object", Toast.LENGTH_LONG).show();
                }

                try {

                    JSONObject movieData = response.getJSONObject("data");
                    JSONObject movieDetailsObject = movieData.getJSONObject(Keys.EndPointMovieDetails.KEYS_MOVIE);
                    String movieTitle = movieDetailsObject.getString(Keys.EndPointMovieDetails.KEYS_TITLE_LONG);
                    long movieRating = movieDetailsObject.getInt(Keys.EndPointMovieDetails.KEYS_RATING);
                    String movieSynopsis = movieDetailsObject.getString(Keys.EndPointMovieDetails.KEYS_DESCRIPTION);
                    String moviePosterUrl = movieDetailsObject.getString(Keys.EndPointMovieDetails.KEYS_COVER);
                    String movieYoutubeId = movieDetailsObject.getString(Keys.EndPointMovieDetails.KEY_YOUTUBE_ID);
                    movieDetails.setTitle(movieTitle);
                    movieDetails.setRating(movieRating);
                    movieDetails.setSummary(movieSynopsis);
                    movieDetails.setUrlThumbnail(moviePosterUrl);
                    movieDetails.setYoutube_id(movieYoutubeId);
                    detailsMovies.add(movieDetails);

                    JSONArray torrentDownloadLinks = movieDetailsObject.getJSONArray(Keys.EndPointMovieDetails.KEYS_TORRENTS);
                    for(int i=0;i<torrentDownloadLinks.length();i++) {
                        JSONObject urlInfo = torrentDownloadLinks.getJSONObject(i);
                        String urlTorrent = urlInfo.getString("url");
                        String quality = urlInfo.getString("quality");
                        String fileSize = urlInfo.getString("size");

                        movieDetails.setDownloadLink(urlTorrent);
                        movieDetails.setQuality(quality);
                        movieDetails.setFileSize(fileSize);
                        detailsMovies.add(movieDetails);
                    }



                } catch (JSONException e) {
                    e.printStackTrace();
                }


            }

        }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {

            }
        });
        mRequestQueue.add(jsonObjectRequest);



    }

    public String getUrl(int movieId){
        return UrlEndPoints.URL_MOVIE_DETAILS+
                UrlEndPoints.URl_CHAR_QUESTION+
                UrlEndPoints.URL_PARAM_ID+movieId;
    }

Answer 1

在你的类中定义一个接口(interface)并实现它。
所以这里的简单技巧是带有回调的接口(interface)。

public class MovieDetailsActivity extends AppCompatActivity { 
TextView movieIdText;
private VolleySingleton volleySingleton;
private RequestQueue mRequestQueue;
private ArrayList<MovieDetails> detailsMovies = new ArrayList<>();

@Override 
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_movie_details);
    Intent i = getIntent();
    String movieId = i.getExtras().getString("movieId");
    volleySingleton = VolleySingleton.getsInstance();
    mRequestQueue = VolleySingleton.getmRequestQueue();
    parseMovieDetails(new CallBack() {
        @Override
        public void onSuccess(ArrayList<MovieDetails> detailsMovies) {
          // Do Stuff
        }

        @Override
        public void onFail(String msg) {
            // Do Stuff
        }
    }); 

} 


public void  parseMovieDetails(final CallBack onCallBack){ 



    JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(Request.Method.GET, getUrl(100), new Response.Listener<JSONObject>() {
        @Override 
        public void onResponse(JSONObject response) {
            MovieDetails movieDetails = new MovieDetails();
            if (response == null || response.length() == 0) {
                Toast.makeText(getApplicationContext(), "Null Object", Toast.LENGTH_LONG).show();
            } 

            try { 

                JSONObject movieData = response.getJSONObject("data");
                JSONObject movieDetailsObject = movieData.getJSONObject(Keys.EndPointMovieDetails.KEYS_MOVIE);
                String movieTitle = movieDetailsObject.getString(Keys.EndPointMovieDetails.KEYS_TITLE_LONG);
                long movieRating = movieDetailsObject.getInt(Keys.EndPointMovieDetails.KEYS_RATING);
                String movieSynopsis = movieDetailsObject.getString(Keys.EndPointMovieDetails.KEYS_DESCRIPTION);
                String moviePosterUrl = movieDetailsObject.getString(Keys.EndPointMovieDetails.KEYS_COVER);
                String movieYoutubeId = movieDetailsObject.getString(Keys.EndPointMovieDetails.KEY_YOUTUBE_ID);
                movieDetails.setTitle(movieTitle);
                movieDetails.setRating(movieRating);
                movieDetails.setSummary(movieSynopsis);
                movieDetails.setUrlThumbnail(moviePosterUrl);
                movieDetails.setYoutube_id(movieYoutubeId);
                detailsMovies.add(movieDetails);

                JSONArray torrentDownloadLinks = movieDetailsObject.getJSONArray(Keys.EndPointMovieDetails.KEYS_TORRENTS);
                for(int i=0;i<torrentDownloadLinks.length();i++) {
                    JSONObject urlInfo = torrentDownloadLinks.getJSONObject(i);
                    String urlTorrent = urlInfo.getString("url");
                    String quality = urlInfo.getString("quality");
                    String fileSize = urlInfo.getString("size");

                    movieDetails.setDownloadLink(urlTorrent);
                    movieDetails.setQuality(quality);
                    movieDetails.setFileSize(fileSize);
                    detailsMovies.add(movieDetails);
                } 
               onCallBack.success(detailsMovies);


            } catch (JSONException e) {

                e.printStackTrace();
                onCallBack.onFail(e.toString());
            } 


        } 

    }, new Response.ErrorListener() {
        @Override 
        public void onErrorResponse(VolleyError error) {

        } 
    }); 
    mRequestQueue.add(jsonObjectRequest);



} 

public String getUrl(int movieId){
    return UrlEndPoints.URL_MOVIE_DETAILS+ 
            UrlEndPoints.URl_CHAR_QUESTION+ 
            UrlEndPoints.URL_PARAM_ID+movieId;
} 

 public interface CallBack {
    void onSuccess(ArrayList<MovieDetails> detailsMovies);

    void onFail(String msg);
}