Remove Old Fragment from Fragment Manager

If you want to replace a fragment with another, you should have added them dynamically, first of all. Fragments that are hard coded in XML, cannot be replaced.

// Create new fragment and transaction
Fragment newFragment = new ExampleFragment();
FragmentTransaction transaction = getFragmentManager().beginTransaction();

// Replace whatever is in the fragment_container view with this fragment,
// and add the transaction to the back stack
transaction.replace(R.id.fragment_container, newFragment);
transaction.addToBackStack(null);

// Commit the transaction
transaction.commit();

Refer this post: Replacing a fragment with another fragment inside activity group

Refer1: Replace a fragment programmatically

I had the same issue to remove old fragments. I ended up clearing the layout that contained the fragments.

LinearLayout layout = (LinearLayout) a.findViewById(R.id.layoutDeviceList);
layout.removeAllViewsInLayout();
FragmentTransaction ft = getFragmentManager().beginTransaction();
...

I do not know if this creates leaks, but it works for me.

I had the same issue. I came up with a simple solution. Use fragment .replace instead of fragment .add. Replacing fragment doing the same thing as adding fragment and then removing it manually.

getFragmentManager().beginTransaction().replace(fragment).commit();

instead of

getFragmentManager().beginTransaction().add(fragment).commit();

Probably you instance old fragment it is keeping a reference. See this interesting article Memory leaks in Android — identify, treat and avoid

If you use addToBackStack, this keeps a reference to instance fragment avoiding to Garbage Collector erase the instance. The instance remains in fragments list in fragment manager. You can see the list by

ArrayList<Fragment> fragmentList = fragmentManager.getFragments();

The next code is not the best solution (because don´t remove the old fragment instance in order to avoid memory leaks) but removes the old fragment from fragmentManger fragment list

int index = fragmentManager.getFragments().indexOf(oldFragment);
fragmentManager.getFragments().set(index, null);

You cannot remove the entry in the arrayList because apparenly FragmentManager works with index ArrayList to get fragment.

I usually use this code for working with fragmentManager

public void replaceFragment(Fragment fragment, Bundle bundle) {

    if (bundle != null)
        fragment.setArguments(bundle);

    FragmentManager fragmentManager = getSupportFragmentManager();
    FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
    Fragment oldFragment = fragmentManager.findFragmentByTag(fragment.getClass().getName());

    //if oldFragment already exits in fragmentManager use it
    if (oldFragment != null) {
        fragment = oldFragment;
    }

    fragmentTransaction.replace(R.id.frame_content_main, fragment, fragment.getClass().getName());

    fragmentTransaction.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE);

    fragmentTransaction.commit();
}

I had issue with onBackPress. i did'nt want to return to old fragments.

This is worked for me to remove old fragments from fragment manager :

FragmentManager fm = getSupportFragmentManager();
fm.popBackStack(null, FragmentManager.POP_BACK_STACK_INCLUSIVE);

You can also use an if block like this :

FragmentManager fm = getSupportFragmentManager();

if (fm.getBackStackEntryCount() > 0) {
    fm.popBackStack(null, FragmentManager.POP_BACK_STACK_INCLUSIVE);
}

In Kotlin

  val fragList  = f.supportFragmentManager.fragments
    for (fragment in fragList) {
        f.supportFragmentManager.beginTransaction().remove(fragment).commit()
    }