get fragment by tag or id from tablayout ,android

Question

i use this tutorial for creating tab. and now i have a recyclerview in each fragment and i want to notify them from mainactivity. how to access the adapter in fragment?

Answer 1

EDIT: After many test, the previous answer work with Android < 21, but for Android > 21 it's little bit weird, it doesn't seems to work in the same way.

Finally, I solved it like that, and it works everywhere:

In your adapter:

    HashMap mPageReferenceMap = new HashMap<>();
@Override
public Object instantiateItem(ViewGroup container, int position) {
    Fragment fragment = (Fragment) super.instantiateItem(container, position);
    mPageReferenceMap.put(position, fragment);
    return fragment;
}

@Override
public void destroyItem(ViewGroup container, int position, Object object) {
    super.destroyItem(container, position, object);
    mPageReferenceMap.remove(position);
}
public Fragment getFragment(int key) {
    return mPageReferenceMap.get(key);
}

And you call getFragment where you want in your activity like that:

int index = viewPager.getCurrentItem();
ViewPagerAdapter adapter = ((ViewPagerAdapter)viewPager.getAdapter());
final YourFragment tabFragment = (YourFragment) adapter.getFragment(index);

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PREVIOUS ANSWER :

Warning : it doesn't really work with Android > 21

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I had the same problem. Finally, i did'nt use id or tag.

Instead of using:

CustomFragment customFragment = (CustomFragment) getSupportFragmentManager().findFragmentByTag(getString(R.string.fragment_custo_tag));

use this:

CustomFragment customFragment = (CustomFragment) getSupportFragmentManager().getFragments().get(0);

to get instance of CustomFragment.

I have put get(0) as your position of CustomFragment instance is at zero.

I found this issue here: Set and get using tag a fragment in android