用凌空填充片段中的 JSON 列表视图答案

【问题标题】：Populating JSON listview in a fragment with volley用凌空填充片段中的 JSON 列表视图
【发布时间】：2015-06-28 03:03:33
【问题描述】：

我是 java/android 编程的绿角，但我试图添加不同的教程来创建一个自定义应用程序，这将是一个很酷的实验，这对这里的大多数人来说可能很容易，但我被困在了这个一个，我正在尝试使用此Navigation Drawer View Pager 尝试使用此Custom ListView with Volley.from android hive "great tutorials btw" 填充选项卡一个片段。

我想将自定义列表视图的 MainActivity.java 中的代码与 volley 传输到导航抽屉中的 HomeFragment.java 中，但出现错误。

主要活动

public class MainActivity extends Activity {
  // Log tag
   private static final String TAG = MainActivity.class.getSimpleName();

// Movies json url
private static final String url = "http://api.androidhive.info/json/movies.json";
private ProgressDialog pDialog;
private List<Movie> movieList = new ArrayList<Movie>();
private ListView listView;
private CustomListAdapter adapter;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    listView = (ListView) findViewById(R.id.list);
    adapter = new CustomListAdapter(this, movieList);
    listView.setAdapter(adapter);

    pDialog = new ProgressDialog(this);
    // Showing progress dialog before making http request
    pDialog.setMessage("Loading...");
    pDialog.show();

    // changing action bar color
    getActionBar().setBackgroundDrawable(
            new ColorDrawable(Color.parseColor("#1b1b1b")));

    // Creating volley request obj
    JsonArrayRequest movieReq = new JsonArrayRequest(url,
            new Response.Listener<JSONArray>() {
                @Override
                public void onResponse(JSONArray response) {
                    Log.d(TAG, response.toString());
                    hidePDialog();

                    // Parsing json
                    for (int i = 0; i < response.length(); i++) {
                        try {

                            JSONObject obj = response.getJSONObject(i);
                            Movie movie = new Movie();
                            movie.setTitle(obj.getString("title"));
                            movie.setThumbnailUrl(obj.getString("image"));
                            movie.setRating(((Number) obj.get("rating"))
                                    .doubleValue());
                            movie.setYear(obj.getInt("releaseYear"));

                            // Genre is json array
                            JSONArray genreArry = obj.getJSONArray("genre");
                            ArrayList<String> genre = new ArrayList<String>         ();
                            for (int j = 0; j < genreArry.length(); j++) {
                                genre.add((String) genreArry.get(j));
                            }
                            movie.setGenre(genre);

                            // adding movie to movies array
                            movieList.add(movie);

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

                      }

                    // notifying list adapter about data changes
                    // so that it renders the list view with updated data
                    adapter.notifyDataSetChanged();
                }
            }, new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                    VolleyLog.d(TAG, "Error: " + error.getMessage());
                    hidePDialog();

                }
            });

    // Adding request to request queue
AppController.getInstance().addToRequestQueue(movieReq);
 }

@Override
public void onDestroy() {
    super.onDestroy();
    hidePDialog();
}

private void hidePDialog() {
    if (pDialog != null) {
        pDialog.dismiss();
        pDialog = null;
    }
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

}

HomeFragment

  public class HomeFragment extends Fragment {


    public HomeFragment() {
        // Required empty public constructor
    }

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

    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_home, container, false);
    }
    }

组合代码

    public class HomeFragment extends Fragment{

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

    // Movies json url
    private static final String url = "http://api.androidhive.info/json/movies.json";
    private ProgressDialog pDialog;
    private List<Movie> movieList = new ArrayList<Movie>();
    private ListView listView;
    private CustomListAdapter adapter;
//private TextView txtFragmentone;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
    }

    public static HomeFragment newInstance() {
        HomeFragment fragment = new HomeFragment();
        return fragment;
    }

    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {

        View rootView = inflater.inflate(R.layout.fragment_home, container, false);
        //txtFragmentone = (TextView) rootView.findViewById(R.id.txtFragmentOne);
        //txtFragmentone.setText(R.string.fragment_tab_one);
        rootView.setLayoutParams(new        LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT,  LinearLayout.LayoutParams.MATCH_PARENT ));

        listView = (ListView) getActivity().findViewById(R.id.list);

        adapter = new CustomListAdapter(this, movieList);
        listView.setAdapter(adapter);

        pDialog = new ProgressDialog(this);
        // Showing progress dialog before making http request
        pDialog.setMessage("Loading...");
        pDialog.show();

        // changing action bar color
        getActivity().getActionBar().setBackgroundDrawable(
                new ColorDrawable(Color.parseColor("#4cbaff")));

