从 TabHost 填充 Listview 片段

Question

这里完全是菜鸟，请多多包涵。我有一个 activity 从我的服务器加载数据并将其显示在列表视图中。现在我需要能够根据 TabHost 重新排序该列表。我正在使用 MaterialTabHost (https://github.com/neokree/MaterialTabs)

这是我用来填充列表视图的代码：

    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();
    // Creating volley request obj
    final Double finalLat = lat;
    final Double finalLon = lon;
    final Double finalLat1 = lat;
    final Double finalLon1 = lon;
    JsonArrayRequest movieReq = new JsonArrayRequest(url,
            new Response.Listener<JSONArray>() {
                @Override
                public void onResponse(final JSONArray response) {
                    Log.d(TAG, response.toString());
                    hidePDialog();

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

                            JSONObject obj = response.getJSONObject(i);
                            viewer movie = new viewer();
                            LatLng point1 = new LatLng(obj.getDouble("lat"), obj.getDouble("long"));
                            LatLng point2 = new LatLng(finalLat, finalLon);
                            distanceInMiles = LatLngTool.distance(point1, point2, LengthUnit.MILE);
                            movie.setTitle(obj.getString("first_name"));
                            movie.setThumbnailUrl(obj.getString("pic"));
                            //movie.setRating(((String) obj.getString("experience")));
                            movie.setYear(Double.parseDouble(String.format("%.2f", distanceInMiles)));

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

                    }

                    // notifying list adapter about data changes
                    // so that it renders the list view with updated data
                    adapter.notifyDataSetChanged();

                    listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
                        @Override
                        public void onItemClick(AdapterView<?> parent, View view,
                                                int position, long id) {
                            String clicked_at = null;
                            try {
                                clicked_at = response.getString(position);
                            } catch (JSONException e) {
                                e.printStackTrace();
                            }
                            Intent i = new Intent(getApplicationContext(), full_view_walker.class);
                            i.putExtra("data", clicked_at);
                            i.putExtra("lat", finalLat1);
                            i.putExtra("lon", finalLon1);
                            i.putExtra("sender_id", sender_id);
                            startActivity(i);

                        }
                    });

                }
            }, 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);
}

现在我的标签内容：

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.user_listview);
    tabHost = (MaterialTabHost) this.findViewById(R.id.tabHost);
    pager = (ViewPager) this.findViewById(R.id.pager);

    // init view pager
    adapter_page = new ViewPagerAdapter(getSupportFragmentManager());
    pager.setAdapter(adapter_page);
    pager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
        @Override
        public void onPageSelected(int position) {
            // when user do a swipe the selected tab change
            tabHost.setSelectedNavigationItem(position);

        }
    });

    // insert all tabs from pagerAdapter data
    for (int i = 0; i < adapter_page.getCount(); i++) {
        tabHost.addTab(
                tabHost.newTab()
                        .setText(adapter_page.getPageTitle(i))
                        .setTabListener(this)
        );

    }    
@Override
public void onTabSelected(MaterialTab tab) {
    pager.setCurrentItem(tab.getPosition()); }

private class ViewPagerAdapter extends FragmentStatePagerAdapter {

    public ViewPagerAdapter(FragmentManager fm) {
        super(fm);

    }

    public Fragment getItem(int num) {
        return new FragmentText();
    }

    @Override
    public int getCount() {
        return 3;
    }
    private String[] lst = {"Distance", "Experience", "History"};
    @Override
    public CharSequence getPageTitle(int position) {
        return lst[position];
    }

}

我这里有 FragmentText：

public class FragmentText extends Fragment{

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

       return inflater.inflate(R.layout.front_list, container, false);
    }
}

现在我真的需要两件事：

1) 如何将 FragmentText 中的 inflater.inflate 连接到加载列表并填充它的代码？ 2) 如何确保它不必在每次用户切换选项卡时都重新加载，并且列表是 loaded/sorted 一次然后从那里重新加载？

编辑：我在 FragmentText 中试过这个：

public class FragmentText extends Fragment{
// Log tag
private static final String TAG = AvailableList.class.getSimpleName();
String sender_id;
double distanceInMiles;
Double lat = null;
Double lon = null;
private ProgressDialog pDialog;
private List<viewer> movieList = new ArrayList<viewer>();
private ListView listView;
private CustomListAdapter adapter;
private String[] leftSliderData = {"Logout", "Contact Us"};
@Override
public void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    lon = getArguments().getDouble("lon");
    lat = getArguments().getDouble("lat");

