ListView没有显示没有错误的任何内容

I'm using Volley to grab JSON data from a web page to then process said data and add it to a HashMap. After, I create a ListAdapter and feed it the HashMap. All of this works, I get no errors but for some reason nothing actually shows up.

我正在使用Volley从网页中获取JSON数据,然后处理所述数据并将其添加到HashMap。之后,我创建了一个ListAdapter并将其提供给HashMap。所有这一切都有效,我没有错误但由于某种原因没有实际出现。

The ListView is nested in a LinearLayout fragment and the adapter uses a custom layout. The fragment renders fine.

ListView嵌套在LinearLayout片段中,适配器使用自定义布局。片段渲染得很好。

onCreateView in the MainActivity

MainActivity中的onCreateView

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

        View view =  inflater.inflate(R.layout.menu_betriebe, container, false);

        mitgliederList = new ArrayList<>();
        mitgliederListView = view.findViewById(R.id.menu_betriebe_mitglieder_list);

        String url = getString(R.string.api_base_url) + "removed";

        JsonObjectRequest jsonObjReq = new JsonObjectRequest(Request.Method.GET,
                url, null,
                new Response.Listener<JSONObject>() {
                    @Override
                    public void onResponse(JSONObject response) {

                        JSONArray mitglieder;

                        try {
                            mitglieder = response.getJSONArray("data");

                            for (int i = 0; i < mitglieder.length(); i++) {

                                JSONObject mitgliedObject = mitglieder.getJSONObject(i);

                                String mitglied_name = mitgliedObject.getString("mitglied_name");

                                Log.d("WBV", mitglied_name);

                                HashMap<String, String> mitglied = new HashMap<>();
                                mitglied.put("mitglied_name", mitglied_name);

                                mitgliederList.add(mitglied);
                            }

                            ListAdapter adapter = new SimpleAdapter(
                                    getActivity(),
                                    mitgliederList,
                                    R.layout.betriebe_list_item,
                                    new String[]{"mitglied_name"},
                                    new int[]{R.id.betriebe_list_item_mitglied_name});

                            mitgliederListView.setAdapter(adapter);

                        } catch (JSONException e) {

                        }
                    }
                }, new Response.ErrorListener() {
                    @Override
                    public void onErrorResponse(VolleyError error) {
                        VolleyLog.d("WBV", "Error: " + error.getMessage());
                    }
                }
        );

        // Adding request to request queue
        AppController.getInstance().addToRequestQueue(jsonObjReq, "json_obj_req");

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

The fragment

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/menu_betriebe"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <ListView
        android:id="@+id/menu_betriebe_mitglieder_list"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</LinearLayout>

The list item layout

列表项布局

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical">

    <TextView
        android:id="@+id/betriebe_list_item_mitglied_name"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:padding="5dp"
        android:textColor="@color/colorPrimaryDark"
        android:textSize="16sp"
        android:textStyle="bold"
        android:text="HalloTest"/>

</LinearLayout>

1 个解决方案

#1

try the following

尝试以下方法

1. make the oncreateView returns view object only after inflating layout

   使oncreateView仅在膨胀布局后返回视图对象

2. put the http reguest using volley in onViewCreate Method not onCreateView method

   在onViewCreate方法而不是onCreateView方法中使用volley使用http reguest

3. call adapter.notifyDataSetChanged(); if you still have problems

call adapter.notifyDataSetChanged();如果你还有问题