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popBackStack causes calling oncreateView of fragment again and again

I have 3 fragment A, B,C.I wrote piece of code for replacing them and maintaining backstack:

 public void addFragment(Fragment fragmentToAdd, String fragmentTag) {
        FragmentManager supportFragmentManager = getSupportFragmentManager();
        Fragment activeFragment = getActiveFragment();
        FragmentTransaction fragmentTransaction = supportFragmentManager
                .beginTransaction();
        if (null != activeFragment) {
            fragmentTransaction.hide(activeFragment);
        }
        fragmentTransaction.replace(R.id.layout_child_activity, fragmentToAdd,
                fragmentTag);

       if (supportFragmentManager.getBackStackEntryCount() > 1) {
            supportFragmentManager.popBackStack();
        }
        fragmentTransaction.addToBackStack(fragmentTag);
        fragmentTransaction.commit();
    }

Here in this piece of code

if (supportFragmentManager.getBackStackEntryCount() > 1) {
    supportFragmentManager.popBackStack();
}

I using for pop the latest fragment if stack length is more than 1. Now due to this when length is going greater than 1 than it is calling onCreate view again and again. Like :

  1. open A.
  2. open B.
  3. open C.(In case of open C. onCreateView of A is called. )

Why I am getting such kind of behavior ? When I am removing that italic code than it is not happening.

like image 534
Anshul Avatar asked Mar 09 '14 04:03

Anshul


1 Answers

Than behavior is normal, coming from the backstack transaction, as the docs say. The backstack never saves Fragments, it just saves the transaction

enter image description here

http://developer.android.com/intl/es/guide/components/fragments.html

What I do, I am not sure if, is it the best way but when I want to clear all the transactions I do this

1) INSIDE YOUR ACTIVITY check if is there any transactions in the back stack, and add a flag inside your fragment, in your case is A

       int backStackCount = getSupportFragmentManager().getBackStackEntryCount();

       if(backStackCount > 0) {
           Transactions.MUST_DETACH_FROM_BACKSTACK = true;
           getSupportFragmentManager().popBackStackImmediate(null, FragmentManager.POP_BACK_STACK_INCLUSIVE);
       }

2) Inside your fragment A, get the flag and Remove the fragment onCreateView and return null like this

public class Transactions extends android.support.v4.app.Fragment{

public static boolean MUST_DETACH_FROM_BACKSTACK = false;

public Transactions() {
    // Required empty public constructor
}


@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    Log.i("FRAGMENT", "onCreateView "+MUST_DETACH_FROM_BACKSTACK);
    // Inflate the layout for this fragment
    if (MUST_DETACH_FROM_BACKSTACK) {
        MUST_DETACH_FROM_BACKSTACK = false;
        getActivity().getSupportFragmentManager().beginTransaction().remove(this).commit();
        return null;
    }
    return inflater.inflate(R.layout.fragment_transactions, container, false);
}

@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);


    Log.i("FRAGMENT", "onViewCreated");
    if(view != null){

        Log.i("FRAGMENT", "ThreadStarted");
        startThread(view);
    }
}

BUT BE CAREFULL I Get onResume() Called after the

OnCreateView()

even with getActivity().getSupportFragmentManager().beginTransaction().remove(this).commit();

So if you have any conde onResume method you should handle it properly

like image 188
user3594530 Avatar answered Oct 16 '22 21:10

user3594530