        // Creating volley request obj
        JsonArrayRequest movieReq = new JsonArrayRequest(url,
                new Response.Listener<JSONArray>() {
                    @Override
                    public void onResponse(JSONArray response) {
                        Log.d(TAG, response.toString());
                        hidePDialog();

                        // Parsing json
                        for (int i = 0; i < response.length(); i++) {
                            try {

                                JSONObject obj = response.getJSONObject(i);
                                Movie movie = new Movie();
                                movie.setTitle(obj.getString("title"));
                                movie.setThumbnailUrl(obj.getString("image"));
                                movie.setRating(((Number) obj.get("rating"))
                                        .doubleValue());
                                movie.setYear(obj.getInt("releaseYear"));

                                // Genre is json array
                                JSONArray genreArry = obj.getJSONArray("genre");
                                ArrayList<String> genre = new ArrayList<String>();
                                for (int j = 0; j < genreArry.length(); j++) {
                                    genre.add((String) genreArry.get(j));
                                }
                                movie.setGenre(genre);

                                // adding movie to movies array
                                movieList.add(movie);

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

                        }

                        // notifying list adapter about data changes
                        // so that it renders the list view with updated data
                        adapter.notifyDataSetChanged();
                    }
                }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
                VolleyLog.d(TAG, "Error: " + error.getMessage());
                hidePDialog();

            }
        });

        // Adding request to request queue
        AppController.getInstance().addToRequestQueue(movieReq);

        return rootView;
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        hidePDialog();
    }

    private void hidePDialog() {
        if (pDialog != null) {
            pDialog.dismiss();
            pDialog = null;
        }
    }



    }

但是我的错误

rootView.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT,      LayoutParams.MATCH_PARENT ));

AppController.java

  package androidhive.info.materialdesign.app;

   import com.android.volley.Request;
   import com.android.volley.RequestQueue;
   import com.android.volley.toolbox.ImageLoader;
   import com.android.volley.toolbox.Volley;
   import androidhive.info.materialdesign.util.LruBitmapCache;

   import android.app.Application;
   import android.text.TextUtils;

    /**
    * @author fanjavaid
    *
    */
  public class AppController extends Application {
    public static final String TAG = AppController.class.getSimpleName();

    private RequestQueue mRequestQueue;
    private ImageLoader mImageLoader;

    private static AppController mInstance;

    @Override
    public void onCreate() {
        super.onCreate();
        mInstance = this;
    }

    public static synchronized AppController getInstance() {
        return mInstance;
    }

    public RequestQueue getRequestQueue() {
        if (mRequestQueue == null) {
            mRequestQueue = Volley.newRequestQueue(getApplicationContext());
        }

        return mRequestQueue;
    }

    public ImageLoader getImageLoader() {
        getRequestQueue();
        if (mImageLoader == null) {
            mImageLoader = new ImageLoader(this.mRequestQueue,
                    new LruBitmapCache());
        }
        return this.mImageLoader;
    }

    public <T> void addToRequestQueue(Request<T> req, String tag) {
        // set the default tag if tag is empty
        req.setTag(TextUtils.isEmpty(tag) ? TAG : tag);
        getRequestQueue().add(req);
    }

    public <T> void addToRequestQueue(Request<T> req) {
        req.setTag(TAG);
        getRequestQueue().add(req);
    }

    public void cancelPendingRequests(Object tag) {
        if (mRequestQueue != null) {
            mRequestQueue.cancelAll(tag);
        }
    }
  }

fragment_home.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="androidhive.info.materialdesign.activity.HomeFragment">


    <ListView
        android:id="@+id/list"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:divider="@color/list_divider"
        android:dividerHeight="1dp"
        android:listSelector="@drawable/list_row_selector" />

</RelativeLayout>

但是，如果我将 LayoutParams 更改为 Linear.LayoutParams 它会崩溃如果你能帮忙就太好了！！！

【问题讨论】：

作为一个初学者，要同时让所有东西都正常工作是非常困难的。我建议从一件非常简单的事情开始——一个带有显示静态内容的 ListView 的活动。然后让 Volley 代码工作，以您需要的格式检索您需要的数据。然后从 Volley 数据动态填充 ListView，依此类推。这项工作会更容易，如果你遇到困难，你会更容易获得帮助，因为你可以提出一个狭隘的问题，而不是这个拥有大量没人愿意阅读的代码的怪物。
我有同样的问题here，可能有人可以帮助我们！谢谢

标签： java android listview android-fragments android-listview

【解决方案1】：

我也在努力实现同样的目标。我结合了登录和导航抽屉。我还尝试在主页片段中显示静态数据并且它有效。出于调试目的，我将默认片段更改为第二个片段。因此，现在当我打开抽屉并单击主页选项卡时，我再次返回登录屏幕。

【讨论】：