Update Fragment from ViewPager

Solution 1:

Update Fragment from ViewPager

You need to implement getItemPosition(Object obj) method.

This method is called when you call

notifyDataSetChanged()

on your ViewPagerAdaper. Implicitly this method returns POSITION_UNCHANGED value that means something like this: "Fragment is where it should be so don't change anything."

So if you need to update Fragment you can do it with:

• Always return POSITION_NONE from getItemPosition() method. It which means: "Fragment must be always recreated"
• You can create some update() method that will update your Fragment(fragment will handle updates itself)

Example of second approach:

public interface Updateable {
   public void update();
}


public class MyFragment extends Fragment implements Updateable {

   ...

   public void update() {
     // do your stuff
   }
}

And in FragmentPagerAdapter you'll do something like this:

@Override
public int getItemPosition(Object object) {
   MyFragment f = (MyFragment ) object;
   if (f != null) {
      f.update();
   }
  return super.getItemPosition(object);
}

And if you'll choose first approach it can looks like:

@Override
public int getItemPosition(Object object) {
   return POSITION_NONE;
}

Note: It's worth to think a about which approach you'll pick up.

Solution 2:

I faced problem some times so that in this case always avoid FragmentPagerAdapter and use FragmentStatePagerAdapter.

It work for me. I hope it will work for you also.

Solution 3:

I implement a app demo following Sajmon's answer. Just for anyone else who search this question.

You can access source code on GitHub

Solution 4:

In your PagerAdapter override getItemPosition

@Override
public int getItemPosition(Object object) {
// POSITION_NONE makes it possible to reload the PagerAdapter
return POSITION_NONE;
}

After that add viewPager.getAdapter().notifyDataSetChanged(); this code like below

viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
        @Override
        public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

        }

        @Override
        public void onPageSelected(int position) {
            viewPager.getAdapter().notifyDataSetChanged();
        }

        @Override
        public void onPageScrollStateChanged(int state) {

        }
    });

should work.