Refresh fragment when change between tabs

Question

App open on first fragment and there is 2 tabs i want to refresh second fragment when i move to it but i don\'t want to refresh first fragment

MainActivity

Answer 1

Inside Your fragment class use the below code:

@Override
public void setUserVisibleHint(boolean isVisibleToUser) {
    super.setUserVisibleHint(isVisibleToUser);
    if (isVisibleToUser) {
        getFragmentManager().beginTransaction().detach(this).attach(this).commit();
    }
}

Answer 2

As of 2020 it is advisable to use architecture components(MVVM) such as LiveData and viewModel

This way all Fragments can share the same state

see docs here https://developer.android.com/jetpack/guide

Answer 3

Try This

ViewPager mViewPager = (ViewPager)findViewById(R.id.pager);
mViewPager.setOffscreenPageLimit(2); 

Answer 4

When a Fragment is made visible (i.e., the selected page in your ViewPager), its setUserVisibleHint() method is called. You can override that method in your TwoFragment and use it to trigger a refresh.

public class TwoFragment extends Fragment {

  @Override
  public void setUserVisibleHint(boolean isVisibleToUser) {
    super.setUserVisibleHint(isVisibleToUser);
    if (isVisibleToUser) {
      // Refresh your fragment here
    }
  }

Answer 5

If you wouldn't mind refreshing every fragment every time a tab changes, you could simply override the getItemPosition() method of your FragmentPagerAdapter and make it return always the value POSITION_NONE. Example:

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

By doing that, you tell android to refresh the fragment each time the view pager tries to get it. Performance wise, it isn't the best practice. So there is a second approach:

First, create an interface to be called when your need refresh:

public interface Updatable {
   public void update();
}

Then, make your fragments implement this interface:

public class MyFragment extends Fragment implements Updateable {

   ...

   @Override
   public void update() {
     // refresh your fragment, if needed
   }
}

If your really wish to not update your first fragment, do nothing in its update() method.

Third, override the getItemPosition method and call update(). This will be called every time a fragment gets selected:

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

Most of this code came from this answer.