java - 将 ListView 添加到 fragment 给出错误

Question

我正在尝试将自定义 ListView 添加到扩展 fragment 的类中。但它在 4 个地方给出了错误。这是代码:

TopStoriesFragment.java

public class TopStoriesFragment extends Fragment {

    public String thehindu = "http://www.thehindu.com/news/?service=rss";
    public String toi = "http://timesofindia.feedsportal.com/c/33039/f/533965/index.rss";
    public String reuters = "http://feeds.reuters.com/reuters/topNews";
    public String deccanherald = "http://www.deccanherald.com/rss-internal/top-stories.rss";
    public String currenturl = thehindu;
    AlertDialog levelDialog;
    public String fakingnews = "http://thepuntended.wordpress.com/";

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

        View rootView = inflater.inflate(R.layout.fragment_top_rated, container, false);

        feedTitle = (TextView) rootView.findViewById(R.id.feedtitle);
        feedDescribtion = (TextView) rootView.findViewById(R.id.feeddescribtion);

        startReadRss();

        return rootView;
    }

    public class RssLoadingTask extends AsyncTask<Void, Void, Void> {

        @Override
        protected void onPostExecute(Void result) {
            // TODO Auto-generated method stub
            displayRss();
        }

        @Override
        protected void onPreExecute() {
            // TODO Auto-generated method stub
            preReadRss();
        }

        @Override
        protected void onProgressUpdate(Void... values) {
            // TODO Auto-generated method stub
            // super.onProgressUpdate(values);
        }

        @Override
        protected Void doInBackground(Void... arg0) {
            // TODO Auto-generated method stub
            readRss();
            return null;
        }

    }

    private RSSFeed myRssFeed = null;

    TextView feedTitle;
    TextView feedDescribtion;

    // TextView feedPubdate;
    // TextView feedLink;

    public class MyCustomAdapter extends ArrayAdapter<RSSItem> {

        public MyCustomAdapter(Context context, int textViewResourceId,
                List<RSSItem> list) {
            super(context, textViewResourceId, list);
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            // TODO Auto-generated method stub
            // return super.getView(position, convertView, parent);

            View row = convertView;
            if (row == null) {

    //------------------------------- Error 1-------------------------------
                LayoutInflater inflater = getLayoutInflater();
    //------------------------------- Error 1-------------------------------

                row = inflater.inflate(R.layout.row, parent, false);
            }

            TextView listTitle = (TextView) row.findViewById(R.id.listtitle);
            listTitle.setText(myRssFeed.getList().get(position).getTitle());
            TextView listPubdate = (TextView) row
                    .findViewById(R.id.listpubdate);
            listPubdate.setText(myRssFeed.getList().get(position).getPubdate());

            if (position % 2 == 0) {
                listTitle.setBackgroundColor(0xff101010);
                listPubdate.setBackgroundColor(0xff101010);
            } else {
                listTitle.setBackgroundColor(0xff080808);
                listPubdate.setBackgroundColor(0xff080808);
            }

            return row;
        }
    }

    private void startReadRss() {
        new RssLoadingTask().execute();
    }

    private void preReadRss() {
        feedTitle.setText("--- wait ---");
        feedDescribtion.setText("");
        // feedPubdate.setText("");
        // feedLink.setText("");

    //------------------------------- Error 2 (Solved)-------------------------------
        setListAdapter(null);
    //------------------------------- Error 2-------------------------------

        Toast.makeText(getActivity(), "Reading RSS, Please wait.", Toast.LENGTH_LONG)
                .show();
    }

    private void readRss() {

        try {
            URL rssUrl = new URL(currenturl);
            SAXParserFactory mySAXParserFactory = SAXParserFactory
                    .newInstance();
            SAXParser mySAXParser = mySAXParserFactory.newSAXParser();
            XMLReader myXMLReader = mySAXParser.getXMLReader();
            RSSHandler myRSSHandler = new RSSHandler();
            myXMLReader.setContentHandler(myRSSHandler);
            InputSource myInputSource = new InputSource(rssUrl.openStream());
            myXMLReader.parse(myInputSource);

            myRssFeed = myRSSHandler.getFeed();

        } catch (MalformedURLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (ParserConfigurationException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (SAXException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    private void displayRss() {
        if (myRssFeed != null) {
            Calendar c = Calendar.getInstance();
            // String strCurrentTiime = "\n(Time of Reading - "
            // + c.get(Calendar.HOUR_OF_DAY)
            // + " Hrs. : "
            // + c.get(Calendar.MINUTE) + " Mins.)\n" +c.get(Calendar.AM_PM);

            SimpleDateFormat sdf = new SimpleDateFormat(
                    "MMMM-dd-yyyy HH:mm:ss a");
            String strCurrentTiime = sdf.format(c.getTime());

            feedTitle.setText(myRssFeed.getTitle());
            feedDescribtion.setText(strCurrentTiime);
            // feedPubdate.setText(myRssFeed.getPubdate());
            // feedLink.setText(myRssFeed.getLink());

