java - CustomListView未填充在Android的Fragment中

Question

在 fragment (称为VideoCallFragment)启动时，第一个操作是向服务器(Ruby)请求数据并收集数据并填充到 ListView 。为了查看它是否完成，我制作了一个进度对话框和onPostExcute，我使用responseView.textSet(response)。然而，加载完成后数据并未填充。

但是，如果我在相同的布局中创建一个 EditText View (空的)，并且如果我单击该 View (尽管我没有将此 EditText View 设为能够在此之后进行处理)，则数据将被填充。但很明显，用户不会喜欢这个不必要的过程。这是由 VideoCallFragment 中 AsnyTask 和 rootView 初始化之间的延迟引起的吗？我为这种情况编写了代码。

并且对适配器(listview)也持怀疑态度，我

final ListView lv=(ListView) rootView.findViewById(R.id.listView_classroom);
CustomAdapter adapter = new CustomAdapter(getActivity(), prgmNameList, dateList, caseList);
lv.setAdapter(adapter);
adapter.notifyDatasetChanged();

其中 prgmNameList、dateList、caseList 都是我在 VideoCallFrament 类中作为变量创建的 ArrayList。

但是最后一行不起作用并显示“无法解析方法notifyDatasetChanged();所以我在这里迷失了:(

CustomAdapter 看起来像这样。

public class CustomAdapter extends BaseAdapter{

    ArrayList classroom_name_result;
    ArrayList date_result;
    ArrayList case_result;
    String [] tutor_result;

    Context context;
    int [] imageId;
    private static LayoutInflater inflater=null;

    public CustomAdapter(Activity mainActivity, ArrayList prgmNameList, ArrayList datelist, ArrayList caselist /*, int[] prgmImages*/) {
        // TODO Auto-generated constructor stub

        classroom_name_result= prgmNameList;
        date_result = datelist;
        case_result = caselist;
        context=mainActivity;
        inflater = ( LayoutInflater )context.
                getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }

    @Override
    public int getCount() {
        // TODO Auto-generated method stub
        return classroom_name_result.size();
    }

    @Override
    public Object getItem(int position) {
        // TODO Auto-generated method stub
        return position;
    }

    @Override
    public long getItemId(int position) {
        // TODO Auto-generated method stub
        return position;
    }

    public class Holder
    {
        TextView tv;
        TextView date;
        TextView mcase;
        ImageView img;

    }
    @Override
    public View getView(final int position, View convertView, ViewGroup parent) {
        // TODO Auto-generated method stub
        Holder holder=new Holder();
        View rowView;
        rowView = inflater.inflate(R.layout.program_list, null);

        holder.tv=(TextView) rowView.findViewById(R.id.lesson);
        holder.tv.setText(classroom_name_result.get(position).toString());

        holder.date=(TextView) rowView.findViewById(R.id.date);
        holder.date.setText(date_result.get(position).toString());

        holder.mcase=(TextView) rowView.findViewById(R.id.course);
        holder.mcase.setText(case_result.get(position).toString());
        return rowView;
    }

}

下面第一个是具有 fragment 的 MainActivity。名为 VideoCallFragment 的 fragment 是未正确填充的类。

public class MainActivity extends ActionBarActivity
        implements NavigationDrawerFragment.NavigationDrawerCallbacks {

    some variables...

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.mainactivity2);

        mNavigationDrawerFragment = (NavigationDrawerFragment)
                getSupportFragmentManager().findFragmentById(R.id.navigation_drawer);
        mTitle = getTitle();
        mNavigationDrawerFragment.setUp(
                R.id.navigation_drawer,
                (DrawerLayout) findViewById(R.id.drawer_layout));
    }

    @Override
    public void onNavigationDrawerItemSelected(int position) {
        // update the main content by replacing fragments
        FragmentManager fragmentManager = getSupportFragmentManager();
        Fragment fragmentToLaunch = getFragmentToLaunch(position);
        fragmentManager.beginTransaction()
                .replace(R.id.container, fragmentToLaunch)
                .commit();
    }

    public void onSectionAttached(int number) {
        switch (number) {
            case CASE_SECTION_EDIT_PROFILE:
                mTitle = getString(R.string.title_section1);
                break;
            case CASE_SECTION_VIDEO_CALL:
                mTitle = getString(R.string.title_section2);
                break;
            default:
                break;
        }
    }

