我目前有一个ViewPager，其中包括三个片段作为页面。前两个页面显示的是由RSS源使用AsyncTask构建的自定义列表视图的片段。但是，当应用程序运行时，只有一个列表视图被显示出来，另一个页面则是空白的。（注意：我在这个项目中使用了ViewPagerIndicator）。
主活动:
public class ViewPagerExample extends FragmentActivity {
private static final String[] TITLETAB = new String[] { "Latest", "New", "Misc" };
private MyAdapter mAdapter;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.simple_tabs);
mAdapter = new MyAdapter(getSupportFragmentManager());
mPager = (ViewPager)findViewById(R.id.pager);
mPager.setAdapter(mAdapter);
mIndicator = (TabPageIndicator)findViewById(R.id.indicator);
mIndicator.setViewPager(mPager);
mIndicator.setCurrentItem(1);
}
public static class MyAdapter extends FragmentPagerAdapter {
public MyAdapter(FragmentManager fm) {
super(fm);
}
@Override
public int getCount() {
return ViewPagerExample.TITLETAB.length;
}
@Override
public Fragment getItem(int position) {
switch(position) {
case 0:
return new CustomizedListView();
case 1:
return new CustomizedListViewn();
default:
return null;
}
}
@Override
public CharSequence getPageTitle(int position) {
return ViewPagerExample.TITLETAB[position % ViewPagerExample.TITLETAB.length].toUpperCase();
}
@Override
public void destroyItem(View collection, int position, Object view) {
((ViewPager) collection).removeView((View) view);
}
}}
列表视图片段：
public class CustomizedListView extends Fragment {
// All static variables
static final String URL = "http://url.net/booking/music.xml";
// XML node keys
static final String KEY_SONG = "song"; // parent node
static final String KEY_ID = "id";
static final String KEY_TITLE = "title";
static final String KEY_ARTIST = "artist";
static final String KEY_DURATION = "duration";
static final String KEY_THUMB_URL = "thumb_url";
ListView list;
LazyAdapter adapter;
XMLParser parser = new XMLParser();
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
new getFeed().execute();
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState)
{
View thisfragment1 = inflater.inflate(R.layout.main, container, false);
return thisfragment1;
}
private class getFeed extends AsyncTask<Void, Void, Document> {
@Override
protected Document doInBackground(Void... params) {
XMLParser parser = new XMLParser();
String xml = parser.getXmlFromUrl(URL); // getting XML from URL
Document doc = parser.getDomElement(xml); // getting DOM element
return doc;
}
@Override
protected void onPostExecute(Document doc) {
ArrayList<HashMap<String, String>> songsList = new ArrayList<HashMap<String, String>>();
NodeList nl = doc.getElementsByTagName(KEY_SONG);
// looping through all song nodes <song>
for (int i = 0; i < nl.getLength(); i++) {
// creating new HashMap
HashMap<String, String> map = new HashMap<String, String>();
Element e = (Element) nl.item(i);
// adding each child node to HashMap key => value
map.put(KEY_ID, parser.getValue(e, KEY_ID));
map.put(KEY_TITLE, parser.getValue(e, KEY_TITLE));
map.put(KEY_ARTIST, parser.getValue(e, KEY_ARTIST));
map.put(KEY_DURATION, parser.getValue(e, KEY_DURATION));
map.put(KEY_THUMB_URL, parser.getValue(e, KEY_THUMB_URL));
// adding HashList to ArrayList
songsList.add(map);
}
list=(ListView)getActivity().findViewById(R.id.list);
// Getting adapter by passing xml data ArrayList
adapter=new LazyAdapter(getActivity(), songsList);
list.setAdapter(adapter);
// Click event for single list row
list.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
}
});
}
}}
第二个片段与上面完全相同，只是RSS提要的URL不同。非常感谢您的帮助。谢谢。