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

User · Answer

onPause   method works in activity class you can use   public void onDestroyView    super onDestroyView         for same purpose

User · Answer

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

User · Answer

Although with different code  I experienced the same problem as the OP  because I originally used   fm beginTransaction                add R id fragment container main  fragment               addToBackStack null               commit      instead of  fm beginTransaction                    replace R id fragment container main  fragment                   addToBackStack null                   commit      With  replace  the first fragment gets recreated when you return from the second fragment and therefore onResume   is also called

User · Answer

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

User · Answer

I use in my activity - KOTLIN  supportFragmentManager addOnBackStackChangedListener                   val f   supportFragmentManager findFragmentById R id fragment container                   if  f  tag     MyFragment                                           doSomething

User · Answer

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  amp  amp  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

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

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  gt  0            FragmentManager BackStackEntry backEntry   fm getBackStackEntryAt stackCount-1           return  fm findFragmentByTag backEntry getName           else           List lt Fragment gt  fragments   fm getFragments            if  fragments    null  amp  amp  fragments size   gt 0                for  Fragment f  fragments                    if  f    null  amp  amp   f isHidden                          return f                                                      return null

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

getFragmentManager   addOnBackStackChangedListener new FragmentManager OnBackStackChangedListener              Override         public void onBackStackChanged                 List lt Fragment gt  fragments   getFragmentManager   getFragments                if  fragments size    gt  0  amp  amp  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

User · Answer

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

[android] Fragment onResume() & onPause() is not called on backstack

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