Fragment onResume() & onPause() is not called on backstack

Question

I have multiple fragment inside an activity. On a button click I am starting a new fragment, adding it to backstack. I naturally expected the onPause() method of current Fragment and onResume() of new Fragment to be called. Well it is not happening.

LoginFragment.java

public class LoginFragment extends Fragment{
  @Override
  public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
      final View view  =   inflater.inflate(R.layout.login_fragment, container, false);
      final FragmentManager mFragmentmanager =  getFragmentManager();

      Button btnHome  = (Button)view.findViewById(R.id.home_btn);
      btnHome.setOnClickListener(new View.OnClickListener() {
        public void onClick(View view){
           HomeFragment fragment    = new HomeFragment();
           FragmentTransaction ft2   =  mFragmentmanager.beginTransaction();
           ft2.setCustomAnimations(R.anim.slide_right, R.anim.slide_out_left
                    , R.anim.slide_left, R.anim.slide_out_right);
           ft2.replace(R.id.middle_fragment, fragment);
           ft2.addToBackStack(""); 
           ft2.commit();    
         }
      });
  }

  @Override
  public void onResume() {
     Log.e("DEBUG", "onResume of LoginFragment");
     super.onResume();
  }

  @Override
  public void onPause() {
    Log.e("DEBUG", "OnPause of loginFragment");
    super.onPause();
  }
}

HomeFragment.java

public class HomeFragment extends Fragment{
  @Override
  public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
     final View view  =   inflater.inflate(R.layout.login_fragment, container, false);
  }

  @Override
  public void onResume() {
     Log.e("DEBUG", "onResume of HomeFragment");
     super.onResume();
  }

  @Override
  public void onPause() {
     Log.e("DEBUG", "OnPause of HomeFragment");
     super.onPause();
  }
}

What I expected, was,

When button is clicked, LoginFragment gets replaced with HomeFragment, onPause() of LoginFragment, and onResume() of HomeFragment gets called
When back is pressed, HomeFragment is poped out and LoginFragment is seen, and onPause() of HomeFragment and onResume() of LoginFragment gets called.

What I am getting is,

When button is clicked, HomeFragment is correctly replacing LoginFragment, onResume() of HomeFragment is called, but onPause() of LoginFragment is never called.
When back pressed, HomeFragment is correctly popping to reveal LoginFragment, onPause() of HomeFragment gets called, but onResume() of LoginFragment never gets called.

Is this the normal behaviour? Why is onResume() of LoginFragment not getting called when I press the back button.

i'm having the sample problem, on pause not get called, how did you resolve this, — Sam, Sep 15 '12 at 17:42
I had the same problem but realised i was using ft2.add(); instead of ft2.replace(). Only other reason would be if your activity is keeping a reference to the fragment (adding it to a collection, or assigning it to a class variable) — Friggles, Feb 25 '13 at 21:13
I am having the same problem. I noticed that .replace() will call the necessary lifecycle methods, but it essentially destroys the fragment. Also, onSaveInstanceState is *not* called. As such, I cannot keep its state. So, I need to use add, but the onResume/Pause is not called :( — ariets, Apr 04 '13 at 17:01
FWIW, my experience is that support library fragments do call onPause and onResume when pushing/popping backstack, but the Android built-in fragments do not. Haven't found a proper workaround for that yet. — benkc, Dec 22 '14 at 19:18
why do you inflate login_fragment in the home fragment? is that a typing mistake? — Maverick Meerkat, Nov 20 '18 at 09:35
@DavidRefaeli Ya it was a typo. I tried to clean up the code base (removing some un important contents) before posting here. I no longer has access to this code (This question was asked 6 years ago). But I remember I got this working that day. — Krishnabhadra, Nov 20 '18 at 11:20

score 206 · Accepted Answer · edited May 22 '14 at 10:06

206

The fragments onResume() or onPause() will be called only when the Activities onResume() or onPause() is called. They are tightly coupled to the Activity.