}
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
   View V = inflater.inflate(R.layout.front_list, container, false);
   listView = (ListView) V.findViewById(R.id.list);
   adapter = new CustomListAdapter(getActivity(), movieList);
   Log.d("Adapter", adapter.toString()+"");
   listView.setAdapter(adapter);
   final Double finalLat = lat;
   final Double finalLon = lon;
   final Double finalLat1 = lat;
   final Double finalLon1 = lon;
   JsonArrayRequest movieReq = new JsonArrayRequest(url,
           new Response.Listener<JSONArray>() {
               @Override
               public void onResponse(final JSONArray response) {
                   Log.d(TAG, response.toString());
                   //hidePDialog();
                   for (int i = 0; i < response.length(); i++) {
                       try {

                           JSONObject obj = response.getJSONObject(i);
                           viewer movie = new viewer();
                           LatLng point1 = new LatLng(obj.getDouble("lat"), obj.getDouble("long"));
                           LatLng point2 = new LatLng(finalLat, finalLon);
                           distanceInMiles = LatLngTool.distance(point1, point2, LengthUnit.MILE);
                           movie.setTitle(obj.getString("first_name"));
                           movie.setThumbnailUrl(obj.getString("pic"));
                           movie.setYear(Double.parseDouble(String.format("%.2f", distanceInMiles)));
                       } catch (JSONException e) {
                           e.printStackTrace();
                       }

                   }

                   // notifying list adapter about data changes
                   // so that it renders the list view with updated data
                   adapter.notifyDataSetChanged();

                   listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
                       @Override
                       public void onItemClick(AdapterView<?> parent, View view,
                                               int position, long id) {
                           String clicked_at = null;
                           try {
                               clicked_at = response.getString(position);
                           } catch (JSONException e) {
                               e.printStackTrace();
                           }
                           Intent i = new Intent(getActivity(), full_view_walker.class);
                           i.putExtra("data", clicked_at);
                           i.putExtra("lat", finalLat1);
                           i.putExtra("lon", finalLon1);
                           i.putExtra("sender_id", sender_id);
                           startActivity(i);

                       }
                   });

               }
           }, 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 V;
}

当我点击一个标签时，这正在加载页面，但它们没有显示！不过，我可以看到正在加载列表的 activity！

Answer 1

1) How to connect the inflater.inflate in FragmentText to the code that loads the list and populates it?

除了您发布的内容之外，没有其他特别之处，但应该有效。

This is loading the pages when I hit a tab, but they aren't showing!

第一个选项卡显示数据吗？

您使用 ViewPager 3 个包含相同片段的页面，因此所有页面的布局都相同。在许多这种情况下，ViewPager 具有与页面内容相同的片段，您描述的行为的发生是因为用户直接在 activity 布局中使用 findViewById() 查找各种页面的小部件。 findViewById() 将 return 该视图在布局中的第一次出现，因此您将始终从第一页获得视图，而除第 0 页之外的任何其他页面将不显示任何内容，尽管数据已加载（并设置在第一页的小部件，未显示）。但是，在最后一个代码片段中，您在膨胀布局中寻找 ListView，所以这不是问题（在第一个代码片段中，您使用简单的 findViewById() 寻找 ListView，不清楚？）所以您可能想看看您的布局并检查它们是否存在问题。

另一个问题是所有的 FragmentText 是否加载相同的数据（"url" 相同？）。如果是，那么您不应该在每个片段中进行该网络调用（浪费），而是您应该有一个点进行网络调用和使用该单点的片段（一个好的选择是 no UI setRetainInstance() 设置为 true 的片段）。

How to make sure it doesn't have to reload each time the user switches tabs, and that the list is loaded/sorted once and then will just reload from there?

同上题。这 3 个 FragmentText 中的每个数据列表是否相同？如果是，那么这些选项卡只是根据某些标准（距离、经验等）对数据进行排序，而不是使用单个数据列表并将标识符传递给 FragmentText 以了解应该在那里进行什么排序。然后，当片段变为可见时（检查 setUserVisibleHint()），根据该页面的标准对单个数据列表进行排序并将其显示给用户。

从 TabHost 填充 Listview 片段

Populating Listview fragment from TabHost

android

android-fragments

android-listview