使用 Retrofit 2 填充 ListView

Question

我正在尝试使用来自服务器的 JSON 填充 ListView。我正在从服务器获取数据，但我似乎无法弄清楚如何将它放入 ListView 中。我得到的错误是在 onResponse 中。

它说：“错误：（84、54）错误：class JucatoriLiberiArrayAdapter 中的构造函数 JucatoriLiberiArrayAdapter 不能应用于给定类型；必需：上下文，ArrayList 发现：FragmentActivity,Call> 原因：实参Call>无法通过方法调用转换为ArrayList

我想我已经尝试了几乎所有的 Alt+Enter 修复方法。还尝试将类型从 Call<ArrayList<FreePlayers> 更改为仅 ArrayList<> 或仅 Call<>.

这是我的 class:

   @Override
        public void onActivityCreated(final Bundle savedInstanceState) {
            super.onActivityCreated(savedInstanceState);


            HttpLoggingInterceptor interceptor = new HttpLoggingInterceptor();
            interceptor.setLevel(HttpLoggingInterceptor.Level.BODY);
            OkHttpClient client = new OkHttpClient.Builder().addInterceptor(interceptor).build();

            final Retrofit builder = new Retrofit.Builder()
                    .addConverterFactory(GsonConverterFactory.create())
                    .client(client)
                    .baseUrl(ROOT)
                    .build();

            REST_CLIENT = builder.create(API.class);


            final Call<FreePlayers> request = REST_CLIENT.getFreePlayers(1);
            request.enqueue(new Callback<FreePlayers>() {
                @Override
                public void onResponse(final Call<FreePlayers> call, final Response<FreePlayers> response) {
                    ArrayList<FreePlayers> players = null;

                    players = call;

                    ListView lv = (ListView) getView().findViewById(android.R.id.list);

                    JucatoriLiberiArrayAdapter adapter = new JucatoriLiberiArrayAdapter(getActivity(),
                            players);

                    lv.setAdapter(adapter);


                }

                @Override
                public void onFailure(final Call<FreePlayers> call, final Throwable t) {

                }
            });


        }

我的API界面：

public interface API {

    @FormUrlEncoded
    @POST("/fan-sport/app-test/")
    Call<ArrayList<FreePlayers>> getFreePlayers(@Field("getFreePlayers") int freePlayers);

}

这是我的自定义适配器：

public class JucatoriLiberiArrayAdapter extends BaseAdapter {

    private Context context;
    private ArrayList<FreePlayers> players;




    public JucatoriLiberiArrayAdapter(Context context, ArrayList<FreePlayers> playersList) {
        super();

        this.context = context;
        this.players = playersList;
    }

    @Override
    public int getCount() {
        return 0;
    }

    @Override
    public Object getItem(final int position) {
        return null;
    }

    @Override
    public long getItemId(final int position) {
        return 0;
    }

    @Override
    public View getView(final int position, View convertView, final ViewGroup parent) {



        LayoutInflater inflater = (LayoutInflater) this.context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);

        if (convertView == null) {

            convertView = inflater.inflate(R.layout.list_view_jucatori_liberi, null);


            TextView playerName = (TextView) convertView.findViewById(R.id.name);
            playerName.setText((CharSequence) players.get(position));


        }


        return convertView;

    }


}

Answer 1

在您的 onResponse() 中，您收到一个 Call 对象，而您的适配器需要一个 List<FreePlayers>，响应参数是您要提供给适配器的播放器列表。

试试这个代码：

final Call<List<FreePlayers>> request = REST_CLIENT.getFreePlayers(1);

request.enqueue(new Callback<List<FreePlayers>>() {

    @Override
    public void onResponse(final Call<List<FreePlayers>> call, final Response<List<FreePlayers>> response) {

        ArrayList<FreePlayers> players = null;

        players = response.body();

        ListView lv = (ListView) getView().findViewById(android.R.id.list);

        JucatoriLiberiArrayAdapter adapter = new JucatoriLiberiArrayAdapter(getActivity(),
                        players);

        lv.setAdapter(adapter);


    }

    @Override
    public void onFailure(final Call<FreePlayers> call, final Throwable t) {

    }
});

Answer 2

呼叫已分配给玩家，但玩家类型为 ArrayList<FreePlayers>，呼叫类型为 Call<List<FreePlayers>。不一样。适配器需要 ArrayList<FreePlayers>.

Answer 3

您要声明

Call<FreePlayers>,

但希望收到

Call<ArrayList<FreePlayers>>.

另外，您的适配器坏了。这些方法应该类似于：

@Override
public int getCount() {
    if (players == null) return 0;
    return players.size();
}

@Override
public Object getItem(final int position) {
    if (players == null || players.size() == 0) return null; 
    return players.get(position);
}

@Override
public long getItemId(final int position) {
    return getItem(position).getId(); // or something like an id that suits you.
}

使用 Retrofit 2 填充 ListView

Populate ListView using Retrofit 2

android

retrofit2