Need to identify current view fragment from pager adapter

Question

We have to know the current fragment which is the visible mode in pager adapter, but unable to process.

for (Fragment fragment : getChildFragmentManager().getFragments()) {
    if (fragment instanceof OffLineSyncedFragment && fragment.isVisible() && fragment.isVisible()) {
        ((OffLineSyncedFragment) fragment).confirmDeleteAlert(getActivity(), documentHelper, false, isDocument, null);
    }
    else if(fragment instanceof OffLineFailedFragment && fragment.isVisible()){

    }
}

This is my code which is not working.

give your fragments a tag and use that tag to identify the fragment — Ezio, May 18 '17 at 05:55
There are several ways to do this based on the purpose. If you can say why exactly you want to query the active fragment, I can provide the relevant solution. — Mohammed Atif, May 18 '17 at 05:58

score 0 · Answer 1 · answered May 18 '17 at 05:58

0

ViewPager.OnPageChangeListener is the correct approach here. And as you have noticed, onPageSelected(int position) doesn't get called until the page is centered. So when the page is properly centered it will give you the fragment that is currently visible.,

answered May 18 '17 at 05:58

Anmol317

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Do you really think onPageSelected works in this case? – Mohammed Atif May 18 '17 at 05:59
Yes it works fine when the page is changed to get the current fragment that is visible. – Anmol317 May 18 '17 at 06:00
Please make a try, your approach will work if and only if there a list of fragments. In general case your approach will return the new instance of same fragment at that position which is nearly useless for any updates. – Mohammed Atif May 18 '17 at 06:03
Yeam you are right it will only work if he have a list of fragments, which can be defined. – Anmol317 May 18 '17 at 06:05
I generally do not prefer having list of fragments. It will create unnecessary memory overhead – Mohammed Atif May 18 '17 at 06:07

score 0 · Answer 2 · answered May 18 '17 at 05:59

There is some ways to do it. first easy and straight you can set page change listener on your view pager :

  viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
    @Override
    public void onPageScrolled(final int i, final float v, final int i2) {
    }
    @Override
    public void onPageSelected(final int i) {
        // If you are user FragmentPagerAdapter below is the right way to get fragment
        Fragment fragment= getChildFragmentManager().findFragmentByTag("android:switcher:" + R.id.viewPager_card_exchanger + ":" + i);

        if(fragment!=null){
            // Do your stuff here 
        }
    }
    @Override
    public void onPageScrollStateChanged(final int i) {
    }
});

Or You can override the the fragment method as below:

 @Override
public void setUserVisibleHint(boolean isVisibleToUser) {
    super.setUserVisibleHint(isVisibleToUser);
    if (isVisibleToUser) {
        System.out.println("VISIBLE");
    } else {
        System.out.println("GONE");
    }
}

Need to identify current view fragment from pager adapter

2 Answers2