Clear back stack using fragments

Question

I ported my Android app to honeycomb and I did a big refactor in order to use fragments  In my previous version  when I pressed the Home button I used to do a ACTIVITY CLEAR TOP in order to reset the back stack    Now my app is just a single Activity with multiple fragments  so when I press the Home button I just replace one of the fragments inside it  How can I clear my back stack without having to use startActivity with the ACTIVITY CLEAR TOP flag

User · Answer

Reading the documentation and studying what the fragment id is, it appears to simply be the stack index, so this works:

fragmentManager.popBackStackImmediate(0, FragmentManager.POP_BACK_STACK_INCLUSIVE);

Zero (0) is the the bottom of the stack, so popping up to it inclusive clears the stack.

CAVEAT: Although the above works in my program, I hesitate a bit because the FragmentManager documentation never actually states that the id is the stack index. It makes sense that it would be, and all my debug logs bare out that it is, but perhaps in some special circumstance it would not? Can any one confirm this one way or the other? If it is, then the above is the best solution. If not, this is the alternative:

while(fragmentManager.getBackStackEntryCount() > 0) { fragmentManager.popBackStackImmediate(); }

User · Answer

To make an answer for  Warpzit s comment and make it easier for others to find   Use   fragmentManager popBackStack null  FragmentManager POP BACK STACK INCLUSIVE

User · Answer

Accepted answer was not enough for me  I had to use     FragmentManager fm   getSupportFragmentManager    int count   fm getBackStackEntryCount    for int i   0  i  lt  count    i        fm popBackStackImmediate

User · Answer

Hi I found a solution which is much better from  https   gist github com ikew0ng 8297033             Remove all entries from the backStack of this fragmentManager         param fragmentManager the fragmentManager to clear      private void clearBackStack FragmentManager fragmentManager        if  fragmentManager getBackStackEntryCount    gt  0            FragmentManager BackStackEntry entry   fragmentManager getBackStackEntryAt 0           fragmentManager popBackStack entry getId    FragmentManager POP BACK STACK INCLUSIVE

User · Answer

It is working for me try this one   public void clearFragmentBackStack             FragmentManager fm   getSupportFragmentManager            for  int i   0  i  lt  fm getBackStackEntryCount   - 1  i                  fm popBackStack

User · Answer

Works for me and easy way without using loop    FragmentManager fragmentManager   getSupportFragmentManager       this will clear the back stack and displays no animation on the screen  fragmentManager popBackStackImmediate null  FragmentManager POP BACK STACK INCLUSIVE

User · Answer

Clear backstack without loops  String name   getSupportFragmentManager   getBackStackEntryAt 0  getName    getSupportFragmentManager   popBackStack name  FragmentManager POP BACK STACK INCLUSIVE     Where name is the addToBackStack   parameter  getSupportFragmentManager   beginTransaction                     replace R id container  fragments get titleCode                    addToBackStack name

User · Answer

I got this working this way   public void showHome         getHandler   post new Runnable              Override         public void run                 final FragmentManager fm   getSupportFragmentManager                while  fm getBackStackEntryCount    gt  0                    fm popBackStackImmediate

User · Answer

private boolean removeFragFromBackStack         try           FragmentManager manager   getSupportFragmentManager            List lt Fragment gt  fragsList   manager getFragments            if  fragsList size      0                return true                    manager popBackStack null  FragmentManager POP BACK STACK INCLUSIVE           return true        catch  Exception e            e printStackTrace              return false

User · Answer

I just wanted to add  --  Popping out from backstack using following     fragmentManager popBackStack     is just about removing the fragments from the transaction  no way it is going to remove the fragment from the screen  So ideally  it may not be visible to you but  there may be two or three fragments stacked over each other  and on back key press the UI may look cluttered stacked   Just taking a simple example -  Suppose you have a fragmentA which  loads Fragmnet B using fragmentmanager replace   and then we do addToBackStack  to save this transaction  So the flow is  --  STEP 1 -     FragmentA- FragmentB  we moved to FragmentB  but Fragment A is in background  not visible    Now You do some work in fragmentB and press the Save button   which after saving should go back to fragmentA   STEP 2-  On save of FragmentB  we go back to FragmentA   STEP 3 - So common mistake would be    in Fragment B we will do fragment Manager replace   fragmentB with fragmentA   But  what actually is happenening  we are loading Fragment A again  replacing FragmentB   So now there are two FragmentA  one from STEP-1  and one from this STEP-3     Two instances of FragmentsA are stacked over each other  which may  not be visible   but it is there   So even if we do clear the backstack by above methods  the transaction is cleared but not the actual fragments  So ideally in such a particular case  on press of save button you simply need to go back to fragmentA by simply doing fm popBackStack   or fm popBackImmediate     So correct Step3-  fm popBackStack    go back to  fragmentA  which is already in memory

User · Answer

With all due respect to all involved parties  I m very surprised to see how many of you could clear the entire fragment back stack with a simple  fm popBackStack null  FragmentManager POP BACK STACK INCLUSIVE    According to Android documentation  regarding the name argument - the  null  in the claimed working proposals       If null  only the top state is popped   Now  I do realize that I m lacking knowledge of your particular implementations  like how many entries you have in the back stack at the given point in time   but I would bet all my money on the accepted answer when expecting a well defined behaviour over a wider range of devices and vendors    for reference  something along with this   FragmentManager fm   getFragmentManager       or  getSupportFragmentManager     int count   fm getBackStackEntryCount    for int i   0  i  lt  count    i            fm popBackStack

User · Answer

Just use this method and pass Context  amp  Fragment tag upto which we need to remove the backstake fragments    Usage  clearFragmentByTag context  FragmentName class getName        public static void clearFragmentByTag Context context  String tag        try           FragmentManager fm     AppCompatActivity  context  getSupportFragmentManager             for  int i   fm getBackStackEntryCount   - 1  i  gt   0  i--                String backEntry   fm getBackStackEntryAt i  getName                if  backEntry equals tag                     break                else                    fm popBackStack                                  catch  Exception e            System out print       Popbackstack error       e           e printStackTrace

User · Answer

private void clearBackStack            SupportFragmentManaer fm   getSupportFragmentManager            fm popBackStack null  FragmentManager POP BACK STACK INCLUSIVE           Call to this method would be very neat    No Loop required  If you are using animation in fragments  it will not show too many animations  But using loop will

User · Answer

I posted something similar here  From Joachim s answer  from Dianne Hackborn   http   groups google com group android-developers browse thread thread d2a5c203dad6ec42  I ended up just using   FragmentManager fm   getActivity   getSupportFragmentManager    for int i   0  i  lt  fm getBackStackEntryCount      i            fm popBackStack        But could equally have used something like     AppCompatActivity getContext    getSupportFragmentManager   popBackStack String name  FragmentManager POP BACK STACK INCLUSIVE    Which will pop all states up to the named one  You can then just replace the fragment with what you want

[android] Clear back stack using fragments

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