当我手动将自定义对象添加到列表中时，RecyclerView 使用自定义对象，但当我使用来自 RESTful 服务的数据实例化它时却不行
RecyclerView works with custom object when I add it to the list manually, but not when I instantiate it with data from RESTful service
我正在 Android Studio 中进行一个项目，我需要在 RecyclerView 中列出几部电影（在本例中，来自 RESTful API 数意味着 20）。现在我已经设置好一切，我的静态虚拟内容使用 cardview 显示在 recyclerview 中。然而，当我切换到它时，我的真实数据（来自 RESTful API）有问题。这是我的 MainActivity.java 带有手动数据的代码（显示数据时）：
public class MainActivity extends RecyclerViewActivity {
private static List<Film> listFilm;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setLayoutManager(new LinearLayoutManager(this));
setAdapter(new FilmAdapter());
listFilm = new ArrayList<>();
listFilm.add(new Film("Star Wars", "Princess Leia is captured and held hostage by the evil Imperial forces in their effort to take over the galactic Empire. Venturesome Luke Skywalker and dashing captain Han Solo team together with the loveable robot duo R2-D2 and C-3PO to rescue the beautiful princess and restore peace and justice in the Empire."));
listFilm.add(new Film("E.T. the Extra-Terrestrial", "A science fiction fairytale about an extra-terrestrial who is left behind on Earth and is found by a young boy who befriends him. This heart-warming fantasy from Director Steven Spielberg became one of the most commercially successful films of all time."));
listFilm.add(new Film("Jurassic Park", "A wealthy entrepreneur secretly creates a theme park featuring living dinosaurs drawn from prehistoric DNA. Before opening day, he invites a team of experts and his two eager grandchildren to experience the park and help calm anxious investors. However, the park is anything but amusing as the security systems go off-line and the dinosaurs escape."));
listFilm.add(new Film("The Lion King", "A young lion cub named Simba can't wait to be king. But his uncle craves the title for himself and will stop at nothing to get it."));
listFilm.add(new Film("Independence Day", "On July 2, a giant alien mothership enters orbit around Earth and deploys several dozen saucer-shaped 'destroyer' spacecraft that quickly lay waste to major cities around the planet. On July 3, the United States conducts a coordinated counterattack that fails. On July 4 the a plan is devised to gain access to the interior of the alien mothership in space in order to plant a nuclear missile."));
listFilm.add(new Film("Titanic", "84 years later, a 101-year-old woman named Rose DeWitt Bukater tells the story to her granddaughter Lizzy Calvert, Brock Lovett, Lewis Bodine, Bobby Buell and Anatoly Mikailavich on the Keldysh about her life set in April 10th 1912, on a ship called Titanic when young Rose boards the departing ship with the upper-class passengers and her mother, Ruth DeWitt Bukater, and her fiancé, Caledon Hockley. Meanwhile, a drifter and artist named Jack Dawson and his best friend Fabrizio De Rossi win third-class tickets to the ship in a game. And she explains the whole story from departure until the death of Titanic on its first and last voyage April 15th, 1912 at 2:20 in the morning."));
listFilm.add(new Film("Star Wars: Episode I - The Phantom Menace", "Anakin Skywalker, a young slave strong with the Force, is discovered on Tatooine. Meanwhile, the evil Sith have returned, enacting their plot for revenge against the Jedi."));
listFilm.add(new Film("Harry Potter and the Philosopher's Stone", "Harry Potter has lived under the stairs at his aunt and uncle's house his whole life. But on his 11th birthday, he learns he's a powerful wizard -- with a place waiting for him at the Hogwarts School of Witchcraft and Wizardry. As he learns to harness his newfound powers with the help of the school's kindly headmaster, Harry uncovers the truth about his parents' deaths -- and about the villain who's to blame."));
listFilm.add(new Film("The Lord of the Rings: The Fellowship of the Ring", "Young hobbit Frodo Baggins, after inheriting a mysterious ring from his uncle Bilbo, must leave his home in order to keep it from falling into the hands of its evil creator. Along the way, a fellowship is formed to protect the ringbearer and make sure that the ring arrives at its final destination: Mt. Doom, the only place where it can be destroyed."));
listFilm.add(new Film("Spider-Man", "After being bitten by a genetically altered spider, nerdy high school student Peter Parker is endowed with amazing powers."));
}
电影模型的适配器是：
private class FilmAdapter extends RecyclerView.Adapter<RowHolder> {
Context context;
public Context getContext() {
return this.context;
}
@Override
public RowHolder onCreateViewHolder(ViewGroup parent, int viewType) {
return new RowHolder(getLayoutInflater().inflate(R.layout.row, parent, false));
}
@Override
public void onBindViewHolder(RowHolder holder, int position) {
Film movie = listFilm.get(position);
TextView title = holder.title;
title.setText(movie.getTitle());
TextView desc = holder.desc;
desc.setText(movie.getDescription());
ImageView poster = holder.poster;
Picasso.with(getApplicationContext()).load("http://cdn2-www.comingsoon.net/assets/uploads/2015/03/avengersorder5.jpg").into(poster);
}
@Override
public int getItemCount() {
return listFilm.size();
}
}
而 ViewHolder class 是：
private class RowHolder extends RecyclerView.ViewHolder {
TextView title = null;
TextView desc = null;
ImageView poster = null;
public RowHolder(View itemView) {
super(itemView);
title = (TextView) itemView.findViewById(R.id.title);
desc = (TextView) itemView.findViewById(R.id.desc);
poster = (ImageView) itemView.findViewById(R.id.poster);
}
}
联系我的 RESTful API MainActivity.java 时看起来像：
public class MainActivity 扩展了 RecyclerViewActivity {
private static List<Film> listFilm;
public static final String apiURL = "https://api.themoviedb.org/4/list/10?page=1&api_key=8e20230f25939a349c2e37680cdaff95&sort_by=release_date.asc";
private JSONObject jsonObject;
private JSONArray jsonArray;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setLayoutManager(new LinearLayoutManager(this));
setAdapter(new FilmAdapter());
listFilm = new ArrayList<>();
RequestQueue queue = Volley.newRequestQueue(this);
StringRequest stringRequest = new StringRequest(Method.GET, apiURL,
new Response.Listener<String>() {
@Override
public void onResponse(String response) {
Toast.makeText(getApplicationContext(), "RADI", Toast.LENGTH_SHORT).show();
try {
jsonObject = new JSONObject(response);
jsonArray = jsonObject.getJSONArray("results");
int i = 0;
while(i < jsonArray.length()) {
JSONObject movie = jsonArray.getJSONObject(i);
Film movieInstance = new Film(movie.getString("original_title"), movie.getString("overview"), "https://image.tmdb.org/t/p/w500" + movie.getString("backdrop_path"));
listFilm.add(movieInstance);
i ++ ;
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
Toast.makeText(getApplicationContext(), "NE RADI", Toast.LENGTH_SHORT).show();
}
});
}
其余两种情况相同。我多次记录所有内容，数据有效，一切都很好，列表中填满了 API 对应的 20 部电影。那么有什么想法吗？总而言之，在第一种情况下，我的应用程序运行良好，而在后一种情况下，没有显示任何数据。任何人都知道或有类似的问题？先感谢您。
您必须让适配器知道您更改了数据。它将通知附属的回收商并更新其观点。
在从 api 添加项目的循环之后，添加：
adapter.notifyDataSetChanged();
在第一个示例中，您不需要它，因为在回收器进行初始布局时（在 onCreate 之后），内容已经存在。