I got a FragmentPagerAdapter. It's getItem
method can return a fragment according to data it has from the outside. After I update the data its suppose to display I call notifyDataSetChanged
and yet nothing happened. I DID override the getItemPosition
method to return 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;
}
...
And the update from outside is in a click event which sets the fragmentDisplayInfo
var.
I debuged and saw that the fragmentDisplayInfo
is indeed initialized and the getItemPosition
method does return POSITION_NONE
, but the getItem method is not even called. Why is that?
EDIT:
If you hadn't done so as well, please notice that overiden part of the adapter:
@Override
public int getItemPosition(Object item)
{
return POSITION_NONE;
}
What Nik Myers is saying is correct. However there is a piece missing. When notifyDataSetChanged is called, the method getItemPosition is called. You need to override this to get the fragments to reload.
@Override
public int getItemPosition(Object object) {
// Causes adapter to reload all Fragments when
// notifyDataSetChanged is called
return POSITION_NONE;
}