我正在尝试从扩展片段的类中将listview添加到我的布局中。问题是，当数据到来时，布局显示空指针异常。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/";
public LayoutInflater inflater;
ListView listView;
@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);
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) {
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);
}
});
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) {
---------------------- Logcat error takes me here----------------------------
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("");
listView.setAdapter(null);
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());
listView.setAdapter(adapter);
}
}
}
logcat的：
07-03 00:21:38.253: E/AndroidRuntime(27831): FATAL EXCEPTION: main
07-03 00:21:38.253: E/AndroidRuntime(27831): java.lang.NullPointerException
07-03 00:21:38.253: E/AndroidRuntime(27831): at akshat.jaiswal.newshelf.TopStoriesFragment$MyCustomAdapter.getView(TopStoriesFragment.java:129)
07-03 00:21:38.253: E/AndroidRuntime(27831): at android.widget.AbsListView.obtainView(AbsListView.java:2207)
07-03 00:21:38.253: E/AndroidRuntime(27831): at android.widget.ListView.measureHeightOfChildren(ListView.java:1250)
07-03 00:21:38.253: E/AndroidRuntime(27831): at android.widget.ListView.onMeasure(ListView.java:1162)
07-03 00:21:38.253: E/AndroidRuntime(27831): at android.view.View.measure(View.java:15609)
07-03 00:21:38.253: E/AndroidRuntime(27831): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4916)
07-03 00:21:38.253: E/AndroidRuntime(27831): at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1411)
07-03 00:21:38.253: E/AndroidRuntime(27831): at android.widget.LinearLayout.measureVertical(LinearLayout.java:698)
07-03 00:21:38.253: E/AndroidRuntime(27831): at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
07-03 00:21:38.253: E/AndroidRuntime(27831): at android.view.View.measure(View.java:15609)
07-03 00:21:38.253: E/AndroidRuntime(27831): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4916)
07-03 00:21:38.253: E/AndroidRuntime(27831): at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
07-03 00:21:38.253: E/AndroidRuntime(27831): at android.view.View.measure(View.java:15609)
07-03 00:21:38.253: E/AndroidRuntime(27831): at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1451)
07-03 00:21:38.253: E/AndroidRuntime(27831): at android.view.View.measure(View.java:15609)
07-03 00:21:38.253: E/AndroidRuntime(27831): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4916)
07-03 00:21:38.253: E/AndroidRuntime(27831): at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
07-03 00:21:38.253: E/AndroidRuntime(27831): at android.view.View.measure(View.java:15609)
07-03 00:21:38.253: E/AndroidRuntime(27831): at android.widget.LinearLayout.measureVertical(LinearLayout.java:850)
07-03 00:21:38.253: E/AndroidRuntime(27831): at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
07-03 00:21:38.253: E/AndroidRuntime(27831): at android.view.View.measure(View.java:15609)
07-03 00:21:38.253: E/AndroidRuntime(27831): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4916)
07-03 00:21:38.253: E/AndroidRuntime(27831): at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
07-03 00:21:38.253: E/AndroidRuntime(27831): at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2191)
07-03 00:21:38.253: E/AndroidRuntime(27831): at android.view.View.measure(View.java:15609)
07-03 00:21:38.253: E/AndroidRuntime(27831): at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2165)
07-03 00:21:38.253: E/AndroidRuntime(27831): at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1249)
07-03 00:21:38.253: E/AndroidRuntime(27831): at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1443)
07-03 00:21:38.253: E/AndroidRuntime(27831): at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1139)
07-03 00:21:38.253: E/AndroidRuntime(27831): at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4879)
07-03 00:21:38.253: E/AndroidRuntime(27831): at android.view.Choreographer$CallbackRecord.run(Choreographer.java:776)
07-03 00:21:38.253: E/AndroidRuntime(27831): at android.view.Choreographer.doCallbacks(Choreographer.java:579)
07-03 00:21:38.253: E/AndroidRuntime(27831): at android.view.Choreographer.doFrame(Choreographer.java:548)
07-03 00:21:38.253: E/AndroidRuntime(27831): at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:762)
07-03 00:21:38.253: E/AndroidRuntime(27831): at android.os.Handler.handleCallback(Handler.java:725)
07-03 00:21:38.253: E/AndroidRuntime(27831): at android.os.Handler.dispatchMessage(Handler.java:92)
07-03 00:21:38.253: E/AndroidRuntime(27831): at android.os.Looper.loop(Looper.java:153)
07-03 00:21:38.253: E/AndroidRuntime(27831): at android.app.ActivityThread.main(ActivityThread.java:5297)
07-03 00:21:38.253: E/AndroidRuntime(27831): at java.lang.reflect.Method.invokeNative(Native Method)
07-03 00:21:38.253: E/AndroidRuntime(27831): at java.lang.reflect.Method.invoke(Method.java:511)
07-03 00:21:38.253: E/AndroidRuntime(27831): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)
07-03 00:21:38.253: E/AndroidRuntime(27831): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
07-03 00:21:38.253: E/AndroidRuntime(27831): at dalvik.system.NativeStart.main(Native Method)
Row.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="wrap_content"
android:layout_margin="4dp"
android:background="@android:color/darker_gray"
android:orientation="vertical">
<TextView
android:id="@+id/listtitle"
android:layout_marginTop="1dp"
android:layout_width="fill_parent"
android:textAppearance="@android:style/TextAppearance.Medium"
android:layout_height="wrap_content"/>
<TextView
android:id="@+id/listpubdate"
android:layout_marginBottom="1dp"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:textAppearance="@android:style/TextAppearance.Small"/>
</LinearLayout>
答案 0 :(得分：2)
您尚未初始化inflater中使用的getView()成员变量。
使用例如inflater = LayoutInflater.from(context)初始化它。