How to prevent leaking Fragment

Question

I have the following Activity:

class SwitchFragAct extends AppCompatActivity {
  Fragment a;
  Fragment b;

  onClickSwitchFrags(View v) {
    FragmentManager mgr = getSupportFragmentManager();
    Fragment currentFrag = mgr.findFragmentById(R.id.frag_to_swap);
    
    if (currentFrag == a) {
       mgr.beginTransaction().detach(a).attach(b).commit();
    } else if (currentFrag == b) {
       mgr.beginTransaction().detach(b).attach(a).commit();
    }
  }
}

So leak canary will complain the that the unattached fragment is leaking (e.g. @ SwitchFragAct#a) . What is my alternative to make sure it doesn't leak? I think I need to use attach/detach so the state is still being saved. I think the only alternative is to recreate the fragment every time. Currently there aren't any mechanisms to do so in that fragment where I can pass in saved state.

Answer 1

Use replace. The replace method removes the current fragment and adds a new fragment in its place.

class SwitchFragAct extends AppCompatActivity {
  Fragment a;
  Fragment b;

  onClickSwitchFrags(View v) {
    FragmentManager mgr = getSupportFragmentManager();
    Fragment currentFrag = mgr.findFragmentById(R.id.frag_to_swap);
    
    if (currentFrag == a) {
       mgr.beginTransaction().replace(R.id.frag_to_swap, b).commit();
    } else if (currentFrag == b) {
       mgr.beginTransaction().replace(R.id.frag_to_swap, a).commit();
    }
  }
}