Read the Handling the Fragment Lifecycle section of this article.

edited May 22 '14 at 10:06

Stephen Ostermiller

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answered Apr 27 '13 at 13:55

Sagar Waghmare

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In the article, it is said that "once the activity reaches the resumed state, you can freely add and remove fragments to the activity. Thus, only while the activity is in the resumed state can the lifecycle of a fragment change independently." Does this mean that the fragment onResume can be called even if the activity onResume is not called ? – thd May 27 '14 at 08:55
3

as for native (not support) fragments in 4.4 (not sure if it's true for older versions) onPause() and onResume() are called not only when these events occur in the activity, but for example when you call replace() or add()/remove() while performing transaction, so this answer is misleading at least for the recent versions of Android. – Dmide Nov 25 '14 at 14:37
33

According to that document, the fragment should actually be moved to the stopped state when swapped out into the backstack. But not only are onPause and onResume not getting called, neither are onStop and onStart -- or for that matter, any other lifecycle methods. So the guide is definitely misleading. – benkc Dec 22 '14 at 19:20
3

Although not related but I found this question while searching for my problem of `onPause()` getting called after `onSaveInstanceState()` instead of before it. This can be reproduced if you to a different child in my `FragmentStatePagerAdapter` (say you move from child 0 to child 2, **note to self, this happens because child 0 is destroyed when child 2 opens**) – Sufian Aug 28 '15 at 14:17
Not sure what you mean. Calling ft.replace should trigger the onPause (of the replaced fragment) and onResume (of the replacing fragment). This is done regardless of any activity... – Maverick Meerkat Nov 20 '18 at 09:40
I can confirm that this effect does not exist in the latest Android 9.0. The fragment::onResume() get invoked when popped up from the backstack. I can also confirm that we had this issue before, about 3/4 years ago. – Qylin Mar 07 '19 at 16:29

score 23 · Answer 2 · edited Apr 27 '13 at 14:10

23

Since you have used ft2.replace(), FragmentTransaction.remove() method is called and the Loginfragment will be removed. Refer to this. So onStop() of LoginFragment will be called instead of onPause(). (As the new fragment completely replaces the old one).
But since you have also used ft2.addtobackstack(), the state of the Loginfragment will be saved as a bundle and when you click back button from HomeFragment, onViewStateRestored() will be called followed by onStart() of LoginFragment. So eventually onResume() won't be called.

edited Apr 27 '13 at 14:10

Robert

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answered Apr 27 '13 at 13:45

Gopal

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`onViewStateRestored` is called if you have `setRetainInstance(true)` – Farid Feb 29 '20 at 07:40
and `setRetainInstance` is currently deprecated in favor of the viewModel pattern :/ – Izadi Egizabal Jul 19 '21 at 00:50

score 18 · Answer 3 · answered Nov 24 '16 at 17:41

Here's my more robust version of Gor's answer (using fragments.size()is unreliable due to size not being decremented after fragment is popped)

getFragmentManager().addOnBackStackChangedListener(new FragmentManager.OnBackStackChangedListener() {
        @Override
        public void onBackStackChanged() {
            if (getFragmentManager() != null) {

                Fragment topFrag = NavigationHelper.getCurrentTopFragment(getFragmentManager());

                if (topFrag != null) {
                    if (topFrag instanceof YourFragment) {
                        //This fragment is being shown. 
                    } else {
                        //Navigating away from this fragment. 
                    }
                }
            }
        }
    });

And the 'getCurrentTopFragment' method:

public static Fragment getCurrentTopFragment(FragmentManager fm) {
    int stackCount = fm.getBackStackEntryCount();

    if (stackCount > 0) {
        FragmentManager.BackStackEntry backEntry = fm.getBackStackEntryAt(stackCount-1);
        return  fm.findFragmentByTag(backEntry.getName());
    } else {
        List<Fragment> fragments = fm.getFragments();
        if (fragments != null && fragments.size()>0) {
            for (Fragment f: fragments) {
                if (f != null && !f.isHidden()) {
                    return f;
                }
            }
        }
    }
    return null;
}

score 13 · Answer 4 · edited Dec 11 '15 at 23:46

13

If you really want to replace fragment inside other fragment you should use Nested Fragments.

In your code you should replace

final FragmentManager mFragmentmanager =  getFragmentManager();

with

final FragmentManager mFragmentmanager =  getChildFragmentManager();

edited Dec 11 '15 at 23:46

Josh Crozier

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answered Apr 24 '13 at 15:55

Bersh

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score 8 · Answer 5 · answered Oct 13 '16 at 13:47

getFragmentManager().addOnBackStackChangedListener(new FragmentManager.OnBackStackChangedListener() {
        @Override
        public void onBackStackChanged() {
            List<Fragment> fragments = getFragmentManager().getFragments();
            if (fragments.size() > 0 && fragments.get(fragments.size() - 1) instanceof YoureFragment){
                //todo if fragment visible
            } else {
                //todo if fragment invisible
            }

        }
    });

but be careful if more than one fragment visible

Thanks, it works, but if only one fragment is visible (so, `ViewPager` with fragments will reference to its fragments). — CoolMind, Aug 02 '18 at 10:36

score 4 · Answer 6 · answered May 19 '17 at 20:45

I have a code very similar to yours and if it works onPause () and onResume (). When changing the fragment, these functions are activated respectively.