    public void restoreActionBar() {
        ActionBar actionBar = getSupportActionBar();
        actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_STANDARD);
        actionBar.setDisplayShowTitleEnabled(true);
        actionBar.setTitle(mTitle);
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        if (!mNavigationDrawerFragment.isDrawerOpen()) {
            // Only show items in the action bar relevant to this screen
            // if the drawer is not showing. Otherwise, let the drawer
            // decide what to show in the action bar.
            getMenuInflater().inflate(R.menu.main, menu);
            restoreActionBar();
            return true;
        }
        return super.onCreateOptionsMenu(menu);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        int id = item.getItemId();

        if (id == R.id.action_build_info) {
            String versionInfo = "SDK Version: " + sg.com.temasys.skylink.sdk.BuildConfig.VERSION_NAME
                    + "\n" + "Sample application version: " + BuildConfig.VERSION_NAME;
            Log.d(TAG, versionInfo);
            Toast.makeText(this, versionInfo, Toast.LENGTH_LONG).show();
            return true;
        }

        return super.onOptionsItemSelected(item);
    }


    public Fragment getFragmentToLaunch(int position) {
        Fragment fragmentToLaunch = null;
        switch (position) {
            case CASE_FRAGMENT_EDIT_PROFILE:
                fragmentToLaunch = new EditProfileFragment();
                break;
            case CASE_FRAGMENT_VIDEO_CALL:
                fragmentToLaunch = new VideoCallFragment();
                break;

            default:
                break;
        }

        Bundle args = new Bundle();
        args.putInt(ARG_SECTION_NUMBER, position + 1);
        fragmentToLaunch.setArguments(args);

        return fragmentToLaunch;
    }
}

视频通话 fragment

public class VideoCallFragment extends Fragment implements LifeCycleListener, MediaListener, RemotePeerListener {
    some varaibles.....

    private ArrayList<String> prgmNameList = new ArrayList<String>();
    private ArrayList<String> caseList = new ArrayList<String>();
    private ArrayList<String> dateList = new ArrayList<String>();

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

        View rootView = inflater.inflate(R.layout.fragment_video_call, container, false);
        parentFragment = (LinearLayout) rootView.findViewById(R.id.ll_video_call);

        etRoomName = (EditText) rootView.findViewById(R.id.et_room_name);
        etRoomName.setVisibility(View.GONE);

        responseView = (TextView) rootView.findViewById(R.id.responseView);

        SharedPreferences settings = PreferenceManager
                .getDefaultSharedPreferences(getContext());
        String auth_token_string = settings.getString("token", ""/*default value*/);

        final ListView lv=(ListView) rootView.findViewById(R.id.listView_classroom);

        CustomAdapter adapter = new CustomAdapter(getActivity(), prgmNameList, dateList, caseList);
        lv.setAdapter(adapter);


        lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

                String classroom = ((TextView) view.findViewById(R.id.lesson)).getText().toString();
                Toast.makeText(getActivity(), classroom, Toast.LENGTH_SHORT).show();
                lv.setVisibility(View.GONE);
                classroom_enter(classroom);
            }
        });
        new soonClass().execute(auth_token_string);
        return rootView;
    }


    class soonClass extends AsyncTask<String, String, String> {
        ProgressDialog pd;
        private Exception exception;
        protected void onPreExecute() {

            pd = new ProgressDialog(getActivity());
            pd.setMessage("Logining..");
            pd.show();

        }

        protected String doInBackground(String... args) {


            String auth_token_string = args[0];

            try {
                URL url = new URL("url");
                HttpURLConnection connection = (HttpURLConnection) url.openConnection();
                /* token call */
                String urlParameters = "token=" + auth_token_string ;

                connection.setRequestMethod("POST");
                connection.setDoOutput(true);
                DataOutputStream dStream = new DataOutputStream(connection.getOutputStream());

                dStream.writeBytes(urlParameters);
                dStream.flush();
                dStream.close();

                InputStream in = connection.getInputStream();

                BufferedReader reader = new BufferedReader(new InputStreamReader(in,"iso-8859-1"),8);
                StringBuffer buffer = new StringBuffer();

                String line = "";
                while ((line = reader.readLine()) != null) {
                    buffer.append(line).append("\n");
                }
                reader.close();
                connection.disconnect();
                JSONObject jsonObj = null;

                jsonObj = new JSONObject(buffer.toString().trim());

                /* status:ok, lessons: xxxx <-- there are two object arrays. */

                JSONArray classes = null;
                classes = jsonObj.getJSONArray("lessons");

