Question

我试图从我的MainActivity显示我的列表碎片。我跟着这个https://www.journaldev.com/10416/android-listview-with-custom-adapter-example-tutorial#android-listview-custom-adapter-overview。这就是

   public boolean onNavigationItemSelected(MenuItem item) {
        // Handle navigation view item clicks here.
        int id = item.getItemId();
        FragmentManager fm = getSupportFragmentManager();
        ListFragment fragment = null;
        String title = getString(R.string.app_name);
        FragmentTransaction ft = getSupportFragmentManager().beginTransaction();

        if (id == R.id.nav_rijek) {
            fragment = new Rijek();
            title  = "Rijek Item from DO";

        } else if (id == R.id.nav_share) {

        } else if (id == R.id.nav_logout) {

            Logoutdialog dialogFragment = new Logoutdialog();
            dialogFragment.setRetainInstance(true);
            dialogFragment.show( this .getFragmentManager(), "Tag");
        }

        if (fragment != null) {
            ft.replace(R.id.content_frame, fragment);
            ft.commit();
        }

        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        drawer.closeDrawer(GravityCompat.START);

        if (getSupportActionBar() != null) {
            getSupportActionBar().setTitle(title);
        }

        return true;
    }

这是我的activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/drawer_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:openDrawer="start">

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/content_frame"/>
    <include
        layout="@layout/app_bar_main"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

    <android.support.design.widget.NavigationView
        android:id="@+id/nav_view"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        android:fitsSystemWindows="true"
        app:headerLayout="@layout/nav_header_main"
        app:menu="@menu/activity_main_drawer" />
</android.support.v4.widget.DrawerLayout>

这是我的ListFragment（Rijek.java）

    public class Rijek extends ListFragment {

    ArrayList<RijekModel> dataModels;
    ListView listView;
    private static Rijekadapter adapter;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        Toast toast = Toast.makeText(getActivity(), "Load listfragment",
                Toast.LENGTH_SHORT);
        toast.show();
        startASycnc();
        View v = inflater.inflate(R.layout.rijekmain, container, false);
        listView = (ListView) v.findViewById (android.R.id.list);
        return v;
    }

    public void startASycnc() {
        SessionHandler ses = new SessionHandler();
        String Nip = new SessionHandler().getNip(getContext());
        new getListRijek().execute(Nip);
    }

    public class getListRijek extends AsyncTask<String,String,String>{

        HttpURLConnection conn;
        URL url = null;
        String result = "";

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
        }

        @Override
        protected String doInBackground(String... params) {
            try {
                url = new URL("http://192.168.3.223:84/storelf/api/Getrijek");
            } catch (MalformedURLException e) {
                e.printStackTrace();
            }
            try {

                conn = (HttpURLConnection)url.openConnection();
                conn.setConnectTimeout(100);
                conn.setRequestMethod("POST");

                conn.setDoInput(true);
                conn.setDoOutput(true);

                Uri.Builder builder = new Uri.Builder()
                        .appendQueryParameter("user_login", params[0]);
                String query = builder.build().getEncodedQuery();

                OutputStream os = conn.getOutputStream();
                BufferedWriter writer = new BufferedWriter(
                        new OutputStreamWriter(os, "UTF-8"));
                writer.write(query);
                writer.flush();
                writer.close();
                os.close();
                conn.connect();
            } catch (IOException e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
                return "exception";
            }
            try {
                int response_code = conn.getResponseCode();
                if (response_code == HttpURLConnection.HTTP_OK) {
                    InputStream input = conn.getInputStream();
                    BufferedReader reader = new BufferedReader(new InputStreamReader(input));
                    String line = null;
                    while ((line = reader.readLine()) != null) {
                        result += line;
                    }

                    try {

                        JSONArray jsonArray = new JSONArray(result);
                        dataModels= new ArrayList<>();
                        for (int i = 0; i < jsonArray.length(); i++) {
                                JSONObject c = jsonArray.getJSONObject(i);
                                String DrDocumentNo = c.getString("DrDocumentNo");
                                String DoDocumentNo = c.getString("DoDocumentNo");
                                String RijekCode = c.getString("RijekCode");
                                 dataModels.add(new RijekModel(RijekCode,DrDocumentNo, DoDocumentNo));
                            }
                        adapter= new Rijekadapter(dataModels,getContext());
                        }

                    catch (JSONException e) {
                        e.printStackTrace();
                    }
                } else {
                  Log.e("ERROR", "ERR --> " +response_code);
                }

            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                conn.disconnect();
            }
            return null;
        }

        @Override
        protected void onPostExecute(String s) {
            super.onPostExecute(s);
        }

    }

}

这是我的rijekmain.xml

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

    <Button
        android:id="@+id/button"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Button" />

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

</LinearLayout>

没有错误。但是当我运行它时，我的列表视图并没有显示出来。我该如何解决？提前谢谢，对不起我的英文

Answer 1

您没有为ListView设置适配器。当数据可用时，您必须创建/更新适配器并将其设置为ListView。在onPostExecute()方法内将适配器设置为ListView

ListFragment使用：

setListAdapter(adapter);

在ListFragment访问ListView，您可以调用

getListView();

Answer 2

试试这个

    listView = (ListView) v.findViewById (android.R.id.list);

    Insted of

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

Answer 3

您正在后台线程中更新 UI元素（列表视图） ..执行setAdapter中的onPostExecute(...)部分。在后台线程中获取json 从doInBackgroud()返回结果 ..解析JSON对象并更新onPostExecute()中的适配器

ListFragment没有显示

3 个答案: