我有一个FragmentPagerAdapter。它的getItem
方法可以根据外部数据返回一个片段。当我更新要显示的数据后,我调用notifyDataSetChanged
,但仍然没有任何反应。我确实重写了getItemPosition
方法,返回POSITION_NONE
:
public static class TabsAdapter extends FragmentPagerAdapter implements TabHost.OnTabChangeListener,
ViewPager.OnPageChangeListener
{
private final Context mContext;
private final TabHost mTabHost;
private final ViewPager mViewPager;
private final ArrayList<TabInfo> mTabs = new ArrayList<TabInfo>();
private PagerTabsFragments fragmentDisplayInfo = null; // for now only a
// single size
// back
// stack
static class PagerTabsFragments
{
public int tabPosition;
public Fragment fragmentToDisplay;
public Object fragmentInfo;
public PagerTabsFragments(int tab, Fragment frag, Object info)
{
tabPosition = tab;
fragmentToDisplay = frag;
fragmentInfo = info;
}
}
public void SetFragmentToDisplay(int tabPosition, Fragment frag, Object info)
{
fragmentDisplayInfo = new PagerTabsFragments(tabPosition, frag, info);
notifyDataSetChanged();
}
public void CancelFragmentToDisplay()
{
fragmentDisplayInfo = null;
}
...
@Override
public Fragment getItem(final int position)
{
if ((fragmentDisplayInfo != null) && (fragmentDisplayInfo.tabPosition == position))
{
return fragmentDisplayInfo.fragmentToDisplay;
}
final TabInfo info = mTabs.get(position);
return Fragment.instantiate(mContext, info.clss.getName(), info.args);
}
@Override
public int getItemPosition(Object item)
{
if (fragmentDisplayInfo == null)
{
return super.getItemPosition(item);
}
return POSITION_NONE;
}
...
而外部更新是在一个点击事件中设置fragmentDisplayInfo
变量。我进行了调试并看到fragmentDisplayInfo
确实已经被初始化,getItemPosition
方法确实返回POSITION_NONE
,但getItem
方法甚至没有被调用。这是为什么呢?
编辑:
如果您还没有这样做,请注意适配器的重写部分:
@Override
public int getItemPosition(Object item)
{
return POSITION_NONE;
}