Code in fragment:

 @Override
public void onResume() {
    super.onResume();
    sensorManager.registerListener(this, proximidad, SensorManager.SENSOR_DELAY_NORMAL);
    sensorManager.registerListener(this, brillo, SensorManager.SENSOR_DELAY_NORMAL);
    Log.e("Frontales","resume");
}

@Override
public void onPause() {
    super.onPause();
    sensorManager.unregisterListener(this);
    Log.e("Frontales","Pause");

}

Log when change of fragment:

05-19 22:28:54.284 2371-2371/madi.cajaherramientas E/Frontales: resume
05-19 22:28:57.002 2371-2371/madi.cajaherramientas E/Frontales: Pause
05-19 22:28:58.697 2371-2371/madi.cajaherramientas E/Frontales: resume
05-19 22:29:00.840 2371-2371/madi.cajaherramientas E/Frontales: Pause
05-19 22:29:02.248 2371-2371/madi.cajaherramientas E/Frontales: resume
05-19 22:29:03.718 2371-2371/madi.cajaherramientas E/Frontales: Pause

Fragment onCreateView:

View rootView;
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {

    rootView = inflater.inflate(R.layout.activity_proximidad, container, false);
    ButterKnife.bind(this,rootView);
    inflar();
    setTextos();
    return rootView;
}

Action when I pulse back (in the activity where I load the fragment):

@Override
public void onBackPressed() {

    int count = getFragmentManager().getBackStackEntryCount();

    if (count == 0) {
        super.onBackPressed();

    } else {
        getFragmentManager().popBackStack();
    }

 }

Depends on how you are "changing" your fragment. If you `add` it and then popBack then `onResume` won't be called. Probably you're `replacing` fragments and on popBack you get `onResume` callback fired — Farid, Mar 10 '21 at 05:41

score 4 · Answer 7 · answered May 10 '19 at 22:20

I use in my activity - KOTLIN

supportFragmentManager.addOnBackStackChangedListener {
                val f = supportFragmentManager.findFragmentById(R.id.fragment_container)

                if (f?.tag == "MyFragment")
                {
                    //doSomething
                }
            }

score 3 · Answer 8 · answered Dec 10 '17 at 09:01

3

What i do in child fragment:

@Override
public void onDetach() {
   super.onDetach();
   ParentFragment pf = (ParentFragment) this.getParentFragment();
   pf.onResume();
}

And then override onResume on ParentFragment

answered Dec 10 '17 at 09:01

Guillermo De Juan

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You should never call lifecycle methods manually, especially inside each other – breakline Jan 31 '18 at 10:24
@breakline this technique works. Do you have any other way? – Viks Mar 06 '18 at 08:07
Yes, you should add your own implementation to call because lifecycle methods are also called by the system and if you call lifecycle methods inside each other like this you might (and most likely will) cause later issues. – breakline Mar 06 '18 at 12:14

score 1 · Answer 9 · edited May 23 '17 at 12:26

If you add the fragment in XML, you can't swap them dynamically. What happens is they overly, so they events don't fire as one would expect. The issue is documented in this question. FragmenManager replace makes overlay

Turn middle_fragment into a FrameLayout, and load it like below and your events will fire.

getFragmentManager().beginTransation().
    add(R.id.middle_fragment, new MiddleFragment()).commit();

score 1 · Answer 10 · answered Jan 20 '16 at 12:25

You can try this,

Step1: Override the Tabselected method in your activity

@Override
public void onTabSelected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
    // When the given tab is selected, switch to the corresponding page in
    // the ViewPager.
    try {
    if(MyEventsFragment!=null && tab.getPosition()==3)
    {
        MyEvents.fragmentChanged();
    }
    }
    catch (Exception e)
    {

    }
    mViewPager.setCurrentItem(tab.getPosition());
}

Step 2: Using static method do what you want in your fragment,

public static void fragmentChanged()
{
    Toast.makeText(actvity, "Fragment Changed", Toast.LENGTH_SHORT).show();
}

score 1 · Answer 11 · edited Apr 02 '17 at 19:29

1

onPause() method works in activity class you can use:

public void onDestroyView(){
super.onDestroyView    
}

for same purpose..

edited Apr 02 '17 at 19:29

Mohammad Tayyab

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answered Apr 02 '17 at 13:44

Vikrant Kaloniya

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CoolMind · Answer 12 · 2018-08-02T12:39:38.977