                // looping through All Contacts
                for (int i = 0; i < classes.length(); i++) {
                    JSONObject c = classes.getJSONObject(i);

                    prgmNameList.add("lesson_" + c.getString("id"));
                    caseList.add(c.getString("course"));
                    dateList.add(c.getString("date"));
                }
                return "Load Complete";
            }
            catch(Exception e) {
                Log.e("ERROR", e.getMessage(), e);
                return null;
            }
        }

        protected void onPostExecute(String response) {

            if(response == null) {
                response = "THERE WAS AN ERROR";
            }
            //progressBar.setVisibility(View.GONE);
            Log.i("INFO", response);
            if (pd != null) {
                pd.dismiss();
            }
            responseView.setText(response);
        }
    }


    public void classroom_enter(String room_name) {
        somefunction();
    }


    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        getActivity().setVolumeControlStream(AudioManager.STREAM_VOICE_CALL);
    }


    @Override
    public void onResume() {
        super.onResume();
        SharedPreferences settings = PreferenceManager
                .getDefaultSharedPreferences(getContext());
        String auth_token_string = settings.getString("token", ""/*default value*/);
        this.onCreate(null);
    }


    @Override
    public void onDetach() {
        //close the connection when the fragment is detached, so the streams are not open.
        super.onDetach();
        if (skylinkConnection != null && connected) {
            skylinkConnection.disconnectFromRoom();
            skylinkConnection.setLifeCycleListener(null);
            skylinkConnection.setMediaListener(null);
            skylinkConnection.setRemotePeerListener(null);
            connected = false;
            audioRouter.stopAudioRouting(getActivity().getApplicationContext());
        }
        this.onCreate(null);
    }
}

VideoCallFragment 的 XML 布局

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

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/ll_self_video"
        android:orientation="horizontal"
        >

        <EditText
            android:id="@+id/et_room_name"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:hint="Click to Reload"
            android:textAppearance="?android:attr/textAppearanceMedium"/>

        <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/mute_audio"
            android:id="@+id/toggle_audio"
            android:layout_weight="1"
            android:visibility="gone"
            />

        <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/mute_video"
            android:id="@+id/toggle_video"
            android:layout_weight="1"
            android:visibility="gone"
            />

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="New Text"
            android:id="@+id/responseView" />

    </LinearLayout>

    <ListView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/listView_classroom"
        android:layout_gravity="center_horizontal" />


</LinearLayout>

mainactivity 的 XML 布局

<!-- A DrawerLayout is intended to be used as the top-level content view using match_parent for both width and height to consume the full space available. -->
<android.support.v4.widget.DrawerLayout
    android:id="@+id/drawer_layout"
    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"
    tools:context=".MainActivity">

    <!-- As the main content view, the view below consumes the entire
         space available using match_parent in both dimensions. -->
    <FrameLayout
        android:id="@+id/container"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

    <!-- android:layout_gravity="start" tells DrawerLayout to treat
         this as a sliding drawer on the left side for left-to-right
         languages and on the right side for right-to-left languages.
         If you're not building against API 17 or higher, use
         android:layout_gravity="left" instead. -->
    <!-- The drawer is given a fixed width in dp and extends the full height of
         the container. -->


    <fragment
        android:id="@+id/navigation_drawer"
        android:name="com.example.sungpah.sungpahfirst.NavigationDrawerFragment"
        android:layout_width="@dimen/navigation_drawer_width"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        tools:layout="@layout/fragment_navigation_drawer"/>

</android.support.v4.widget.DrawerLayout>

我尝试提供尽可能详细的信息，以便其他人在答案发布后可以轻松查看和引用!请帮助我!!

Answer 1

However the final line didn't work and says "Cannot resolve method notifyDatasetChanged();

这是因为方法签名是带有大写 S 的 notifyDataSetChanged()。

However the data was not populated after loading is done.

这是因为适配器(以及 ListView)不知道其数据已更新。

• 为您的 VideoCallFragment 提供对适配器的引用:

  private CustomAdapter adapter;
  

• 设置此适配器引用

          final ListView lv=(ListView) rootView.findViewById(R.id.listView_classroom);
  
          adapter = new CustomAdapter(getActivity(), prgmNameList, dateList, caseList);
          lv.setAdapter(adapter);
  

• 加载所有数据后，在 AsyncTask 中的适配器上调用 notifyDataSetChanged():

          // looping through All Contacts
          for (int i = 0; i < classes.length(); i++) {
              JSONObject c = classes.getJSONObject(i);
  
              prgmNameList.add("lesson_" + c.getString("id"));
              caseList.add(c.getString("course"));
              dateList.add(c.getString("date"));
          }
  
          adapter.notifyDataSetChanged();
  
          return "Load Complete";