            MyCustomAdapter adapter = new MyCustomAdapter(getActivity(), R.layout.row,
                    myRssFeed.getList());

   //------------------------------- Error 3 (Solved)-------------------------------
            setListAdapter(adapter);
   //------------------------------- Error 3-------------------------------

        }
    }

    @Override
   //------------------------------- Error 4 (Solved)-------------------------------
    protected void onListItemClick(ListView l, View v, int position, long id) {
   //------------------------------- Error 4-------------------------------
        // TODO Auto-generated method stub
        Intent intent = new Intent(getActivity(), ShowDetails.class);
        Bundle bundle = new Bundle();
        bundle.putString("keyTitle", myRssFeed.getItem(position).getTitle());
        bundle.putString("keyDescription", myRssFeed.getItem(position)
                .getDescription());
        bundle.putString("keyLink", myRssFeed.getItem(position).getLink());
        bundle.putString("keyPubdate", myRssFeed.getItem(position).getPubdate());
        intent.putExtras(bundle);
        startActivity(intent);
    }
}

顶级 Fragment.xml

<?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="fill_parent"
    android:orientation="vertical" >

    <LinearLayout 
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:background="@drawable/back"
    android:orientation="vertical" >

    <TextView
        android:id="@+id/feedtitle"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textColor="@color/Black"
        android:layout_gravity="center"
        android:layout_marginTop="10dp"
        android:textStyle="bold" />

    <TextView
        android:textColor="@color/Black"
        android:id="@+id/feeddescribtion"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal" />

    </LinearLayout>

    <ListView
        android:id="@android:id/list"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:divider="@drawable/divider" />

    <TextView
        android:id="@android:id/empty"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="No Data" />

</LinearLayout>

有错误的4处已在行间标出。错误是:

**1:Fragment 类型中的方法 getLayoutInflater(Bundle) 不适用于参数 () **

2:TopStoriesFragment 类型未定义 setListAdapter(null) 方法(通过扩展 ListFragment 而不是 Fragment 来解决。)

3:TopStoriesFragment 类型未定义 setListAdapter(TopStoriesFragment.MyCustomAdapter) 方法(通过扩展 ListFragment 而不是 Fragment 来解决。)

4:TopStoriesFragment类型的方法onListItemClick(ListView, View, int, long)必须重写或实现父类(super class)型方法(通过在方法中添加public来解决)

Answer 1

您的问题似乎可以通过扩展 ListFragment 而不是 Fragment 来解决，但您说您不能这样做。因此，让我们一次一个地解决您的问题:

1: The method getLayoutInflater(Bundle) in the type Fragment is not applicable for the arguments ()

正如 @G3rcar 所建议的，您可以声明一个 LayoutInflater 成员字段，使用传递给 onCreateView 方法的 LayoutInflater 对其进行初始化，然后使用你后面的代码中的那个。或者，您可以随时在 MyCustomAdapter.getView() 中检索 LayoutInflater，方法是:

LayoutInflater inflater = (LayoutInflater) getContext().getSystemService(
    Context.LAYOUT_INFLATER_SERVICE);

2: The method setListAdapter(null) is undefined for the type TopStoriesFragment (Solved by extending ListFragment instead of Fragment.)

从您的代码来看，您可以简单地消除此调用。或者，请参阅我对下一个问题的建议。

3: The method setListAdapter(TopStoriesFragment.MyCustomAdapter) is undefined for the type TopStoriesFragment (Solved by extending ListFragment instead of Fragment.)

解决这个问题和上一个问题的方法是在第一次构造 fragment View 时存储对 ListView 的引用:

TextView feedTitle;
TextView feedDescribtion;
ListView listView;

public View onCreateView(...) {
    ...
    feedTitle = (TextView) rootView.findViewById(R.id.feedtitle);
    feedDescribtion = (TextView) rootView.findViewById(R.id.feeddescribtion);
    listView = (ListView) rootView.findViewById(android.R.id.list);
    ...
}

然后就可以直接为listView设置适配器了:

private void displayRss() {
    ...
    listView.setAdapter(adapter); // instead of "setAdapter(adapter)"
}

4: The method onListItemClick(ListView, View, int, long) of type TopStoriesFragment must override or implement a supertype method (Solved by adding public to the method)

您可以显式设置OnItemClickListener让 ListView 响应项目点击:

listView = (ListView) rootView.findViewById(android.R.id.list);
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
    @Override
    public void onItemClick(AdapterView<?> parent, View v, int position, long id) {
       ... // body of your current onListItemClick() method
    }
});

然后，您可以从 TopStoriesFragment 中删除 onListItemClick 方法。