Based on the answer of @Gor I wrote similar in Kotlin. Place this code in onCreate() of an activity. It works for one fragment visible. If you have ViewPager with fragments, it will call ViewPager's fragment, not a previous one.

supportFragmentManager.addOnBackStackChangedListener {
    supportFragmentManager.fragments.lastOrNull()?.onResume()
}

After reading https://medium.com/@elye.project/puzzle-fragment-stack-pop-cause-issue-on-toolbar-8b947c5c07c6 I understood that it would be better in many situations to attach new fragments with replace, not add. So a need in onResume in some cases will disappear.

score 1 · Answer 13 · answered Jun 01 '21 at 14:39

for me, the cause was using navGraph to switch between fragments

app:navGraph

create the fragment like this (in Kotlin) and then all the lifecycle functions get called

val transaction = supportFragmentManager.beginTransaction()
transaction.replace(R.id.nav_host_fragment, fragment)
transaction.addToBackStack(null)
transaction.commit()

score 0 · Answer 14 · edited Oct 11 '13 at 16:38

0

You simple can't add a fragment to a fragment. This needs to happen in the FragmentActivity. I assume you are creating the LoginFragment in a FragmentActivity, so in order to get this working you need to add the HomeFragment via the FragmentActivity when the login closes.

The general point is that you need a FragmentActivity class from where you add each Fragment to the FragmentManager. It is not possible to do this inside a Fragment class.

edited Oct 11 '13 at 16:38

spaaarky21

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answered Nov 07 '12 at 20:53

Nickolaus

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Yes they are inside a fragment activity. – Krishnabhadra Nov 08 '12 at 02:11
if fragments are added dynamically then you can add as many fragment as you want to a fragment but not to the ones defined in xml tag – Illegal Argument Jun 12 '14 at 10:51
Nested fragments are now fully supported by AndroidX. – aberaud May 21 '21 at 18:13

score 0 · Answer 15 · edited Jul 16 '14 at 11:29

0

A fragment must always be embedded in an activity and the fragment's lifecycle is directly affected by the host activity's lifecycle. For example, when the activity is paused, so are all fragments in it, and when the activity is destroyed, so are all fragments

edited Jul 16 '14 at 11:29

Krishnabhadra

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answered Jul 16 '14 at 11:23

Zar E Ahmer

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score 0 · Answer 16 · answered Apr 09 '18 at 21:09

0

Follow the below steps, and you shall get the needed answer

1- For both fragments, create a new abstract parent one.
2- Add a custom abstract method that should be implemented by both of them.
3- Call it from the current instance before replacing with the second one.

answered Apr 09 '18 at 21:09

Mostafa Magdy

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How does it help in situation when a user returns from fragment 2 to fragment 1? – CoolMind Jul 20 '18 at 12:31

score 0 · Answer 17 · answered Nov 20 '18 at 09:44

0

Calling ft.replace should trigger the onPause (of the replaced fragment) and onResume (of the replacing fragment).

I do notice that your code inflates login_fragment on the home fragment, and also doesn't return the views in the onCreateView. If these are typos, can you show how these fragments are being called from within your activity?

answered Nov 20 '18 at 09:44

Maverick Meerkat

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This is not an answered, what if "add" is must for someone's design?! – Farid Mar 08 '19 at 12:22

score 0 · Answer 18 · answered Oct 26 '21 at 02:10

There are two possible override methods guaranteed to be called when a fragment appears/disappears.

oncreateview/ondestroyview - this is called whenever the fragment visibility changes

onpause/onresume - called when the app is closed by external or you use fragment replace

If you wish to create a hook as I did so you can by notified whenever a fragment is closed and catch either situation without creating a duplicate call as sometimes both could be called.

try extending the fragment class and add a boolean flag in both overrides so you catch the open and close for sure without duplicating

score 0 · Answer 19 · answered Oct 12 '22 at 00:47

kotlin

requireFragmentManager().addOnBackStackChangedListener {
            val fragments: List<Fragment> = requireFragmentManager().fragments
            if (fragments.isNotEmpty() && fragments[fragments.size - 1] is YOUR_FRAGMENT) {
                //todo if fragment visible
            } else {
                //todo if fragment invisible
            }
        }

score -3 · Answer 20 · edited Mar 07 '13 at 13:26

While creating a fragment transaction, make sure to add the following code.

// 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);

Also make sure, to commit the transaction after adding it to backstack

Fragment onResume() & onPause() is not called on backstack

LoginFragment.java

HomeFragment.java

20 Answers20

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