Android ListFragment视图不显示

Question

我有一个 ListFragment class，它应该与 SimpleAdapter 一起显示 listOfMyGroups 数组中包含的组名列表。编译后没有错误，但是没有视图，只有一个空白页面。数据通过改造成功加载到 listOfBookmark 列表，它包括所有加载的名称。

public class MyGroupsFragment extends ListFragment {

private SimpleAdapter simpleAdapter;
private Group group;
private String valueOfNazwa;
private String valueOfId;
private SharedPreferences pref;
private SharedPreferences.Editor editor;
private Bookmark bookmark;
private List<Bookmark> listOfBookmarks;
private List<LinkedHashMap<String, String>> listOfMyGroups;
private List<String[]> helperArrayList;
private ListView listView;

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

    View view = inflater.inflate(R.layout.fragment_groups, container, false);
    listView = (ListView) view.findViewById(android.R.id.list);

    pref = PreferenceManager.getDefaultSharedPreferences(getContext());

    listOfBookmarks = new ArrayList<Bookmark>();
    listOfMyGroups = new ArrayList<LinkedHashMap<String, String>>();
    helperArrayList = new ArrayList<String[]>();

    return view;
}

@Override
public void onViewCreated (View view, Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);

    init();
    bookmarkToString();

    initAdapter();

    listView = getListView();
    listView.setTextFilterEnabled(true);

    listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        public void onItemClick(AdapterView<?> parent, View view,
                                int position, long id) {
            Toast.makeText(getContext(), ((TextView) view).getText(),
                    Toast.LENGTH_SHORT).show();

            for (Map.Entry<String, String> entry : listOfMyGroups.get(position).entrySet())
                valueOfNazwa = entry.getValue();


            for (String[] string : helperArrayList) {
                if (string[1] == valueOfNazwa)
                    valueOfId = string[0];
            }

            System.out.println(valueOfId + " - " + valueOfNazwa);
            group = new Group(valueOfId, valueOfNazwa);

            editor = pref.edit();
            editor.putString(Constants.ID_GROUP, valueOfId);
            editor.putString(Constants.NAZWA, valueOfNazwa);
            editor.apply();

            startActivity(new Intent(getContext(), MainActivity.class));
        }
    });

}

private void initAdapter(){
    simpleAdapter = new SimpleAdapter(getContext(), listOfMyGroups,
            android.R.layout.simple_list_item_1,
            new String[] { "groups" }, new int[] { android.R.id.text1 });
    listView.setAdapter(simpleAdapter);
}

public void init() {
    OkHttpClient.Builder okHttpClient = new OkHttpClient.Builder();

    HttpLoggingInterceptor debugger =
            new HttpLoggingInterceptor()
                    .setLevel(HttpLoggingInterceptor.Level.BODY);
    okHttpClient
            .addInterceptor(debugger);

    Retrofit retrofit = new Retrofit.Builder()
            .baseUrl(Constants.BASE_URL)
            .addConverterFactory(GsonConverterFactory.create())
            .client(okHttpClient.build())
            .build();

    RequestInterface requestInterface = retrofit.create(RequestInterface.class);

    String email = pref.getString(Constants.EMAIL, "");
    System.out.println(email);
    String id_group = pref.getString(Constants.ID_GROUP, "");
    System.out.println(id_group);
    String nazwa = pref.getString(Constants.NAZWA, "");

    Integer id_int_group = Integer.parseInt(id_group);
    Bookmark bookmark = new Bookmark(email, id_int_group, nazwa);

    ServerRequest request2 = new ServerRequest();
    request2.setOperation(Constants.GET_MY_GROUPS);
    request2.setBookmark(bookmark);

    Call<List<Bookmark>> response2 = requestInterface.operation2(request2);

    response2.enqueue(new Callback<List<Bookmark>>() {

        @Override
        public void onResponse(Call<List<Bookmark>> call, retrofit2.Response<List<Bookmark>> response2) {
            listOfBookmarks = response2.body();
        }

        @Override
        public void onFailure(Call<List<Bookmark>> call, Throwable t) {

            Log.d(Constants.TAG, "Nie zaladowano!", t);

        }
    });
}

public void bookmarkToString() {
    for(Bookmark bookmark : listOfBookmarks) {
        String nazwa = bookmark.getNazwa();
        listOfMyGroups.add(createGroup("groups", nazwa));
    }
}

private LinkedHashMap<String, String> createGroup(String name, String number) {
    LinkedHashMap<String, String> helperGroupList = new LinkedHashMap<String, String>();
    helperGroupList.put(name, number);
    return helperGroupList;
}
}

我的fragment_groups.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:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin">

<ListView
    android:id="@android:id/list"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_alignParentTop="true"
    android:layout_centerHorizontal="true"
    android:layout_marginTop="50dp" >
</ListView>

Answer 1

如果你的代码没有其他问题，我认为的解决方案是：

问题

您的 bookmarkToString 函数在加载 listOfBookmarks 后未被调用。

你的 init(http request via retrofit) 函数和 listOfBookmarks 函数在 onCreateView.

中同时被调用

解决方案

response2.enqueue(new Callback<List<Bookmark>>() {

    @Override
    public void onResponse(Call<List<Bookmark>> call, retrofit2.Response<List<Bookmark>> response2) {
        listOfBookmarks = response2.body();
        bookmarkToString(); 
        simpleAdapter.notifyDataSetChanged(); // refresh listivew
    }

    @Override
    public void onFailure(Call<List<Bookmark>> call, Throwable t) {

        Log.d(Constants.TAG, "Nie zaladowano!", t);

    }
});

Android ListFragment视图不显示

Android ListFragment view not display

android

retrofit2

android-listfragment