I want to understand this exception in order to implement a proper fix.
Overview:
There's a ViewPager and it uses a FragmentStatePagerAdapter to instantiate
2 fragments via getItem and MyFragmentClass.newInstance(...).
Adapter's getItem looks like this:
@Override
public Fragment getItem(int position) {
Fragment fragment = null;
switch(position) {
case 0:
fragment = MyFragment2.newInstance(par1);
break;
case 1:
fragment = MyFragment2.newInstance(par2, par3);
break;
}
return fragment;
}
Problem:
When the activity is destroyed, and created again, the adapter is
intantiated again, the fragments created again with
MyFragmentClass.newInstance(...)... but then on this line:
pager.setAdapter(adapter);
I get the mentioned exception.
I looked in the source where the exception is thrown, it's this:
@Override
public Fragment getFragment(Bundle bundle, String key) {
int index = bundle.getInt(key, -1);
if (index == -1) {
return null;
}
if (index >= mActive.size()) {
throw new IllegalStateException("Fragement no longer exists for
key "
+ key + ": index " + index);
}
Fragment f = mActive.get(index);
if (f == null) {
throw new IllegalStateException("Fragement no longer exists for
key "
+ key + ": index " + index);
}
return f;
}
So, a bundle is passed there, with some state which references my old
fragments, but this doesn't correspond to the current state (mActive), and
the exceptio is thrown.
I don't understand what's the idea behind this, or which way I'm actually
supposed to instantiate the fragments... so I have no idea how to solve.
I also tried some trick I got from some other context:
pager.setOffscreenPageLimit(1);
In order to avoid that the fragments are destroyed when they are off screen
(in the case of 2 pages viewpager, although don't know if it works well
with state adapter). But don't seems to be related, at least, it doesn't
help, still get the same exception.
Please help, thanks in advance.
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